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Hemicellulose
A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all embryophyte, terrestrial plant cell walls. Cellulose is crystalline, strong, and resistant to hydrolysis. Hemicelluloses are branched, shorter in length than cellulose, and also show a propensity to crystallize. They can be hydrolyzed by dilute acid or Base (chemistry), base as well as a myriad of Cellulase, hemicellulase enzymes. Composition Diverse kinds of hemicelluloses are known. Important examples include xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan. Hemicelluloses are polysaccharides often associated with cellulose, but with distinct compositions and structures. Whereas cellulose is derived exclusively from glucose, hemicelluloses are composed of diverse sugars, and can include the five-carbon sugars xylose and arabinose, the six-carbon sugars glucose, mannose and galactose, and the si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellulose
Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most abundant biopolymer, organic polymer on Earth. The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%. Cellulose is mainly used to produce paperboard and paper. Smaller quantities are converted into a wide variety of derivative products such as cellophane and rayon. Conversion of cellulose from energy crops into biofuels such as cellulosic ethanol is under development as a renewable fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton. Cellulose is also greatly affected by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylan
Xylan (; ) ( CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is the third most abundant polysaccharide on Earth, after cellulose and chitin. Composition Xylans are polysaccharides made up of β-1,4-linked xylose (a pentose sugar) residues with side branches of α-arabinofuranose and/or α-glucuronic acids. On the basis of substituted groups xylan can be categorized into three classes i) glucuronoxylan (GX) ii) neutral arabinoxylan (AX) and iii) glucuronoarabinoxylan (GAX). In some cases contribute to cross-linking of cellulose microfibrils and lignin through ferulic acid residues. Occurrence Plant cell structure Xylans play an important role in the integrity of the plant cell wall and increase cell wall recalcitrance to enzymatic digestion; thus, they help plants to defend against herbivores and pathogens (b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabinoxylan
Arabinoxylan is a form of the hemicellulose xylan found in both the primary and secondary cell walls of plants which in addition to xylose contains substantial amounts of another pentose sugar, arabinose.Scheller, H. V., & Ulvskov, P. (2010). Hemicelluloses. ''Annual Review of Plant Biology, 61'', 263-289. doi:10.1146/annurev-arplant-042809-112315 The term arabinoxylan usually refers to feruloyl-arabinoxylan from grasses and other commelinids containing moieties of the phenolic ferulic acid that can undergo oxidative coupling (in the same way as lignin units) forming crosslinks between arabinoxylan chains and with lignin. Whilst arabinose has been found linked to xylan in non-commelinid plants, ferulic acid has not been reported on these and unlike feruloyl-arabinoxylan these arabinoxylans are not monophyletic. The remainder of this article refers to feruloyl-arabinoxylan from cell walls of grasses and other commelinid species. Structure As with all xylan, the backbone of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mannan (polysaccharide)
Mannans are polymers containing the sugar mannose as a principal component. They are a type of polysaccharide found in hemicellulose, a major source of biomass found in higher plants such as softwoods. These polymers also typically contain two other sugars, galactose and glucose. They are often branched (unlike cellulose). Structural diversity Plant mannans have β(1-4) linkages, occasionally with α(1-6) galactose branches, forming galactomannans. They are insoluble and a form of storage polysaccharide. Ivory nut is a source of mannans. An additional type is galactoglucomannan found in soft wood with a mixed mannose/glucose β(1-4) backbone. Many mannans are acetylated and some from marine sources, have sulfate esters side chains. Yