The researchers found sugars like arabinose and xylose -- but the most significant finding was ribose.
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D-xylose reductase (, XylR, XyrA, msXR, dsXR, monospecific xylose reductase, dual specific xylose reductase, NAD(P)H-dependent xylose reductase, xylose reductase) is an enzyme with systematic name xylitol:NAD(P)+ oxidoreductase. This enzyme catalyses the following chemical reaction : xylitol + NAD(P)+ \rightleftharpoons D-xylose + NAD(P)H + H+ Xylose reductase catalyses the initial reaction in the xylose utilization pathway, the NAD(P)H dependent reduction of xylose to xylitol.
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The systematic name of this enzyme class is D-xylose aldose-ketose- isomerase. Other names in common use include D-xylose isomerase, D-xylose ketoisomerase, and D-xylose ketol-isomerase.
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In enzymology, an UTP—xylose-1-phosphate uridylyltransferase () is an enzyme that catalyzes the chemical reaction :UTP + alpha-D-xylose 1-phosphate \rightleftharpoons diphosphate + UDP-xylose Thus, the two substrates of this enzyme are UTP and alpha-D-xylose 1-phosphate, whereas its two products are diphosphate and UDP-xylose. This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing nucleotide groups (nucleotidyltransferases). The systematic name of this enzyme class is UTP:alpha-D-xylose-1-phosphate uridylyltransferase. Other names in common use include xylose-1-phosphate uridylyltransferase, uridylyltransferase, xylose 1-phosphate, UDP-xylose pyrophosphorylase, uridine diphosphoxylose pyrophosphorylase, and xylose 1-phosphate uridylyltransferase.
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In this pathway the enzyme xylose isomerase converts D-xylose directly into D-xylulose. D-xylulose is then phosphorylated to D-xylulose-5-phosphate as in the oxido-reductase pathway. At equilibrium, the isomerase reaction results in a mixture of 83% D-xylose and 17% D-xylulose because the conversion of xylose to xylulose is energetically unfavorable.
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However, it does not natively metabolize xylose. This limits the usefulness of S. cerevisiae in the production of fuels and chemicals from plant cell walls, which contain a large amount of xylose. In response, S. cerevisiae has been engineered to ferment xylose through the addition of the S. stiptis genes, XYL1 and XYL2, coding for xylose reductase and xylitol dehydrogenase, respectively. The concerted action of these enzymes converts xylose to xylulose, which is naturally fermented by S. cerevisae.
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Arabinoxylan chains contain a large number of 1,4-linked xylose units. Many xylose units are substituted with 2, 3 or 2,3-linked arabinose residues.
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In enzymology, a D-xylose 1-dehydrogenase () is an enzyme that catalyzes the chemical reaction :D-xylose + NAD+ \rightleftharpoons D-xylonolactone + NADH + H+ Thus, the two substrates of this enzyme are D-xylose and NAD+, whereas its 3 products are D-xylonolactone, NADH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is D-xylose:NAD+ 1-oxidoreductase. Other names in common use include NAD+-D-xylose dehydrogenase, D-xylose dehydrogenase, and (NAD+)-linked D-xylose dehydrogenase. This enzyme participates in pentose and glucuronate interconversions.
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Xylose isomerase that can be isolated from red Chinese rice wine, which contains the bacterium Lactobacillus xylosus. This bacterium was mistakenly classified as a L. plantarum, which normally grows on the sugar L-arabinose, and rarely grown on D-xylose. L. xylosus was recognized to be distinct for its ability to grow on D-xylose. Xylose isomerase in L. xylosus has a molecular weight of about 183000 Daltons.
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In enzymology, a D-xylose 1-dehydrogenase (NADP+) () is an enzyme that catalyzes the chemical reaction :D-xylose + NADP+ \rightleftharpoons D-xylono-1,5-lactone + NADPH + H+ Thus, the two substrates of this enzyme are D-xylose and NADP+, whereas its 3 products are D-xylono-1,5-lactone, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is D-xylose:NADP+ 1-oxidoreductase. Other names in common use include D-xylose (nicotinamide adenine dinucleotide phosphate), dehydrogenase, D-xylose-NADP+ dehydrogenase, D-xylose:NADP+ oxidoreductase, and D-xylose 1-dehydrogenase (NADP+).
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This pathway is also called the “Xylose Reductase-Xylitol Dehydrogenase” or XR-XDH pathway. Xylose reductase (XR) and xylitol dehydrogenase (XDH) are the first two enzymes in this pathway. XR reduces D-xylose to xylitol using NADH or NADPH. Xylitol is then oxidized to D-xylulose by XDH, using the cofactor NAD.
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Xylose is a hemicellulosic sugar found in all angiosperm plants. As such xylose constitutes the second most abundant carbohydrate moiety in nature. Xylose can be produced from wood or agricultural residues through auto- or acid hydrolysis. Ethanol production from such lignocellulosic residues does not compete with food production through the consumption of grain.
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In enzymology, a L-xylose 1-dehydrogenase () is an enzyme that catalyzes the chemical reaction :L-xylose + NADP+ \rightleftharpoons L-xylono-1,4-lactone + NADPH + H+ Thus, the two substrates of this enzyme are L-xylose and NADP+, whereas its 3 products are L-xylono-1,4-lactone, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH- OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-xylose:NADP+ 1-oxidoreductase. Other names in common use include L-xylose dehydrogenase, and NADPH-xylose reductase.
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Xylose isomerase acts to convert fructose sugars into glucose. Dietary supplements of xylose isomerase may improve some symptoms of fructose malabsorption, although there is currently only a single scientific study available.
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D-xylose absorption test is a medical test performed to diagnose conditions that present with malabsorption of the proximal small intestine due to defects in the integrity of the gastrointestinal mucosa.D-xylose absorption MedlinePlus. Accessed 19 Dec 2012. D-xylose is a monosaccharide, or simple sugar, that does not require enzymes for digestion prior to absorption.
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Xylose is metabolised by humans, although it is not a major human nutrient and is largely excreted by the kidneys. Humans can obtain xylose only from their diet. An oxidoreductase pathway is present in eukaryotic microorganisms. Humans have enzymes called protein xylosyltransferases (XYLT1, XYLT2) which transfer xylose from UDP to a serine in the core protein of proteoglycans.
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Additional modifications are necessary for rapid fermentation of xylose, however.
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Reduction of xylose by catalytic hydrogenation produces the sugar substitute xylitol.
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In attempts to generate S. cerevisiae strains that are able to ferment D-xylose the XYL1 and XYL2 genes of P. stipitis coding for the D-xylose reductase (XR) and xylitol dehydrogenase (XDH), respectively were introduced in S. cerevisiae by means of genetic engineering. XR catalyze the formation of xylitol from D-xylose and XDH the formation of D-xylulose from xylitol. Saccharomyces cerevisiae can naturally ferment D-xylulose through the pentose phosphate pathway. In another approach, bacterial xylose isomerases have been introduced into S. cerevisiae.
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It is desirable to ferment D-xylose to ethanol. This can be accomplished either by native xylose fermenting yeasts such as Scheffersomyces Pichia stipitis or by metabolically engineered strains of Saccharomyces cerevisiae. Pichia stipitis is not as ethanol tolerant as the traditional ethanol producing yeast Saccharomyces cerevisiae. S. cerevisiae on the other hand can not ferment D-xylose to ethanol.
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In enzymology, an UDP-arabinose 4-epimerase () is an enzyme that catalyzes the chemical reaction :UDP-L-arabinose \rightleftharpoons UDP-D-xylose Hence, this enzyme has one substrate, UDP-L-arabinose, and one product, UDP-D-xylose. This enzyme belongs to the family of isomerases, specifically those racemases and epimerases acting on carbohydrates and derivatives. The systematic name of this enzyme class is UDP-L-arabinose 4-epimerase. Other names in common use include uridine diphosphoarabinose epimerase, UDP arabinose epimerase, uridine 5'-diphosphate-D-xylose 4-epimerase, and UDP-D-xylose 4-epimerase.
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In enzymology, a xylose isomerase () is an enzyme that catalyzes the interconversion of D-xylose and D-xylulose. This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases interconverting aldoses and ketoses. The isomerase has now been observed in nearly a hundred species of bacteria. Xylose-isomerases are also commonly called fructose-isomerases due to their ability to interconvert glucose and fructose.
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B. breve strains can ferment mannitol and sorbitol, but not arabinose or xylose.
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Xylose D-Xylose is a five-carbon aldose (pentose, monosaccharide) that can be catabolized or metabolized into useful products by a variety of organisms. There are at least four different pathways for the catabolism of D-xylose: An oxido-reductase pathway is present in eukaryotic microorganisms. Prokaryotes typically use an isomerase pathway, and two oxidative pathways, called Weimberg and Dahms pathways respectively, are also present in prokaryotic microorganisms.
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Xylobiose is a disaccharide of xylose monomers with a beta-1,4-bond between them.
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The aim of this genetic recombination in the laboratory is to develop a yeast strain that efficiently produces ethanol. However, the effectiveness of D-xylose metabolizing laboratory strains do not always reflect their metabolism abilities on raw xylose products in nature. Since D-xylose is mostly isolated from agricultural residues such as wood stocks then the native or genetically altered yeasts will need to be effective at metabolizing these less pure natural sources. Varying expression of the XR and XDH enzyme levels have been tested in the laboratory in the attempt to optimize the efficiency of the D-xylose metabolism pathway.
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A decreased urinary excretion of D-xylose is seen in conditions involving the gastrointestinal mucosa, such as small intestinal bacterial overgrowth and Whipple's disease. In cases of bacterial overgrowth, the values of D-xylose absorption return to normal after treatment with antibiotics. In contrast, if the D-xylose urinary excretion is not normal after a course of antibiotics, then the problem must be due to a non- infectious cause of malabsorption (i.e., celiac disease).
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Xylose contains 2.4 calories per gram (lower than glucose or sucrose, approx. 4 calories per gram).
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Xyloglucan has a backbone of β1→4-linked glucose residues, most of which are substituted with 1-6 linked xylose sidechains. The xylose residues are often capped with a galactose residue sometimes followed by a fucose residue. The specific structure of xyloglucan differs between plant families.
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UDP-glucuronic acid decarboxylase 1 is an enzyme that in humans is encoded by the UXS1 gene. UDP-glucuronate decarboxylase (UGD; EC 4.1.1.35) catalyzes the formation of UDP-xylose from UDP-glucuronate. UDP-xylose is then used to initiate glycosaminoglycan biosynthesis on the core protein of proteoglycans.
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Most pentoses and some hexoses are all substrates for D-xylose isomerase. Some examples include: D-ribose, L-arabinose, L-rhanmose, and D-allose. Conversion of glucose to fructose by xylose isomerase was first patented in the 1960s, however, the process was not industrially viable as the enzymes were suspended in solution, and recycling the enzyme was problematic. An immobile xylose isomerase that was fixed on a solid surface was first developed in Japan by Takanashi.
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Alpha-D-xyloside xylohydrolase (, alpha-xylosidase) is an enzyme. This enzyme catalyses the following chemical reaction : Hydrolysis of terminal, non- reducing alpha-D-xylose residues with release of alpha-D-xylose. The enzyme catalyses hydrolysis of a terminal, unsubstituted xyloside at the extreme reducing end of a xylogluco-oligosaccharide.
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A xyloside is a type of glycoside derived from the sugar xylose. Proteoglycan (PG) synthesis is initiated by the transfer of D-xylose from UDP-xylose to a serine residue in core proteins. This natural primer acts as a template for the assembly of heparin sulfate, heparin, chondroitin sulfate, and dermatan sulfate side chains, depending on the tissue. However, in 1973 it was determined that synthetic B-D-xylosides can prime glycosaminoglycan (GAG) synthesis by substituting for the core xylosylated protein.
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The reaction is used in carbohydrate chemistry as a chain extension method for example that of D-xylose.
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The protein encoded by this gene is an isoform of xylosyltransferase, which belongs to a family of glycosyltransferases. This enzyme transfers xylose from UDP-xylose to specific serine residues of the core protein and initiates the biosynthesis of glycosaminoglycan chains in proteoglycans including chondroitin sulfate, heparan sulfate, heparin and dermatan sulfate.
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Xylose (cf. , xylon, "wood") is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group. It is derived from hemicellulose, one of the main constituents of biomass.
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UDP-xylose and UDP-N-acetylglucosamine transporter is a protein that in humans is encoded by the SLC35B4 gene.
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Xylosyltransferase 1 is an enzyme that in humans is encoded by the XYLT1 gene. Xylosyltransferase (XT; EC 2.4.2.26) catalyzes the transfer of UDP-xylose to serine residues within XT recognition sequences of target proteins. Addition of this xylose to the core protein is required for the biosynthesis of the glycosaminoglycan chains characteristic of proteoglycans.
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In enzymology, an UDP-glucuronate decarboxylase () is an enzyme that catalyzes the chemical reaction :UDP-D-glucuronate \rightleftharpoons UDP-D-xylose + CO2 Hence, this enzyme has one substrate, UDP-D-glucuronate, and two products, UDP-D-xylose and CO2. This enzyme belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is UDP-D-glucuronate carboxy-lyase (UDP- D-xylose-forming). Other names in common use include uridine- diphosphoglucuronate decarboxylase, and UDP-D-glucuronate carboxy-lyase.
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The activity of D-xylose isomerase was first observed by Mitsuhashi and Lampen in 1953 in the bacterium Lactobacillus pentosus. Artificial production through transformed E.coli have also been successful. In 1957, the D-xylose isomerase activity on D-glucose conversion to D-fructose was noted by Kooi and Marshall. It is now known that isomerases have broad substrate specificity.
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Molecular structure of an hypothetical xylooligosaccharide, where n is a variable number of xylose units. Xylooligosaccharides (XOS) are polymers of the sugar xylose. They are produced from the xylan fraction in plant fiber. Their C5 (where C is a quantity of carbon atoms in each monomer) structure is fundamentally different from other prebiotics, which are based upon C6 sugars.
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The xylan polymers can be hydrolyzed into xylose, which is catalytically hydrogenated into xylitol. The conversion changes the sugar (xylose, an aldehyde) into the primary alcohol, xylitol. Impurities are then removed. The processing is often done using standard industrial methods; industrial fermentation involving bacteria, fungi, or yeast, especially Candida tropicalis, are common, but are not as efficient.
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A computational method, IPRO, recently predicted mutations that experimentally switched the cofactor specificity of Candida boidinii xylose reductase from NADPH to NADH.
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Acid hydrolysis of hemicelluloses during sulfite pulping produces monosaccharides, predominantly mannose for softwoods and xylose for hardwoods, which can be fermented to produce ethanol.
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Xylanase catalyzes the catabolism of xylan into xylose. Given that plants contain a lot of xylan, xylanase is thus important to the nutrient cycle.
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The Weimberg pathway is an oxidative pathway where the D-xylose is oxidized to D-xylono-lactone by a D-xylose dehydrogenase followed by a lactonase to hydrolyze the lactone to D-xylonic acid. A xylonate dehydratase is splitting off a water molecule resulting in 2-keto 3-deoxy- xylonate. A second dehydratase forms the 2-keto glutarate semialdehyde which is subsequently oxidised to 2-ketoglutarate.
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3-O-alpha-D-mannopyranosyl-alpha-D-mannopyranose xylosylphosphotransferase (, XPT1) is an enzyme with systematic name UDP-D-xylose:3-O-alpha-D- mannopyranosyl-alpha-D-mannopyranose xylosylphosphotransferase. This enzyme catalyses the following chemical reaction : UDP-xylose + 3-O-alpha-D- mannopyranosyl-alpha-D-mannopyranose \rightleftharpoons UMP + 3-O-(6-O-alpha- D-xylosylphospho-alpha-D-mannopyranosyl)-alpha-D-mannopyranose Mn2+ required for activity.
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On June 3, 2015, Mascoma LLC and the U.S. U.S. Department of Energy's BioEnergy Science Center announced development of a new strain of yeast developed by Mascoma and BESC for cellulosic ethanol production. The product, named C5 FUEL, is a yeast capable of converting xylose into ethanol. Xylose is a sugar found in cellulosic biomass that can not be fermented by conventional ethanol-fermenting yeast.
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Oligosaccharide reducing-end xylanase (, Rex, reducing end xylose-releasing exo-oligoxylanase) is an enzyme with systematic name beta-D- xylopyranosyl-(1->4)-beta-D-xylopyranose reducing-end xylanase. This enzyme catalyses the following chemical reaction : Hydrolysis of (1->4)-beta-D-xylose residues from the reducing end of oligosaccharides The enzyme acts rapidly on the beta-anomer of beta-D-xylopyranosyl-(1->4)-beta-D-xylopyranose.
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By far the most common use of isomerases in industrial applications is in sugar manufacturing. Glucose isomerase (also known as xylose isomerase) catalyzes the conversion of D-xylose and D-glucose to D-xylulose and D-fructose. Like most sugar isomerases, glucose isomerase catalyzes the interconversion of aldoses and ketoses. The conversion of glucose to fructose is a key component of high-fructose corn syrup production.
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The main advantage to hot water extraction is that it offers a method where the only chemical that is needed is water, making this environmentally friendly and cheap. The hot water treatment goal is achieve as much removal of hemilleculose from the wood as possible. This is done through the hydrolysis of the hemicellulose to achieve smaller oligomers and monosacccharie xylose. Xylose when dehydrated becomes furfural.
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Several scientists have determined the composition of plant root mucilage using monosaccharide analysis and linkage analysis, showing that Maize (Zea mays) root mucilage contains high levels of galactose, xylose, arabinose, rhamnose, and glucose, and lower levels of uronic acid, mannose, fucose, and glucuronic acid. Wheat (Triticum aestivum) root mucilage also contains high levels of xylose, arabinose, galactose, glucose, and lower levels of rhamnose, glucuronic acid and mannose. Cowpea (Vigna unguiculata) also contains high levels of arabinose, galactose, glucose, fucose, and xylose, and lower levels of rhamnose, mannose, and glucuronic acid. Many other plants have had their root mucilage composition determined using monosaccharide analysis and monosaccharide linkage analysis.
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Recent computational redesign by Costas Maranas and coworkers was also capable of experimentally switching the cofactor specificity of Candida boidinii xylose reductase from NADPH to NADH.
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Fructan - A polysaccharide of fructose 3\. Galactan - A polysaccharide of galactose 4\. Araban - A polysaccharide of arabinose 5\. Xylan - A polysaccharide of xylose Champe, Harvey, Ferrier.
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Anoxybacillus gonensis is a moderately thermophilic, xylose-utilizing, endospore-forming bacterium. It is Gram-positive and rod-shaped, with type strain G2T (=NCIMB 13933T =NCCB 100040T).
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The bark is known to be rich in tannins, saponins, alkaloids, lipids, phytosterols, glucosides, xylose, rhamnose, arabinose, lupeol, methoxychalcones, and kukulkanins. Additionally, Mimosa hostilis contains labdane diterpenoids.
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This enzyme participates in pentose and glucuronate interconversions and fructose and mannose metabolism. The most bio-available sugars according to the International Society of Rare Sugars are: glucose, galactose, mannose, fructose, xylose, ribose, and L-arabinose. Twenty hexoses and nine pentoses, including xylulose, were considered to be "rare sugars". Hence D-xylose isomerase is used to produce these rare sugars which have very important applications in biology despite their low abundance.
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In enzymology, a xylitol oxidase () is an enzyme that catalyzes the chemical reaction :xylitol + O2 \rightleftharpoons xylose + H2O2 Thus, the two substrates of this enzyme are xylitol and O2, whereas its two products are xylose and H2O2. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with oxygen as acceptor. The systematic name of this enzyme class is xylitol:oxygen oxidoreductase.
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Growth was not observed on single sugars or amino acids such as D-glucose, D-galactose, D-fructose, D-xylose, lactose, maltose, sucrose, alanine, glutamate, glycine, and histidine.
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Xylonic acid is a sugar acid that can be obtained by oxidation of the hemiacetal/aldehyde group of xylose. The C-2 epimer is known as lyxonic acid.
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HS synthesis initiates with the transfer of xylose from UDP- xylose by xylosyltransferase (XT) to specific serine residues within the protein core. Attachment of two galactose (Gal) residues by galactosyltransferases I and II (GalTI and GalTII) and glucuronic acid (GlcA) by glucuronosyltransferase I (GlcATI) completes the formation of a core protein linkage tetrasaccharide βGlcA-1,3-βGal-1,3-βGal-1,4-βXyl. Xylose attachment to the core protein is thought to occur in the endoplasmic reticulum (ER) with further assembly of the linkage region and the remainder of the chain occurring in the golgi apparatus. The pathways for HS/heparin or chondroitin sulfate (CS) and dermatan sulfate (DS) biosynthesis diverge after the formation of this common linkage structure.
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Xylan is made from units of the pentose sugar xylose, which is known for being the first saccharide in multiple biosynthetic pathways of anionic polysaccharides such as heparan sulfate and chondroitin sulfate. Like Xylan, heparan sulfate it is found on the cell surface; since it is needed for both the cell surface and extracellular matrix,it may explain CXorf26's high expression in nearly all human tissues. Heparan biosynthesis occurs in the lumen of the endoplasmic reticulum and is initiated by the transfer of a xylose from UDP-xylose by xylosyltransferase to specific serine residues within the protein core. PSORTII predicts the presence of a KKXX-like motif, GEKA, near the C-terminus of CXorf26.
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In enzymology, a 1,4-beta-D-xylan synthase () is an enzyme that catalyzes the chemical reaction :UDP-D-xylose + (1,4-beta-D-xylan)n \rightleftharpoons UDP + (1,4-beta-D-xylan)n1 Thus, the two substrates of this enzyme are UDP-D-xylose and (1,4-beta-D-xylan)n, whereas its two products are UDP and (1,4-beta-D- xylan)n+1. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D-xylose:1,4-beta-D-xylan 4-beta-D-xylosyltransferase. Other names in common use include uridine diphosphoxylose-1,4-beta-xylan xylosyltransferase, 1,4-beta-xylan synthase, xylan synthase, and xylan synthetase.
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Products containing Xylose-Isomerase are sold as over- the-counter dietary supplements to combat fructose malabsorption, primarily in Europe and under brand names including Fructaid, Fructease and Fructosin. Apart from general concerns over the effectiveness of OTC-enzymes, there is currently very limited research available on Xylose-Isomerase as a dietary supplement, with the sole scientific study indicating a positive effect on malabsorption-related nausea and abdominal pain, but none on bloating.
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Absence of proteoglycans is associated with heart and respiratory failure, defects in skeletal development and increased tumor metastasis. Different types of proteoglycans exist, depending on the sugar that is linked to the oxygen atom of the residue in the protein. For example, the GAG heparan sulphate is attached to a protein serine residue through a xylose sugar. The structure is extended with several N-acetyllactosamine repeating sugar units added onto the xylose.
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Xethanol says it plans to increase production and profitability with new technology it has under development. Xylose Technologies, Inc. (XTI), a subsidiary of Xethanol, is conducting collaborative research through a Cooperative Research and Development Agreement (CRADA) with the USDA Forest Service, Forest Products Laboratory (FPL) located on the campus of the University of Wisconsin–Madison. The work focuses on genetically engineering proprietary yeast strains for the efficient production of xylitol from xylose.
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Arabinoxylan is a hemicellulose found in both the primary and secondary cell walls of plants, including woods and cereal grains, consisting of copolymers of two pentose sugars: arabinose and xylose.
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In 2014 a low-temperature , atmospheric-pressure enzyme-driven process to convert xylose into hydrogen with nearly 100% of the theoretical yield was announced. The process employs 13 enzymes, including xylulokinase.
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Modifications to this flux that may improve ethanol production include deleting the GND1 gene, or the ZWF1 gene. Since the pentose phosphate pathway produces additional NADPH during metabolism, limiting this step will help to correct the already evident imbalance between NAD(P)H and NAD+ cofactors and reduce xylitol byproduct formation. Another experiment comparing the two D-xylose metabolizing pathways revealed that the XI pathway was best able to metabolize D-xylose to produce the greatest ethanol yield, while the XR-XDH pathway reached a much faster rate of ethanol production. Overexpression of the four genes encoding non-oxidative pentose phosphate pathway enzymes Transaldolase, Transketolase, Ribulose-5-phosphate epimerase and Ribose-5-phosphate ketol-isomerase led to both higher D-xylulose and D-xylose fermentation rate.
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Xylose is the main building block for the hemicellulose xylan, which comprises about 30% of some plants (birch for example), far less in others (spruce and pine have about 9% xylan). Xylose is otherwise pervasive, being found in the embryos of most edible plants. It was first isolated from wood by Finnish scientist, Koch, in 1881,Advances in carbohydrate chemistry, Volume 5, pg 278 Hudson & Cantor 1950 but first became commercially viable, with a price close to sucrose, in 1930.Pentose Metabolism 1932 Xylose is also the first saccharide added to the serine or threonine in the proteoglycan type O-glycosylation, and, so, it is the first saccharide in biosynthetic pathways of most anionic polysaccharides such as heparan sulfate and chondroitin sulfate.
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Xylose, fucose, mannose, and GlcNAc phosphoserine glycans have been reported in the literature. Fucose and GlcNAc have been found only in Dictyostelium discoideum, mannose in Leishmania mexicana, and xylose in Trypanosoma cruzi. Mannose has recently been reported in a vertebrate, the mouse, Mus musculus, on the cell-surface laminin receptor alpha dystroglycan4. It has been suggested this rare finding may be linked to the fact that alpha dystroglycan is highly conserved from lower vertebrates to mammals.
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Hemicellulose contains xylan, which itself is composed of xylose in β(1,4) linkages. The use of glucose isomerase very efficiently converts xylose to xylulose, which can then be acted upon by fermenting yeast. Overall, extensive research in genetic engineering has been invested into optimizing glucose isomerase and facilitating its recovery from industrial applications for re- use. Glucose isomerase is able to catalyze the isomerization of a range of other sugars, including D-ribose, D-allose and L-arabinose.
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In enzymology, a dolichyl-phosphate D-xylosyltransferase () is an enzyme that catalyzes the chemical reaction :UDP-D-xylose + dolichyl phosphate \rightleftharpoons UDP + dolichyl D-xylosyl phosphate Thus, the two substrates of this enzyme are UDP-D-xylose and dolichyl phosphate, whereas its two products are UDP and dolichyl D-xylosyl phosphate. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D-xylose:dolichyl-phosphate D-xylosyltransferase.
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N. sinuspersici sp. nov has been observed to utilize carbon sources including d-Galactose , lactose, melibiose, glycerol, sucrose, maltose, mannitol, d-mannose, l-rhamnose, d-xylose, inulin, citrate, malonate, pyruvate, and propionate.
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Clostridium tyrobutyricum is a rod-shaped, Gram-positive bacterium that grows under anaerobic conditions and produces butyric acid, acetic acid and hydrogen gas as the major fermentation products from glucose and xylose.
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Arabinoxylans are found in both the primary and secondary cell walls of plants and are the copolymers of two sugars: arabinose and xylose. They may also have beneficial effects on human health.
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Sporobolomyces species produce ballistoconidia that are bilaterally symmetrical, they have Coenzyme Q10 or Coenzyme Q10(H2) as their major ubiquinone, they lack xylose in whole-cell hydrolysates, and they cannot ferment sugars.
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The acyclic form of xylose has chemical formula HOCH2(CH(OH))3CHO. The cyclic hemiacetal isomers are more prevalent in solution and are of two types: the pyranoses, which feature six-membered C5O rings, and the furanoses, which feature five-membered C4O rings (with a pendant CH2OH group). Each of these rings is subject to further isomerism, depending on the relative orientation of the anomeric hydroxy group. The dextrorotary form, -xylose, is the one that usually occurs endogenously in living things.
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Xylan backbone synthesis, unlike that of the other hemicelluloses, is not mediated by any cellulose synthase-like proteins. Instead, xylan synthase is responsible for backbone synthesis, facilitating the addition of xylose. Several genes for xylan synthases have been identified. Several other enzymes are utilized for the addition and modification of the side-chain units of xylan, including glucuronosyltransferase (which adds glucuronic acid units), xylosyltransferase (which adds additional xylose units), arabinosyltransferase (which adds arabinose), methyltransferase (responsible for methylation), and acetyltransferase (responsible for acetylation).
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Xylosan (1,4-anhydro-α-D-xylopyranose) is a molecule produced during pyrolysis of the hemicellulose found in wood. Xylosan is the dehydrated product of the 5-carbon xylose sugar monomer, a major component of hemicellulose.
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Fungal growth can be supported by D-glucose, D-mannose, D-xylose, L-sorbose, D-fructose, D-galactose, sucrose, D-mannitol, SorbitolD-sorbital, ethanol and glycerol. Sporulation often requires a balance of carbon and nitrogen.
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In 2014 a low-temperature , atmospheric-pressure enzyme-driven process to convert xylose into hydrogen with nearly 100% of the theoretical yield was announced. The process employs 13 enzymes, including a novel polyphosphate xylulokinase (XK).
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O. valericigenes grows fermentatively, producing predominantly valerate when grown on a glucose carbon source. The bacteria were observed to grow in culture using D-glucose, L-arabinose, D-ribose, and D-xylose as carbon sources.
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Recently, engineered yeasts have been described efficiently fermenting xylose, and arabinose, and even both together.Karhumaa K, Wiedemann B, Hahn-Hagerdal B, Boles E, Gorwa-Grauslund MF (2006) Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains. Microb Cell Fact. 10;5:18. Yeast cells are especially attractive for cellulosic ethanol processes because they have been used in biotechnology for hundreds of years, are tolerant to high ethanol and inhibitor concentrations and can grow at low pH values to reduce bacterial contamination.
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Ever since then, core α1,3-fucose emerged as the structural element most relevant as a CCD in plants and insect allergens. Much later, both xylose and core α1,3-fucose were revealed as heart pieces of two independent glycan epitopes for rabbit IgG. The occurrence of human anti-xylose IgE, however, has not been verified so far. Still, because of the two possible epitopes and the different carrier structures, the plural CCDs is in frequent use even though core α1,3-fucose appears to be the single culprit.
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In South Africa certain species of Protea (in particular Protea humiflora, P. amplexicaulis, P. subulifolia, P. decurrens and P. cordata) are adapted to pollination by rodents (particularly Cape Spiny Mouse, Acomys subspinosus) and elephant shrews (Elephantulus species). The flowers are borne near the ground, are yeasty smelling, not colourful, and sunbirds reject the nectar with its high xylose content. The mice apparently can digest the xylose and they eat large quantities of the pollen. In Australia pollination by flying, gliding and earthbound mammals has been demonstrated.
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30 wt. %), whereas tender stem tips exhibit a low cellulose content (9.2 wt. %). Salicornia brachiata revealed the dominance of rhamnose, arabinose, mannose, galactose, and glucose, with meager presence of ribose and xylose in their structural polysaccharide.
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Xylose isomerase has a structure that is based on eight alpha/beta barrels that create an active site holding two divalent magnesium ions. Xylose isomerase enzymes exhibit a TIM barrel fold with the active site in the centre of the barrel and a tetrameric quaternary structure.Deprecated services < EMBL-EBI PDB structures are available in the links in the infobox to the right. The protein is a tetramer where paired barrels are nearly coaxial, which form two cavities in which the divalent metals are both bound to one of the two cavities.
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Principal structure of glucuronoxylan in hardwood Glucuronoxylans are the primary components of hemicellulose as found in hardwood trees, for example birch. They are hemicellulosic plant cell wall polysaccharides, containing glucuronic acid and xylose as its main constituents. They are linear polymers of β-D-xylopyranosyl units linked by (1→4) glycosidic bonds, with many of the xylose units substituted with 2, 3 or 2,3-linked glucuronate residue, which are often methylated at position 4. Most of the glucuronoxylans have single 4-O-methyl-α-D-glucopyranosyl uronate residues (MeGlcA) attached at position 2.
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The hemicellulose is a polymer of mainly five-carbon sugars C5H10O5 (xylose).Xylose, Material Measurement Technology, National Institute of Standards and Technology (NIST), (2011) and the cellulose is a polymer of six- carbon sugar C6H12O6 (glucose).Glucose, Material Measurement Technology, National Institute of Standards and Technology (NIST), (2011) Cellulose fibers are considered to be a plant’s structural building blocks and are tightly bound to lignin, but the biomass can be deconstructed using Acid hydrolysis, enzymatic hydrolysis, organosolv dissolution, autohydrolysis or supercritical hydrolysis. Biomass (cellulose, hemicellulose and lignocellulose) contain vast amounts of fermentable sugars.
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In enzymology, a zeatin O-beta-D-xylosyltransferase () is an enzyme that catalyzes the chemical reaction :UDP-D-xylose + zeatin \rightleftharpoons UDP + O-beta-D-xylosylzeatin Thus, the two substrates of this enzyme are UDP-D- xylose and zeatin, whereas its two products are UDP and O-beta-D- xylosylzeatin. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D-xylose:zeatin O-beta-D-xylosyltransferase. Other names in common use include uridine diphosphoxylose-zeatin xylosyltransferase, and zeatin O-xylosyltransferase.
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For instance, besides glucose, sugar monomers in hemicelluloses can include the five-carbon sugars xylose and arabinose, the six-carbon sugars mannose and galactose, and the six-carbon deoxy sugar rhamnose. Hemicelluloses contain most of the D-pentose sugars, and occasionally small amounts of L-sugars as well. Xylose is in most cases the sugar monomer present in the largest amount, although in softwoods mannose can be the most abundant sugar. Not only regular sugars can be found in hemicellulose, but also their acidified form, for instance glucuronic acid and galacturonic acid can be present.
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Many Beta-D- xylosides have been studied for use as xylose primes with varying results.Esko and Montgomery 1995 # Priming requires the Beta-anomer of xylose.Galligani et al. 1975 # Priming activity correlates with the activity of the aglycone (cite).
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It is used in biochemistry, since it has 20-26% content of protein, 32-36% of which are crude proteins. The plant also contains glucose (10–16%), rhamnose (36–40%), uronic acids (27–29%), and xylose (10–13%).
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P. rettgeri can be identified by its motility and its ability to produce acid from mannitol. It does not produce gas from glucose and does not ferment lactose. It also does not produce hydrogen sulfide or acid from xylose.
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Streptomyces olivochromogenes is a bacterium species from the genus of Streptomyces which has been isolated from soil.Deutsche Sammlung von Mikroorganismen und Zellkulturen Streptomyces olivochromogenes produces ferulic acid. The xylose isomerase from Streptomyces olivochromogenes is used in the food industry.
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The linker is composed of four saccharides, first one being xylose, which is an unusual sugar in a unique place, attached to serine of the protein core and sequentially followed by two galactose and a β-D-glucuronic acid [1, 12].
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Xylose, an abundant five carbon sugar found predominantly in hemicellulose of angiosperms, can be converted to xylitol through biochemical or chemical reduction. The USDA and other university research labs have hundreds of such CRADAs with many companies exploring the technology.
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In J. Lodder (ed.), The Yeasts. A taxonomic study, 2nd ed. North-Holland Publishing Co., Amsterdam The genus is monotypic, containing the single species Pachysolen tannophilus, the first yeast identified to have a high capacity for production of ethanol from xylose.
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The first metal, mentioned earlier, coordinates to O3 and O4, and is used to dock the substrate. ring opening mechanism of glucose In the isomerization of xylose, crystal data has shown that xylose sugar binds to the enzyme in an open chain conformation. Metal 1 binds to O2 and O4, and once bound, metal 2 binds to O1 and O2 in the transition state, and these interactions along with a lysine residue help catalyze the hydride shift necessary for isomerization. The transition state consists of a high energy carbonium ion that is stabilized through all the metal interactions with the sugar substrate.
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Given the abundance of xylose and its potential for the bioconversion of lignocellulosic materials to renewable fuels, Pichia stipitis has been extensively studied. The complete sequencing of its genome was announced in 2007. Native strains of S. stipitis have been shown to produce ≈50 g/l ethanol in 48 h from pure xylose in defined minimal medium using urea as a nitrogen source. S. stipitis is a predominantly haploid yeast but strains can be induced to mate with themselves or with other strains of S. stipitis by cultivating cells on minimal medium containing limiting amounts of carbon sources and nitrogen.
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In a trials of nitrogen utilization, T. polystichi was able to use ammonium chloride, ammonium citrate, ammonium nitrate, ammonium sulfate, magnesium nitrate, potassium nitrate, sodium nitrate, dl-alpha alanine, l-arginine, dl-aspartic acid, l-glutamic acid, dl-histidine, and dl-valine. In trials of carbon utilization, T. polystichi was able to use dextrose, sucrose, maltose, melezitose, trehalose, dextrin, inulin, and mannitol. It was unable to use lactose, rhamnose, inositol, i-erythritol, xylose, and succinic acid. The ability to use mannitol and the inability to use xylose and succinic acid distinguished it from the other species tested.
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In enzymology, a flavonol-3-O-glycoside xylosyltransferase () is an enzyme that catalyzes the chemical reaction :UDP-D-xylose + a flavonol 3-O-glycoside \rightleftharpoons UDP + a flavonol 3-[-D-xylosyl-(1->2)-beta-D-glycoside] Thus, the two substrates of this enzyme are UDP-D-xylose and flavonol 3-O-glycoside, whereas its two products are UDP and flavonol 3-[-D-xylosyl-(1->2)-beta-D-glycoside]. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D-xylose:flavonol-3-O-glycoside 2-O-beta-D- xylosyltransferase.
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Glycoside hydrolases are typically named after the substrate that they act upon. Thus glucosidases catalyze the hydrolysis of glucosides and xylanases catalyze the cleavage of the xylose based homopolymer xylan. Other examples include lactase, amylase, chitinase, sucrase, maltase, neuraminidase, invertase, hyaluronidase and lysozyme.
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The aldo-keto reductase family is a family of proteins that are subdivided into 16 categories; these include a number of related monomeric NADPH- dependent oxidoreductases, such as aldehyde reductase, aldose reductase, prostaglandin F synthase, xylose reductase, rho crystallin, and many others.
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The most efficient substrates are those similar to glucose and xylose, having equatorial hydroxyl groups at the third and fourth carbons. The current model for the mechanism of glucose isomerase is that of a hydride shift based on X-ray crystallography and isotope exchange studies.
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From many of the rhamnose residues, sidechains of various neutral sugars branch off. The neutral sugars are mainly D-galactose, L-arabinose and D-xylose, with the types and proportions of neutral sugars varying with the origin of pectin.RG-I. Ccrc.uga.edu. Retrieved 2012-07-16.
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In the last step D-xylulose is phosphorylated by an ATP utilising kinase, XK, to result in D-xylulose-5-phosphate which is an intermediate of the pentose phosphate pathway. Because of the varying cofactors needed in this pathway and the degree to which they are available for usage, a cofactor imbalance can result in an accumulation of the intermediate xylitol when there is insufficient regeneration of NAD. This typically occurs under oxygen limiting conditions or when non-native xylose fermenting yeasts are engineered with the oxido-reductase pathway. It is less common in native xylose fermenting yeasts that have biochemical mechanisms for regenerating NAD under oxygen limitation.
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Traditionally, baker's yeast (Saccharomyces cerevisiae), has long been used in the brewery industry to produce ethanol from hexoses (six- carbon sugars). Due to the complex nature of the carbohydrates present in lignocellulosic biomass, a significant amount of xylose and arabinose (five- carbon sugars derived from the hemicellulose portion of the lignocellulose) is also present in the hydrolysate. For example, in the hydrolysate of corn stover, approximately 30% of the total fermentable sugars is xylose. As a result, the ability of the fermenting microorganisms to use the whole range of sugars available from the hydrolysate is vital to increase the economic competitiveness of cellulosic ethanol and potentially biobased proteins.
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An extensive genetic toolbox has been developed for S. stipitis that includes synthetic drug resistance markers for nourseothricin acetyltransferase gene (nat1), hygromycin (hph) and a synthetic form of Cre that enables excision of the markers. Engineered strains of S. stipitis will produce 57 g/l ethanol from pure xylose in under 48 h and adapted strains will produce significant amounts of ethanol from acid hydrolysates of lignocellulose. This natural ability of S. stipitis to ferment xylose to ethanol, has inspired efforts to engineer this trait into Saccharomyces cerevisiae. S. cerevisiae is preferred for ethanol production from grain and sugar cane, because it ferments hexose sugars very rapidly and is very robust.
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In enzymology, a xylosylprotein 4-beta-galactosyltransferase () is an enzyme that catalyzes the chemical reaction :UDP-galactose + O-beta-D-xylosylprotein \rightleftharpoons UDP + 4-beta-D-galactosyl-O-beta-D-xylosylprotein Thus, the two substrates of this enzyme are UDP-galactose and O-beta-D-xylosylprotein, whereas its two products are UDP and 4-beta-D-galactosyl-O-beta-D- xylosylprotein. This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-galactose:O-beta-D-xylosylprotein 4-beta-D-galactosyltransferase. Other names in common use include UDP-D-galactose:D-xylose galactosyltransferase, UDP-D-galactose:xylose galactosyltransferase, galactosyltransferase I, and uridine diphosphogalactose-xylose galactosyltransferase.
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In enzymology, a protein xylosyltransferase () is an enzyme that catalyzes the chemical reaction in which a beta-D-xylosyl residue is transferred from UDP-D- xylose to the sidechain oxygen atom of a serine residue in a protein. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D- xylose:protein beta-D-xylosyltransferase. Other names in common use include UDP-D-xylose:core protein beta-D-xylosyltransferase, UDP-D-xylose:core protein xylosyltransferase, UDP-D-xylose:proteoglycan core protein beta-D- xylosyltransferase, UDP-xylose-core protein beta-D-xylosyltransferase, uridine diphosphoxylose-core protein beta-xylosyltransferase, and uridine diphosphoxylose-protein xylosyltransferase.
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Lyxose is an aldopentose -- a monosaccharide containing five carbon atoms, and including an aldehyde functional group. It has chemical formula 5105. It is a C'-2 carbon epimer of the sugar xylose. Lyxose occurs only rarely in nature, for example, as a component of bacterial glycolipids.
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T. elfii has flagella uniformly distributed around its body, making it a peritrichous bacteria. It is also an obligate anaerobe, meaning it cannot tolerate oxygen. Electron acceptors include thiosulfate, arabinose, bio-trypticase, fructose, glucose, lactose, maltose, ribose, sucrose, and xylose. Electron donors include acetate, carbon dioxide, and hydrogen.
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Under reduced oxygen tension, optimum growth was observed on pectin, raffinose, rhamnose, sucrose, xylose, maltose, melibiose and galactose.whereas carboxylic acids and most alcohols were not utilised. Anaerobic growth occurred by means of fermenting sugars and polysaccharides. The product of cellulose degradation under anoxic conditions are acetate and hydrogen.
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2006, 281, 1426-1431 Substrates of glycosynthase include Glucose, Galactose, Mannose, Xylose, and Glucuronic acid.Wilkinson, S.; Liew, C.; Mackay, J.; Salleh, H.; Withers, S.; McLeod, M. Org Lett. 2008, 10, 1585-1588. Modern methods to prepare glycosynthase use directed evolution to introduce modifications, which improve the enzymes function.
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Sakamoto, T.; Hasunuma, T.; Hori, Y.; Yamada, R.; Kondo, A. Direct ethanol production from hemicellulosic materials of rice straw by use of an engineered yeast strain codisplaying three types of hemicellulolytic enzymes on the surface of xylose-utilizing Saccharomyces cerevisiae cells. J. Biotechnol. 2012, 158, 203-210. Sakamoto (2012) et al.
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To dissolve some soluble substances such as xylose, bamboo must be saturated for months in a river or pond, spoiling the starch so it does not attract moths or parasites. Wood that must be buried underground is first burnt to make the ground harder and to give it a layer of protection.
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A. xylosoxidans is a Gram-negative rod that does not form spores. It is motile, with peritrichous flagella that distinguish it from Pseudomonas species, and is oxidase-positive, catalase-positive, and citrate-positive. It is urease and indole-negative. It produces acid oxidatively from xylose, but not from lactose, maltose, mannitol, or sucrose.
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Saccharomyces yeasts have been genetically engineered to ferment xylose, one of the major fermentable sugars present in cellulosic biomasses, such as agriculture residues, paper wastes, and wood chips. Such a development means ethanol can be efficiently produced from more inexpensive feedstocks, making cellulosic ethanol fuel a more competitively priced alternative to gasoline fuels.
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Under aerobic conditions, for example, D-glucose is used, but no acid is formed, as would be typical for fermentation. Other usable substrates are glycerol, L-arabinose, D-xylose, D-galactose, D-glucose, D-fructose, D-mannose, L-rhamnose, D-mannitol, N-acetylglucosamine, arbutin, aesculin, salicin, D-cellobiose, D-maltose, D-melibiose, sucrose, D-trehalose, D-raffinose, starch, glycogen, D-turanose, potassium gluconate and potassium 5-ketogluconate. Furthermore amino acids leucine and valine are assimilated. Carbohydrates that cannot be used are erythritol, D-arabinose, D-ribose, L-xylose, D-ribitol, methyl-β-D-xylopyranoside, L-sorbose, dulcitol, inositol, D-sorbitol, Methly-α-D-mannopyranoside, methly-α-D-glucopyranoside, amygdalin, D-lactose, inulin, D-melezitose, xylitol, gentiobiose, D-lyxose, D-tagatose, fucose, arabitol and potassium 2-ketogluconate.
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Zingibain exhibits complex-type N-linked oligosaccharide chains at two residues. Chains are between 5-13 glycosyl units long, and composed of N-acetylglucosamine, fucose, mannose, and xylose. Zingibain sugar sequences are almost identical to oligosaccharides seen in lectins from Japanese pagoda tree seeds, laccase a from sycamore cells, and S-glycoproteins from Brassica campestris.
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These developments were essential to the development of industrial fermentation processes used in manufacturing high fructose corn syrup. The tertiary structure was determined for several xylose isomerases from microbes starting in the mid 1980s (Streptomyces olivochromogenes in 1988, Streptomyces violaceoniger in 1988, Streptomyces rubiginosus in 1984, Arthrobacter B3728 in 1986, Actinoplanes missouriensis in 1992, and Clostridium thermosulfurogenes in 1990).
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2019.1681660 The roots of the plant have been shown to contain up to 10% tannin. A substance similar to adrenaline has been found within the plant's leaves. Mimosa pudica's seeds produce mucilage made up of D-glucuronic acid and D-xylose. Additionally, extracts of M. pudica have been shown to contain crocetin-dimethylester, tubulin, and green-yellow fatty oils.
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Hemicelluloses are polysaccharides related to cellulose that comprise about 20% of the biomass of land plants. In contrast to cellulose, hemicelluloses are derived from several sugars in addition to glucose, especially xylose but also including mannose, galactose, rhamnose, and arabinose. Hemicelluloses consist of shorter chains – between 500 and 3000 sugar units. Furthermore, hemicelluloses are branched, whereas cellulose is unbranched.
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Apiose- and the Xylose-substituted variants of above molecule. QS-21 is a purified plant extract used as a vaccine adjuvant. It is derived from the soap bark tree (Quillaja saponaria), which is native to the country of Chile. The extract contains water-soluble triterpene glycosides, which are members of a family of plant-based compounds called saponins.
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A diploid isolate of C. blankii had an observed "potential for use in single cell protein production from hemicellulose hydrolysates", which is related to Cellulosic ethanol (i.e., ethanol production). This yeast is one of several studied extensively for use in xylose fermentation. C. blankii has been tested as an aid for the degradation of hemicellulose hydrolycates.
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Dictyoglomus is a genus of bacterium, given its own subphylum, called the Dictyoglomi. This organism is extremely thermophilic, meaning it thrives at extremely high temperatures. It is chemoorganotrophic, meaning it derives energy by metabolizing organic molecules. This organism is of interest because it elaborates an enzyme, xylanase, which digests xylan, a heteropolymer of the pentose sugar xylose.
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The isomerization of xylose to xylulose has its own commercial applications as interest in biofuels has increased. This reaction is often seen naturally in bacteria that feed on decaying plant matter. Its most common industrial use is in the production of ethanol, achieved by the fermentation of xylulose. The use of hemicellulose as source material is very common.
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Some members of subdivision 1 are able to use D-glucose, D-xylose, and lactose as carbon sources, but are unable to use fucose or sorbose. Members of subdivision 1 also contain enzymes such as galactosidases used in the breakdown of sugars. Members of subdivision 4 have been found to use chitin as a carbon source.
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Sugars are normally fermented by all Blastobotrys species. Interestingly, B. elegans is the only Blastobotrys species discovered, without the ability to ferment sugar in anaerobic conditions. Subsequently, with the absence of respiration, there is no observed B. elegans growth on D-galactose, D-glucose, D-xylose, lactose, maltose, raffinose, starch and trehalose. It is also unable to ferment insulin.
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A. oligospora is considered a saprobe and is more saprotrophic than other nematode capturing fungi. At first the fungus was considered largely saprophytic in nature but this interpretation was later questioned. Saprophytic growth uses D-xylose, D-mannose, and cellobiose. The fungus uses nitrite, nitrate, and ammonium for its nitrogen sources and uses pectin, cellulose, and chitin for its carbon sources.
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Xylogalacturonan beta-1,3-xylosyltransferase (, xylogalacturonan xylosyltransferase, XGA xylosyltransferase) is an enzyme with systematic name UDP-D-xylose:xylogalacturonan 3-beta-D-xylosyltransferase. This enzyme catalyses the following chemical reaction : Transfers a xylosyl residue from UDP-D-xylose to a D-galactose residue in xylogalacturonan, forming a beta-1,3-D-xylosyl-D-galactose linkage. This enzyme is involved in plant cell wall synthesis.
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The structural formula of prymnesin-2 is: C96H136Cl3NO35. The compound has two chiral centers, at the carbon atoms C14 and C85. The molecule is amphoteric, which means that it can act both as base and an acid. This is because all 16 hydroxyls, except for one at C32, are concentrated on carbons C48-84, and there is a xylose moiety at C77.
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The carbohydrate content can be defined as the sum of the amounts of the five principal, neutral wood monosaccharides; arabinose, galactose, glucose, mannose and xylose in anhydrous form, in a sample, in milligrams per gram. In the determination, the samples are hydrolyzed with sulphuric acid using a two- step technique. The amounts of the different monosaccharides are determined using ion chromatography (IC).
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Enzyme changes shape by induced fit upon substrate binding to form enzyme-substrate complex. Hexokinase has a large induced fit motion that closes over the substrates adenosine triphosphate and xylose. Binding sites in blue, substrates in black and Mg2+ cofactor in yellow. (, ) The different mechanisms of substrate binding The classic model for the enzyme-substrate interaction is the induced fit model.
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The GC content of H. turkmenica was determined to be 64% for its draft genome with 49 RNA genes predicted using RAST. The protein coding sequences were also digested using RAST. This revealed 193 subsystems including several enzymes encoding genes for carboxylase, cellulase and xylanase enzymes, xylose isomerase, and carboxylesterase. Other genes coding for biosynthesis of peptides and secondary metabolites were also detected.
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Xylans are polysaccharides made up of β-1,4-linked xylose (a pentose sugar) residues with side branches of α-arabinofuranose and α-glucuronic acids and contribute to cross-linking of cellulose microfibrils and lignin through ferulic acid residues. On the basis of substituted groups xylan can be categorized into three classes i) glucuronoxylan (GX) ii) neutral arabinoxylan (AX) and iii) glucuronoarabinoxylan (GAX).
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When xylose and fufural are the goal, acid catalysts, such as formic acid, are added to increase the transition of polysaccharide to monosaccharide. This catalyst also has been show to also utilize a solvent effect to be aid the reaction. One method of pretreatment is to soak the wood with diluted acids (with concentrations around 4%). This converts the hydroloze hemicellulose into monosaccharaides.
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Rathayibacter toxicus is a chemoorganotroph that utilizes oxygen as its terminal electron acceptor. Using tubes of Medium C containing a variety of carbon sources, each 0.5% weight per volume concentration, noting growth and acid production for 4 weeks, it was determined that R. toxicus utilizes galactose, mannose, and xylose as carbon sources forming acidic byproducts. The production of acids from carbohydrates occurs oxidatively and weakly.
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Finally, glycosythase are specific for the donor sugar but often have loose specificity for the acceptor sugar. This can result in different regioselectivity depending on the acceptor resulting in products with different glycosidic linkages. One example is the Agrobacterium sp. β-glucosythase, which forms a β 1-4 glycoside with Glucose as the acceptor, but forms a β 1-3 glycoside with Xylose as the acceptor.
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It can also produce H2S (gas), which is a unique characteristic for a Gram-positive bacillus. Acid is produced from glucose, fructose, galactose, and lactose, but not from maltose, xylose, and mannitol. Sucrose is fermented by most strains of E. tonsillarum, but not by E. rhusiopathiae. Hydrogen sulfide H2S is produced by 95% of strains of Erysipelothrix species as demonstrated on triple sugar iron (TSI) agar.
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Prymnesin-1 is formed of a large polyether polycyclic core with several conjugate double and triple bonds, chlorine and nitrogen heteroatoms and O-linked sugar moieties including α-D-ribofuranose, α-L-arabinopyranose, and β-D-galactofuranose, unlike the single linked L-xylose of prymnesin-2. There are three forms of prymnesin known, prymnesin 1 and 2, differing in their glycosylation, and prymnesin B1 differing in backbone.
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In 2012 Butalco sold its xylose technology to the French yeast producer Lesaffre, which wanted to become the world market leader for yeast for the production of first-generation cereal- based bioethanol and also active in the second generation sector. Two years later Lesaffre took over Butalco completely and integrated it into the Lesaffre group as an independent unit.Gunter Festel: Spin-offs brauchen klare Bekenntnisse laborjournal.de, 3.
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Treponema socranskii differs from others in the genus due, in part, to its metabolism. T. socranskii is able to ferment compounds that others are not able to do so. The compounds that it can metabolize are arabinose, dextrin, fructose, galactose, glucose, glycogen, maltose, mannose, pectin, raffinose, rhamnose, ribose, starch, sucrose, trehalose, and xylose. The fermentation products are acetic, lactic, and succinic acid, with formic acid as a minor product.
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Glycoside hydrolase family 52 CAZY GH_52 comprises enzymes with only one known activity; beta-xylosidase (). Proteins harboring beta- xylosidase and xylanase activities have been identified in the Gram-positive, facultative thermophilic aerobe Bacillus stearothermophilus 21. This microbe, which functions in xylan degradation, can utilise xylan as a sole source of carbon. The enzyme hydrolyses 1,4-beta-D-xylans, removing successive D-xylose residues from the non-reducing termini.
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There is no known cure, but an appropriate diet and the enzyme xylose isomerase can help. The ingestion of glucose simultaneously with fructose improves fructose absorption and may prevent the development of symptoms. For example, people may tolerate fruits such as grapefruits or bananas, which contain similar amounts of fructose and glucose, but apples are not tolerated because they contain high levels of fructose and lower levels of glucose.
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Glucose, glycerol, mannose, starch, maltose, sucrose, glutamate, alanine, ornithine, fumarate, malate, pyruvate, succinate, and lactate substrates support growth. Growth is not sustained on arabinose, lactose, mannitol, rhamnose, sorbitol, galactose, ribose, xylose, arginine, lysine, aspartate, glycine, acetate, propionate, and citrate. Sensitivity to novobiocin, bacitracin, anisomycin, aphidicolin, and rifampicin have been observed. However, no sensitivity has been shown to ampicillin, penicillin, chloramphenicol, erythromycin, neomycin, nalidixic acid, nystatin, tetracycline, streptomycin, or kanamycin.
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Springer-Verlag, 2014, , p. 214\. (german) In addition to the phosphorylation to glucose-6-phosphate, which is part of the glycolysis, glucose can be oxidized during its degradation to glucono-1,5-lactone. Glucose is used in some bacteria as a building block in the trehalose or the dextran biosynthesis and in animals as a building block of glycogen. Glucose can also be converted from bacterial xylose isomerase to fructose.
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Its absorption requires an intact mucosa only. In contrast, polysaccharides require enzymes, such as amylase, to break them down so that they can eventually be absorbed as monosaccharides. This test was previously in use but has been made redundant by antibody tests. In normal individuals, a 25 g oral dose of D-xylose will be absorbed and excreted in the urine at approximately 4.5 g in 5 hours.
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An increase of approximately 12 ppm or more in hydrogen and/or methane during the breath test could conclude bacterial overgrowth. Recent study indicates "The role of testing for SIBO in individuals with suspected IBS remains unclear." The excess hydrogen or methane is assumed to be typically caused by an overgrowth of otherwise normal intestinal bacteria. Other breath tests that can be taken include: sucrose intolerance, d-xylose and sorbitol.
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It is aerobic and heterotrophic. All strains are oxidase positive and catalase positive. Nitrate is reduced to nitrite. Degradation of elastin, starch and casein is positive. Strains SPS-243T, RQ-10 and RQ-12 utilize D-glucose, D-fructose, D-melibiose, D-cellobiose, sucrose, D-trehalose, D-raffinose, D-xylose, L-arabinose, D-sorbitol, D-mannitol, pyruvate, succinate, L-serine, L-asparagine, L-arginine, L-glutamine and L-proline.
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Both growth and quantity of tabtoxin synthesized were significantly affected by carbon source, nitrogen source and amino acid supplements. Sorbitol, xylose and sucrose proved to be the best carbon sources for tabtoxin production. Specific toxin production was very low using glucose as a single carbohydrate source, although bacterial growth was well supported by glucose. Amount and type of nitrogen sources (NH4Cl or KNO3) affected the growth of pv.
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Xylan 1,4-beta-xylosidase (, xylobiase, beta-xylosidase, exo-1,4-beta- xylosidase, beta-D-xylopyranosidase, exo-1,4-xylosidase, exo-1,4-beta-D- xylosidase, 1,4-beta-D-xylan xylohydrolase) is an enzyme with systematic name 4-beta-D-xylan xylohydrolase. This enzyme catalyses the following chemical reaction : Hydrolysis of (1->4)-beta-D-xylans, to remove successive D-xylose residues from the non-reducing termini This enzyme also hydrolyses xylobiose.
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Later her laboratory performed crystallographic analyses of anti-tumor agents and, amongst others, the structure and conformation of estramustine and acridine. They further tested carcinogens such as polycyclic aromatic hydrocarbons as well as the structure of the enzyme xylose isomerase. In 1972 Glusker and structural biologist Helen M. Berman reported on the crystal structure of a nucleic acid-drug complex as a model for anti-tumor agent and mutagen action.
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Pucciniomycetes develop no basidiocarp, karyogamy occurs in a thick-walled resting spore (teliospore), and meiosis occurs upon germination of teliospore. They have simple septal pores without membrane caps and disc-like spindle pole bodies. Except for a few species, the basidia, when present, are transversally septate. Mannose is the major cell wall carbohydrate, glucose, fucose and rhamnose are the less prevalent neutral sugars and xylose is not present.
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The B3GNT1 gene encodes a β-1,4-glucuronyltransferase, designated B4GAT1, that transfers glucuronic acid towards both α- and β-anomers of xylose. B4GAT1 is the priming enzyme for LARGE, a dual-activity glycosyltransferase that is capable of extending products of B4GAT1. Thus, B4GAT1 is involved in the initiation of the LARGE-dependent repeating disaccharide that is necessary for extracellular matrix protein binding to O-mannosylated α-dystroglycan that is lacking in secondary dystroglycanopathies.
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Studies are intensively conducted to develop economic methods to convert both cellulose and hemicellulose to ethanol. Fermentation of glucose, the main product of cellulose hydrolyzate, to ethanol is an already established and efficient technique. However, conversion of xylose, the pentose sugar of hemicellulose hydrolyzate, is a limiting factor, especially in the presence of glucose. Moreover, it cannot be disregarded as hemicellulose will increase the efficiency and cost-effectiveness of cellulosic ethanol production.
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Xylanase () is any of a class of enzymes that degrade the linear polysaccharide xylan into xylose, thus breaking down hemicellulose, one of the major components of plant cell walls. As such, it plays a major role in micro- organisms thriving on plant sources for the degradation of plant matter into usable nutrients. Xylanases are produced by fungi, bacteria, yeast, marine algae, protozoans, snails, crustaceans, insect, seeds, etc.; mammals do not produce xylanases.
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Saccharophagus degradans (formerly Microbulbifer degradans) is a gram- negative, marine bacterium shown to degrade a number of complex polysaccharides as energy source. S. degradans have also been shown to ferment xylose to ethanol. In recent studies, Saccharophagus degradans from Chesapeake Bay was effectively used to produce cellulosic ethanol. Cellulosic ethanol production by means of bacterial action could be the key cheap production of cellulosic ethanol for global mass market production of bioethanol.
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It was heavily stressed by Criegee that the reaction must be run in anhydrous solvents, as any water present would hydrolyze the lead tetraacetate; however, subsequent publications have reported that if the rate of oxidation is faster than the rate of hydrolysis, the cleavage can be run in wet solvents or even aqueous solutions. For example, glucose, glycerol, mannitol, and xylose can all undergo a Criegee oxidation in aqueous solutions, but sucrose cannot.
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P. raffinosivorans is classified as an obligate anaerobic chemoorganotroph, but its specific electron acceptors and donors have remained elusive. P. raffinosivorans can ferment glucose, cellobiose, maltose, fructose, mannitol, mannose, ribose, sucrose, and arabinose to produce acid. It produces propionic acid, carbon dioxide, and acetic acid as products of its fermentative metabolic pathway. It does not produce acid when fermenting amygdalin, glycogen, erythritol, dulcitol, inositol, inulin, starch, melezitose, melibiose, trehalose, raffinose, and xylose.
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Furfural may be obtained by the acid catalyzed dehydration of 5-carbon sugars (pentoses), particularly xylose. : → + 3 These sugars may be obtained from pentosans obtained from hemicellulose present in lignocellulosic biomass/ Between 3% and 10% of the mass of crop residue feedstocks can be recovered as furfural, depending on the type of feedstock. Furfural and water evaporate together from the reaction mixture, and separate upon condensation. The global production capacity is about 800,000 tons as of 2012.
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O-Mannose sugars attached to serine and threonine residues on α-dystroglycan separate the two domains of the protein. Addition of Ribitol-P, xylose and glucuronic acid forms a long sugar that can stabilise the interaction with the basement membrane. O-mannosylation involves the transfer of a mannose from a dolichol-P-mannose donor molecule onto the serine or threonine residue of a protein. Most other O-glycosylation processes use a sugar nucleotide as a donor molecule.
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Since its discovery as a useful method of oxidation, Fétizon's reagent has been used in the total synthesis of numerous molecules such as (±)-bukittinggine. Fétizon's reagent has also been employed extensively in the study of various sugar chemistry, to achieve selective oxidation of tri and tetra methylated aldoses to aldolactones, oxidation of D-xylose and L-arabinose to D-threose and L-erythrose respectively, and oxidation of L-sorbose to afford L-threose among many others.
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The nectar is, however, fortified with a high sugar content; the sugars include xylose. The downward- pointing shape, the odd yeasty odour, high sugar content and the flowering time in late winter all indicate pollination by rodents. Animals which have now been recorded as visiting the flowers are, besides sunbirds, the rodent species Otomys irroratus, Micaelamys namaquensis, Rhabdomys pumilio and Myomyscus verreauxii. Each of these rodents were found with this plants pollen on their noses or in their scat.
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M. verreauxi is the best at climbing and is thought to be the main pollinator. Rhabdomys pumilio, on the other hand, was sometimes found to be quite destructive of the inflorescences in a laboratory setting. In the field on average 20% of the inflorescences are destroyed within a two month period, and this mouse is thought to be likely responsible. The xylose in the nectar can be metabolised by the intestinal microbiotic flora of the small mouse Micaelamys namaquensis.
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Carbon sources used by A. italicus A. italicus uses inositol, fructose, rhamnose, mannitol, xylose, arabinose, sucrose, and glucose as carbon sources for growth. It differs from many members of its genus such as A. utahensis and A. missouriensis, which do not use inositol; from A phillipinesis and A. armeniacus, which use raffinose; and from A. brasiliensis and A phillipinesis, which usw cellulose. A. italicus is also noted to use natural rubber as a sole carbon source.
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Glycosylated serines are often followed by a glycine and have neighboring acidic residues, but this motif does not always predict glycosylation. Attachment of the GAG chain begins with four monosaccharides in a fixed pattern: Xyl - Gal - Gal - GlcA. Each sugar is attached by a specific enzyme, allowing for multiple levels of control over GAG synthesis. Xylose begins to be attached to proteins in the endoplasmic reticulum, while the rest of the sugars are attached in the Golgi apparatus.
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Ulf Ellervik, 2010 Ulf Ellervik (born 7 December 1969) is a Swedish professor of bioorganic chemistry at Lund University. Ellervik's main research area is carbohydrates, such as eye drops against the viral disease epidemic keratoconjunctivitis and the carbohydrate xylose as the cure for cancer. Ellervik received his undergraduate training at the Faculty of Engineering (LTH) where he started in 1989. He graduated as M.Sc. in Chemical Engineering in 1993 and began research in organic chemistry in 1994.
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Its primary nutrients are the sugars xylose, arabinose, glucose, sucrose, ribitol, xylitol and L-arabinitol. It cannot assimilate maltose or lactose; however, it is able to assimilate urea, asparagine, potassium nitrate and ammonium nitrate. The optimal temperature for growth is and the fungus is generally considered to be mesophilic, although it can grow at higher temperatures (up to ) as well. Asexual reproduction manifests in one of two forms: the Scedosporium type (the most common type) and the Graphium type.
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As it is not commercially profitable to extract these products from fruits and vegetables, they are produced by catalytic hydrogenation of the appropriate reducing sugar. For example, xylose is converted to xylitol, lactose to lactitol, and glucose to sorbitol. Sorbitol, xylitol and lactitol are examples of sugar alcohols (also known as polyols). These are, in general, less sweet than sucrose but have similar bulk properties and can be used in a wide range of food products.
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Halostagnicola larsenii is a halophilic, neutrophilic, chemo-organotroph and uses oxygen as its terminal electron acceptor. H. larsenii can utilize a variety of carbohydrates such as fructose, glycerol, lactose, glucose, arabinose, acetate, ribose, starch, maltose, galactose, ribose, xylose, glutamate, and propionate as substrates for growth. Growth substrates were determined through the use of the isolation medium, which contained the substrate being tested along with yeast extract. Additionally, H. larsenii undergoes assimilatory nitrate reduction to nitrite to ammonia.
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T. lanuginosis is unable to utilize cellulose because it does not produce a cellulase, but it is well adapted to using other complex carbon sources such as hemicellulose. It is capable of growing commensally by using sugars released when cellulose is hydrolyzed by a cellulolytic partner. The hydrolytic products of cellulose and hemicellulose - glucose, xylose and mannose, are transported using the same proton-driven symport. This transport is constitutive, specific, and carrier- mediated, and its sensitivity is temperature dependent.
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O-Man sugars separate two domains of the protein, required to connect the extracellular and intracellular regions to anchor the cell in position. Ribitol, xylose and glucuronic acid can be added to this structure in a complex modification that forms a long sugar chain. This is required to stabilise the interaction between α-dystroglycan and the extracellular basement membrane. Without these modifications, the glycoprotein cannot anchor the cell which leads to congenital muscular dystrophy (CMD), characterised by severe brain malformations.
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They are in substantially equal amounts. To verify the completion of the fermentation they can be quantified by chemical assay (glucose and fructose are "reducing" sugars that react with an alkaline copper solution called Fehling's solution), an enzymatic method, or by infrared spectroscopy. Other sugars are not fermentable at all. After consumption by the yeast, the ratio of non- fermentable sugars (the ones that are not consumed by yeast: arabinose and xylose) is between 0.5 and 1.7 grams per litre.
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The cells of Vulcanisaeta are straight to slightly curved rods, which range from 0.4 to 0.6 µm in width. In some cases, the cells are branched or bear spherical bodies at the terminals. The archaeon utilizes maltose, starch, malate, yeast extract, peptone, beef extract, casamino acids and gelatin as carbon sources, cannot utilize D-arabinose, D-fructose, lactose, sucrose, D-xylose, acetate, butyrate, formate, fumarate, propionate, pyruvate, succinate, methanol, formamide, methylamine or trimethylamine. As electron acceptors, the organism uses sulfur and thiosulfate.
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Fruit of Brabejum stellatifolium No conclusive studies have been carried out on the chemical substances present in this broad family. The genera Protea and Faurea are unusual as they use xylose as the main sugar in their nectar and as they have high concentrations of polygalactol, while sucrose is the main sugar present in Grevillea. Cyanogenic glycosides, derived from tyrosine, are often present, as are proanthocyanidines (delphinidin and cyanidin), flavonols (kaempferol, quercetin and myricetin) and arbutin. Alkaloids are usually absent.
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Ester linkages arise between oxidized sugars, the uronic acids, and the phenols and phenylpropanols functionalities of the lignin. To extract the fermentable sugars, one must first disconnect the celluloses from the lignin, and then use acid or enzymatic methods to hydrolyze the newly freed celluloses to break them down into simple monosaccharides. Another challenge to biomass fermentation is the high percentage of pentoses in the hemicellulose, such as xylose, or wood sugar. Unlike hexoses such as glucose, pentoses are difficult to ferment.
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Tatakin (4-methoxyisoscutellargin), takakin 8-O-glucoside, takakin 7-O-glucoside, sesamin, chrysophanol, emodin, parietin, bucegin 7-O-glucoside, isoscutellarein, isoscutellarein 7-O-glucoside, methoxsalen, aesculetin, estrone, scopoletin, phytosterols (a mixture of β-sitosterol, stigmasterol and campesterol) and α-amyrin were extracted from G. bruguieri. The so-called moghatin is a biflavone that has been uniquely discovered in moghat. Seeds contain around 19.5% protein, 5.0% mucilage, arabinose (1.8%) and glucuronic acid (14.6%). Both roots and seeds contain rhamnose, xylose, mannose and galacturonic acid.
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Computing methods have been used to design a protein with a novel fold, named Top7, and sensors for unnatural molecules. The engineering of fusion proteins has yielded rilonacept, a pharmaceutical that has secured Food and Drug Administration (FDA) approval for treating cryopyrin-associated periodic syndrome. Another computing method, IPRO, successfully engineered the switching of cofactor specificity of Candida boidinii xylose reductase. Iterative Protein Redesign and Optimization (IPRO) redesigns proteins to increase or give specificity to native or novel substrates and cofactors.
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By the time of harvest, between 15 and 25% of the grape will be composed of simple sugars. Both glucose and fructose are six-carbon sugars but three-, four-, five- and seven-carbon sugars are also present in the grape. Not all sugars are fermentable, with sugars like the five-carbon arabinose, rhamnose and xylose still being present in the wine after fermentation. Very high sugar content will effectively kill the yeast once a certain (high) alcohol content is reached.
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Xylan can be converted in xylooligosaccharides by chemical hydrolysis using acids or by enzymatic hydrolysis using endo-xylanases. Some enzymes from yeast can exclusively converts xylan into only xylooligosaccharides-DP-3 to 7. Xylan is a major components of plant secondary cell walls which is a major source of renewable energy especially for second generation biofuels. However, xylose (backbone of xylan) is a pentose sugar that is hard to ferment during biofuel conversion because microorganisms like yeast cannot ferment pentose naturally.
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In the late 1980s R. planticola was genetically modified by inserting a plasmid from Zymomonas mobilis. This plasmid codes for the enzyme pyruvate decarboxylase which, along with alcohol dehydrogenase already present in the bacteria allow it to produce ethanol. The bacteria already does produce ethanol when metabolizing hexoses and pentoses, but very inefficiently. R. planticola was chosen to receive this gene as it already had metabolic pathways to breakdown pentose sugars such as xylose, which is a main component of agricultural and forest residues.
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Microcystis floating colonies in an Erlenmeyer flask. As the etymological derivation implies, Microcystis is characterized by small cells (a few micrometers in diameter), possessing gas filled vesicles (also lacking individual sheaths). The cells are usually organized into colonies (macroscopic aggregations of which are visible with the naked eye) that begin in a spherical shape, losing coherence to become perforated or irregularly shaped over time. These colonies are bound by a thick mucilage composed of complex polysaccharide compounds, including xylose, mannose, glucose, fucose, galactose, rhamnose, among other compounds.
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The sweetness of lactose is 0.2 to 0.4, relative to 1.0 for sucrose. For comparison, the sweetness of glucose is 0.6 to 0.7, of fructose is 1.3, of galactose is 0.5 to 0.7, of maltose is 0.4 to 0.5, of sorbose is 0.4, and of xylose is 0.6 to 0.7. When lactose is completely digested in the small intestine, its caloric value is 4 kcal/g, or the same as that of other carbohydrates. However, lactose is not always fully digested in the small intestine.
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Structures of heparan sulphate and keratan sulphate, formed by the addition of xylose or GalNAc sugars, respectively, onto serine and threonine residues of proteins. Proteoglycans consist of a protein with one or more sugar side chains, known as glycosaminoglycans (GAGs), attached to the oxygen of serine and threonine residues. GAGs consist of long chains of repeating sugar units. Proteoglycans are usually found on the cell surface and in the extracellular matrix (ECM), and are important for the strength and flexibility of cartilage and tendons.
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In addition to cellulose, β-glucosidases can cleave xylose, mannose and galactose. In white-rot fungi such as Phanerochaete chrysosporium, expression of manganese-peroxidase is induced by the presence of manganese, hydrogen peroxide and lignin, while laccase is induced by availability of phenolic compounds. Production of lignin-peroxidase and manganese-peroxidase is the hallmark of basidiomycetes and is often used to assess basidiomycete activity, especially in biotechnology applications. Most white-rot species also produce laccase, a copper-containing enzyme that degrades polymeric lignin and humic substances.
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Studies have demonstrated that a plant-based diet can be just as edible and palatable as animal-based diets for dogs. Odiferous ingredients that enhance the smell of the food increase palatability, and examples include nutritional yeast, vegetable oil, nori (seaweed), as well as spirulina. Additionally, certain ingredients can be combined to create a palatable flavour. An example is the synergistic combination of hydrolyzed vegetable protein and xylose, as well as a combination of substances derived from glucose, garlic powder, and nature- identical, non-meat chicken flavouring.
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The cells of these species are covered in a thin layer of glycoprotein capsular material that has a gelatin-like consistency, and that among other functions, serves to help extract nutrients from the soil. The C. neoformans capsule consists of several polysaccharides, of which the major one is the immunomodulatory polysaccharide called glucuronoxylomannan (GXM). GXM is made up of the monosaccharides glucuronic acid, xylose and mannose and can also contain O-acetyl groups. The capsule is functioning as the major virulence factor in cryptococcal infection and disease.
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The resulting solution is filtered to remove protein, then using activated carbon, and then demineralized using ion- exchange resins. The purified solution is then run over immobilized xylose isomerase, which turns the sugars to ~50–52% glucose with some unconverted oligosaccharides and 42% fructose (HFCS 42), and again demineralized and again purified using activated carbon. Some is processed into HFCS 90 by liquid chromatography, and then mixed with HFCS 42 to form HFCS 55. The enzymes used in the process are made by microbial fermentation.
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Figure 1: Biosynthesis of α-tomatine (26) and other steroidal glycoalkaloids in Solanaceae species. Figure 2: Mechanism of membrane disruption by glycoalkaloids Alpha-tomatine (α-tomatine) belongs to the compound group steroidal glycoalkaloids. These compounds consist of an aglycon, which is a cholesterol derivative, and a carbohydrate chain, which in the case of α-tomatine consists of two d-glucose units, a d-galactose unit, and a d-xylose unit. In α-tomatine, the tetrasaccharide called lycotetraose is attached to the O-3 of the steroidal aglycone.
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Major issues of the use of glucose isomerase involve its inactivation at higher temperatures and the requirement for a high pH (between 7.0 and 9.0) in the reaction environment. Moderately high temperatures, above 70 °C, increase the yield of fructose by at least half in the isomerization step. The enzyme requires a divalent cation such as Co2+ and Mg2+ for peak activity, an additional cost to manufacturers. Glucose isomerase also has a much higher affinity for xylose than for glucose, necessitating a carefully controlled environment.
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Glycosyltransferases that use non-nucleotide donors such as dolichol or polyprenol pyrophosphate are non-Leloir glycosyltransferases. Mammals use only 9 sugar nucleotide donors for glycosyltransferases: UDP-glucose, UDP-galactose, UDP-GlcNAc, UDP-GalNAc, UDP- xylose, UDP-glucuronic acid, GDP-mannose, GDP-fucose, and CMP-sialic acid. The phosphate(s) of these donor molecules are usually coordinated by divalent cations such as manganese, however metal independent enzymes exist. Many glycosyltransferases are single-pass transmembrane proteins, and they are usually anchored to membranes of Golgi apparatusTransferases in Membranome database.
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In enzymology, a xyloglucan 6-xylosyltransferase () is an enzyme that catalyzes the chemical reaction in which an alpha-D-xylosyl residue is transferred from UDP-D-xylose to a glucose residue in xyloglucan, being attached by an alpha-1,6-D-xylosyl-D-glucose bond. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is UDP-D-xylose:xyloglucan 1,6-alpha-D- xylosyltransferase. Other names in common use include uridine diphosphoxylose- xyloglucan 6alpha-xylosyltransferase, and xyloglucan 6-alpha-D- xylosyltransferase.
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The cells range in shape from egg-shaped, ellipsoidal, to elongated, measuring 2.5–5.0 by 5.0–15.0 µm, and occurring singly, doubly, or in groups of four. Asymmetrical blastoconidia are borne on short sterigmata, and measure 2.0–5.0 by 3.0–7.0 µm. The optimal growth temperature for the fungus occurs at a range of ; growth stops at . Like other Sporobolomyces species, S. koalae has coenzyme Q10 as its major ubiquinone, it lacks the monosaccharide xylose in whole-cell hydrolysates, and it cannot ferment sugars.
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Rhamnogalacturonan-II (RG-II) is a complex polysaccharide termed a pectin that is found in the primary walls of dicotyledenous and monocotyledenous plants and gymnosperms. RG-II is also likely to be present in the walls of some lower plants (ferns, horsetails, and lycopods). Its structure is conserved across vascular plants. RG-II is composed of 12 different glycosyl residues including D-rhamnose, apiose, D-galactose, L-galactose, Kdo, galacturonic acid, L-arabinose, xylose, and L-aceric acid, linked together by at least 21 distinct glycosidic linkages.
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For fuel ethanol production, complete metabolism of complex combinations of sugars in E. coli by synthetic biocatalysts is necessary. Deletion of the methylglyoxal synthase gene in E. coli increases fermentation rate of ethanogenic E. coli by promoting the co-metabolism of sugar mixtures containing the five principal sugars found in biomass (glucose, xylose, arabinose, galactose, and mannose). This suggests that MGS production of methylglyoxal plays a role in controlling expression of sugar-specific transporters and catabolic genes in native E.coli. MGS also has industrial importance in the production of lactate, hydroxyacetone (acetol), and 1,2-propandiol.
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Capsulan has been found to be mostly carbohydrate (70%) with some protein and sulfur. The main sugars making up the carbohydrate are galactose and glucose while other sugars such as xylose, arabinose and mannose are also present in smaller quantities. Myklestad, 1999, Phytoplankton extracellular production and leakage with considerations on the polysaccharide accumulation Sugar acids are common in plant and algal polysacchride but there is disagreement in the literature concerning capsulan's sugar acid content. Kurano claims that capsulan contains none, while Myklestad maintains that both galacturonic and glucuronic acids are present.
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Neurons use the presence of extracellular matrix molecules as clues whether to promote or suppress extension of axons. Chondroitin sulfate proteoglycans suppress the extension of axons over the glial scar, a barrier which develops after lesioning the spinal cord. Proteoglycans consist of one relatively small protein core and attached large glycosaminoglycan side chains. To block the very formation of these side chains xylosyltransferase (XYLT1) which attaches xylose to a serine of the protein core as initiation for glycosaminoglycan chain extension, was targeted by a class of designed DNA molecules.
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Both the structure of humins and the mechanism by which they are synthesized is at present not well defined as the formation and chemical properties of humins will change depending on the process conditions used. Generally, humins have a polymeric furanic-type structure, with hydroxyl, aldehyde and ketone functionalities.van Zandvoort, I., "Towards the Valorisation of Humin By- products: Characterisation, Solubilisation and Catalysis", 2015 However, the structure is dependent on feedstock type (e.g. xylose or glucose) or concentration, reaction time, temperature, catalysts and many other parameters involved in the process.
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Pichia stipitis (aka Scheffersomyces stipitis) is a species of yeast, belonging to the "CUG Clade" of ascomycetous yeasts. This is a group of fungi that substitute serine for leucine when the CUG codon is encountered. S. stipitis is distantly related to brewer's yeast, Saccharomyces cerevisiae, which uses the conventional codon system. Found, among other places, in the guts of passalid beetles, S. stipitis is capable of both aerobic and oxygen limited fermentation, and has the highest known natural ability of any yeast to directly ferment xylose, converting it to ethanol, a potentially economically valuable trait.
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1-propanol is produced from propionaldehyde, produced from ethene and carbon monoxide. Xylitol, a polyol, is produced by hydrogenation of the sugar xylose, an aldehyde. Primary amines can be synthesized by hydrogenation of nitriles, while nitriles are readily synthesized from cyanide and a suitable electrophile. For example, isophorone diamine, a precursor to the polyurethane monomer isophorone diisocyanate, is produced from isophorone nitrile by a tandem nitrile hydrogenation/reductive amination by ammonia, wherein hydrogenation converts both the nitrile into an amine and the imine formed from the aldehyde and ammonia into another amine.
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Pectins, also known as pectic polysaccharides, are rich in galacturonic acid. Several distinct polysaccharides have been identified and characterised within the pectic group. Homogalacturonans are linear chains of α-(1–4)-linked D-galacturonic acid. Substituted galacturonans are characterized by the presence of saccharide appendant residues (such as D-xylose or D-apiose in the respective cases of xylogalacturonan and apiogalacturonan) branching from a backbone of D-galacturonic acid residues. Rhamnogalacturonan I pectins (RG-I) contain a backbone of the repeating disaccharide: 4)-α-D-galacturonic acid-(1,2)-α-L- rhamnose-(1.
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Pectin is the soluble polymeric material in the pulp of oranges, which contains 75% of carboxyl of arabinose and galactose. Pectic compounds are complex heteropolysaccharides in that their chemical composition includes a chain structure of axial-axial α-1.4-linked d-galacturonic acid unit along with blocks of L-rhamnose regions that have side chains of arabinose, galactose, and xylose. Pectin methyl-esterase is the enzyme responsible for hydrolyzing carboxymethyl esters and liberating free carboxyl groups and methyl alcohols. The free carboxyl groups interact with cations to form insoluble pectic acid divalent metal ion complexes.
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In addition, a candy bar included in the food supply melted from high cabin temperatures (up to 102 °F). By the end of the second orbit, he informed Mercury Control that most of the food was a mess and he would avoid touching it for the rest of the flight aside from taking a xylose capsule. With each orbit sunrise, Carpenter also saw the "fireflies", though he observed them to be more like snowflakes. He also noted that the particles did not seem to be truly luminous, and varied in size, brightness, and color.
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Lingonberry jam on toast Jam refers to a product made of whole fruit cut into pieces or crushed, then heated with water and sugar until it reaches "jelling" or "setting" point, achieved through the action of natural or added pectin, then sealed in containers. Pectin is mainly D-galacturonic acid connected by α (1–4) glycosidic linkages. The side chains of pectin may contain small amounts of other sugars such as L-fructose, D-glucose, D-mannose, and D-xylose. In jams, pectin thickens the final product via cross-linking of the large polymer chains.
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All Blastobotrys species, including B. elegans, can grow on cellobiose, D-galactose, D-glucitol, D-glucose, D-mannitol, D-xylose, erythritol, glycerol, ribitol and trehalose. Therefore, when only looking at growth tests, it is very challenging to differentiate B. elegans from other Blastobotrys species. It is worth mentioning, that B. elegans also grows on adenine, arbutin, D-ribose, ethanol, ethylamine, glycine, isobutanol, lactose, n-Hexadecane, maltose, succinate and uric acid. It is unable to grow on D-arabinose, inositol, isoleucine, L-rhamnose, lactate, leucine, melezitose, melibiose, methyl-α-D-glucopyranoside, putrescine, raffinose and sucrose.
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Xylan is used in different ways as part of our daily lives. For example, the quality of cereal flours and the hardness of dough are largely affected by the amount of xylan thus, playing a significant role in bread industry. The main constituent of xylan can be converted into xylitol (a xylose derivative) which is used as a natural food sweetener, which helps to reduce dental cavities and acts as a sugar substitute for diabetic patients. It has many more applications in the livestock industry, because poultry feed has a high percentage of xylan.
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The yeast cells, after growth on glucose-peptone-yeast extract broth culture for three days at , are egg-shaped to elongated, measuring 3–11 by 1–3.5 µm. They occur singly, in budding pairs, or as short pseudohyphae. The yeast can assimilate the following carbon sources: glucose, galactose, sucrose, L-arabinose, cellobiose, maltose, trehalose, lactose, D-xylose, rhamnose, isomaltulose, melibiose, melezitose; mannitol, sorbitol, glycerol, erythritol; N-acetyl glucosamine, 2-ketogluconate, α-methyl-D-glucoside, levulinate and glucosamine. The yeast grew at a variety of temperatures between , but no growth was observed at or .
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The most primary metabolic activity of these microorganisms in sourdough is to produce acid and carbon dioxide; gas production is necessary for the dough leavening if yeast is not added. Lactobacillus pontis is capable of using fructose as a carbon source and convert stoichiometrically convert fructose to lactic acid and ethanol. However, when maltose is present, they use it chiefly as an electron acceptor, and fructose is reduced to mannitol. It can also metabolize ribose, D-raffinose, and gluconate, but cannot use glucose, L-arabinose, D-xylose, galactose, aesculin, lactose or melibiose.
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C. albidosimilis reproduces through budding, and it does not appear s though this species reproduces through any sexual means. When mature, the cell size is approximately 4.9μm to 6.6μm. C. albidosimilis can use L-arabinose, cellobiose, citrate at pH 6.0, ethanol, D-glucitol, gluconate at pH 5.8, glucuronate at pH 5.5, myo-inositol, lactose, maltose, mannitol, melezitose, α-methylglucoside, L-rhamnose, salicin, soluble starch, succinate at pH 5.5, sucrose and xylose as sole carbon sources. This cell can also use L-lysine, nitrate and cadaverine as sole nitrogen sources.
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On the microscopic level the cells appear globose to ovate and are capsulated. Occasionally the cells have been seen to create chains of four to five cells. When grown, it does not require vitamins, but its growth is weakened by the presence of ammonium sulfate. It is able to assimilate alpha-methyl-D- glucoside, Ca-2-keto-gluconate, cellobiose, D-arabinose, D-mannitol, D-sorbitol, D-xylose, galactose, glucose, K-5-keto-gluconate- K-gluconate, lactose, L-arabinose, L-rhamnose, maltose, melezitose, i-inositol, raffinose, salicin and trehalose.
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Snf3 is homologous to multiple sugar transporters, it shares high similarity to the glucose transporters of rat brain cells and human HepG2 hepatoma cells, as well as to the arabinose and xylose transporters (AraE and XylE) of Escherichia coli.Celenza JL, Marshall-Carlson L, Carlson M (1988). The yeast SNF3 gene encodes a glucose transporter homologous to the mammalian protein. PNAS 85, 2130-2134 Based on this homology and on genetic studies, Snf3 was initially thought to be a high affinity glucose transporter. Later, it was found that Snf3 is not a glucose transporter, but rather a high affinity glucose sensor.
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Salmonella spp appear to be yellow or colourless colonies, often with a dark centre. As there are many bacteria that also look like Salmonella on DCA, it is widely recommended that more selective agars are used for the identification of Salmonella, namely xylose lysine deoxycholate (XLD) agar. This growth medium is heat-sensitive and should be poured and cooled as soon as possible after addition of the deoxycholate, otherwise it tends to become very soft and difficult to handle. It has a pH of approximately 7.3, and when poured and cooled, appears light to dark pink in colour.
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Among finding cellulases and hemicellulases, other enzymes such as protease, urease, ribonuclease, pectate lyase, and polygalacturonase are found in cultural media of R. oryzae. Besides producing a number of enzymes, it can also produce a number of organic acids, alcohol, and esters. Cellulases in R. oryzae can be applied to biotechnology, in food, brewery and wine, animal feed, textiles and laundry, pulp and paper industries, and agriculture. R. oryzae can convert both glucose and xylose under aerobic conditions into pure L (+)-lactic acids with by-products such as xylitol, glycerol, ethanol, carbon dioxide and fungal biomass.
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In the late 1950s, scientists at Clinton Corn Processing Company of Clinton, Iowa, tried to turn glucose from corn starch into fructose, but the process was not scalable. In 1965–1970 Yoshiyuki Takasaki, at the Japanese National Institute of Advanced Industrial Science and Technology (AIST) developed a heat-stable xylose isomerase enzyme from yeast. In 1967, the Clinton Corn Processing Company obtained an exclusive license to manufacture glucose isomerase derived from Streptomyces bacteria and began shipping an early version of HFCS in February 1967. In 1983, the FDA approved HFCS as Generally Recognized as Safe (GRAS), and that decision was reaffirmed in 1996.
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Another chemical extracted from the species was an acidic polysaccharide (made up of mostly mannose, glucose, glucuronic acid and xylose) which showed anticoagulant properties. The article concluded that "the polysaccharides from these mushrooms may constitute a new source of compounds with action on coagulation, platelet aggregation and, perhaps, on thrombosis". Another study reported that the species may be effective in stopping platelet binding in vitro, with possible uses regarding hypercholesterolemia. Research has shown that A. auricula-judae can be used to lower cholesterol levels generally, and, in particular, is one of two fungi shown to reduce the level of bad cholesterol.
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An Indian study of seven bee species and 9 plant species found 45 yeast species from 16 genera colonise the nectaries of flowers and honey stomachs of bees. Most were members of the genus Candida; the most common species in honey bee stomachs was Dekkera intermedia, while the most common species colonising flower nectaries was Candida blankii. Although the mechanics are not fully understood, it was found that A. indica flowers more if Candida blankii is present. In another example, Spathaspora passalidarum, found in the digestive tract of scarab beetles, aids the digestion of plant cells by fermenting xylose.
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This intermediate can be converted into a terminal epoxide by usage of classical synthetical operations, such as introducing acetic acid or substitution reactions with tosylates. Next, a dithiane derived anion interacts to form an alcohol. The following step involves introducing an acidic sidechain on the C.9 hydroxyl group. This carboxylic, acidic side group is made of xylose and arabidose. The introduction is realized by protecting the C.29 and C.30 hydroxylgroups with respectively p-methoxybenzyl (MPM) and benzyloxymethyl (BOM), activating the sidechain with acid chloride, and subsequently replacing the C.30 protecting group with a more stable one, tert- butyldiphenylsilyl (TBDPS).
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All monosaccharides are reducing sugars because they either have an aldehyde group (if they are aldoses) or can tautomerize in solution to form an aldehyde group (if they are ketoses). This includes common monosaccharides like galactose, glucose, glyceraldehyde, fructose, ribose, and xylose. Many disaccharides, like cellobiose, lactose, and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are nonreducing disaccharides since neither of the rings is capable of opening.
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The cells of H. utahensis are extremely pleomorphic, exhibiting any shape from irregular coccoid or ellipsoid to triangular, club-shaped or rod-shaped forms. The rod-shaped and ellipsoid cells are 2-10 by 0.5-1 µm and 1-2 by 1 µm in size, respectively, and the spherical cells have a diameter of approximately 1 µm. The archaeon uses only a limited range of substrates, such as glucose, xylose, and fructose, for growth, and is unique in its inability to utilize yeast extract or peptone. Other substances that did not stimulate the organism's growth include organic acids, amino acids, alcohols, glycogen, and starch.
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Second generation biofuels use lignocellulosic raw material such as forest residues (sometimes referred to as brown waste and black liquor from Kraft process or sulfite process pulp mills). Third generation biofuels (biofuel from algae) use non-edible raw materials sources that can be used for biodiesel and bioethanol. It has long been recognized that the huge supply of agricultural cellulose, the lignocellulosic material commonly referred to as "Nature's polymer", would be an ideal source of material for biofuels and many other products. Composed of lignin and monomer sugars such as glucose, fructose, arabinose, galactose, and xylose, these constituents are very valuable in their own right.
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There are also key chemical compositional differences between apples and pears; these factors play a crucial role in pre- fermentation and fermentation decisions for perry production. A diagram of a belt press Compared to most apples, pears tend to have more sugar and total phenolic compounds. The main sugars in perry pears are glucose (192 –284 mg/L), xylose (140–176 mg/g), and galacturonic acid (108–118 mg/g). Types of sugar that are present in the juice play an important role in yeast activity and determine the success of fermentation Unlike the juice of apples, pear juice contains significant quantities of unfermentable sugar alcohols, particularly sorbitol.
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C. antarcticus has not been seen to sexually reproduce, but when they do reproduce asexually they do so through budding. Mature cells that have not recently budded typically are 4.0 μm by 7.5 μm, and they do not appear to produce pseudomycelium. C. antarcticus is not able to ferment, but all of its strains use cellobiose, 2-ketogluconate in hemicalcium salt, gluconate at pH 5.8, glucuronate at pH 5.5, maltose, mannitol, melezitose, soluble starch and succinate at pH 5.5 as sole carbon sources. Only certain strains of C. anarcticus can use citrate at pH 6.0, D-glucitol, L-arabinose, raffinose and xylose as sole carbone sources.
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Xyloglucan backbone synthesis is mediated by cellulose synthase-like protein family C (CSLC), particularly glucan synthase, which adds glucose units to the chain. Backbone synthesis of xyloglucan is also mediated in some way by xylosyltransferase, but this mechanism is separate to its transferase function and remains unclear. Xylosyltransferase in its transferase function is, however, utilized for the addition of xylose to the side-chain. Other enzymes utilized for side- chain synthesis of xyloglucan include galactosyltransferase (which is responsible for the addition of galactose and of which two different forms are utilized), fucosyltransferase (which is responsible for the addition of fucose), and acetyltransferase (which is responsible for acetylation).
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Hafnia grows in media containing 2% to 5% NaCl, a pH range of 4.9 to 8.25, and thermal gradients of 4 °C to 44 °C; the optimum temperature for growth has been reported as 35 °C. There is general agreement that almost 100% of Hafnia strains grow on MacConkey, Hektoen enteric, eosin methylene blue, and xylose-lysine-deoxycholate agars, all of which are differential to moderately selective media. On more inhibitory selective media, 25% to 60% of strains fail to grow on Salmonella-Shigella (SS) agar, while 75% to 100% of isolates are inhibited on brilliant green medium. Classic strains of H. alvei are lactose and sucrose negative and as such appear as nonfermenting colonies on enteric isolation media.
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When in 1981 Rob Aalberse from the University of Amsterdam noticed the enormous cross-reactivity of some patients´ sera against virtually any plant and even insects, notably, insect venoms, it took ten years to arrive at a possible structural explanation of this phenomenon. 1991, Japanese researchers determined the structure of the epitope common to horseradish peroxidase and Drosophila neurons as being an asparagine-linked oligosaccharide (N-glycan) containing a xylose and a core-linked α1,3-linked fucose residue. These structural features are not present in humans and animals. Core α1,3-fucose was then found to be relevant for the binding of patients´ IgE to honeybee venom allergens, which contain N-glycans with structural similarities to plant N-glycans.
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Unlike cellulose, hemicelluloses consist of shorter chains – 500–3,000 sugar units. In contrast, 7,000–15,000 glucose molecules comprise each polymer of cellulose. In addition, hemicellulose may be branched polymers, while cellulose is unbranched. Hemicelluloses are embedded in the cell walls of plants, sometimes in chains that form a 'ground' – they bind with pectin to cellulose to form a network of cross-linked fibres. 195x195px Based on the structural difference, like backbone linkages and side groups, as well as other factors, like abundance and distributions in plants, hemicellulose could be characterized into four groups as following: 1) Xylans, 2) Mannans; 3) Mixed linkage β-glucans; 4) Xyloglucans Xylans Xylans usually consist of backbone of β-(1→4)-linked xylose residues.
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Microbiological sources of exoenzymes including amylases, proteases, pectinases, lipases, xylanases, cellulases among others are used for a wide range of biotechnological and industrial uses including biofuel generation, food production, paper manufacturing, detergents and textile production. Optimizing the production of biofuels has been a focus of researchers in recent years and is centered around the use of microorganisms to convert biomass into ethanol. The enzymes that are of particular interest in ethanol production are cellobiohydrolase which solubilizes crystalline cellulose and xylanase that hydrolyzes xylan into xylose. One model of biofuel production is the use of a mixed population of bacterial strains or a consortium that work to facilitate the breakdown of cellulose materials into ethanol by secreting exoenzymes such as cellulases and laccases.
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140x140px Corn syrup is a food syrup which is made from the starch of corn (called maize in many countries) and contains varying amounts of maltose and higher oligosaccharides, depending on the grade. Corn syrup, also known as glucose syrup to confectioners, is used in foods to soften texture, add volume, prevent crystallization of sugar, and enhance flavor. Corn syrup is distinct from high-fructose corn syrup (HFCS), which is manufactured from corn syrup by converting a large proportion of its glucose into fructose using the enzyme D-xylose isomerase, thus producing a sweeter compound due to higher levels of fructose. The more general term glucose syrup is often used synonymously with corn syrup, since glucose syrup in the United States is most commonly made from corn starch.
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The addition of O-fucose by POFUT1 is absolutely necessary for notch function, and, without the enzyme to add O-fucose, all notch proteins fail to function properly. As yet, the manner by which the glycosylation of notch affects function is not completely understood. The O-glucose on notch can be further elongated to a trisaccharide with the addition of two xylose sugars by xylosyltransferases, and the O-fucose can be elongated to a tetrasaccharide by the ordered addition of an N-acetylglucosamine (GlcNAc) sugar by an N-Acetylglucosaminyltransferase called Fringe, the addition of a galactose by a galactosyltransferase, and the addition of a sialic acid by a sialyltransferase. To add another level of complexity, in mammals there are three Fringe GlcNAc-transferases, named lunatic fringe, manic fringe, and radical fringe.
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Like wine yeast, LAB require a carbon source for energy metabolism (usually sugar and malic acid), nitrogen source (such as amino acids and purines) for protein synthesis, and various vitamins (such as niacin, riboflavin, and thiamine) and minerals to assist in the synthesis of enzymes and other cellular components. The source for these nutrients is often found in the grape must itself, though MLF inoculations that run concurrent with alcoholic fermentation risk the yeast outcompeting the bacteria for these nutrients. Towards the end of fermentation, while most of the original grape must resources have been consumed, the lysis of dead yeast cells (the "lees") can be a source for some nutrients, particularly amino acids. Plus, even "dry" wines that have been fermented to dryness still have unfermentable pentose sugars (such as arabinose, ribose and xylose) left behind that can be used by both positive and spoilage bacteria.
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Studies observing unrestricted sugar intake of females correlated sucrose intake level with maximum accumulation of stored energy reserves. In contrast, sucrose intake level does not correlate with decreased activity or changes in senescence. Carbohydrate feedings of female mosquitoes in a laboratory setting indicated that carbohydrates glucose, fructose, mannose, galactose, sucrose, trehalose, melibiose, maltose, raffinose, melizitose, dextrin, mannitol, and sorbitol are most effective to aid survival; arabinose, rhamnose, fucose, sorbose, lactose, cellobiose, inulin, a-methyl mannoside, dulcitol, and inositol are not used by the species; xylose, glycogen, a-methyl glucoside, and glycerol are used but at a slow metabolic rate; and sorbose could not be metabolized. Feeding with glucose allowed for maximum flight speed while other carbohydrates, such as all pentoses, sorbose, lactose, cellobiose, glycogen, inulin, a-methyl mannoside, dulcitol, and inositol were insufficient to allow flight, indicated by a delay in flight after feeding.
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Nomenclature of the aldaric acids is based on the sugars from which they are derived; for example, glucose is oxidized to glucaric acid and xylose to xylaric acid. Unlike their parent sugars, aldaric acids have the same functional group at both ends of their carbon chain; therefore, two different sugars can yield the same aldaric acid (this can be understood by looking at the Fischer projection of a sugar upside down—with normal aldoses, this is a different compound due to the aldehyde function at the top and the hydroxyl function at the bottom, but with aldaric acids, there is a carboxylic acid function on both ends, so upside down and right side up do not matter). For example, D-glucaric acid and L-gularic acid are the same compound (but the first name is preferred, because of D\- prefix). A consequence of this is that some aldaric acids are meso forms with no optical activity despite their multiple chiral centers—this occurs if a sugar and its enantiomer oxidize to the same aldaric acid.
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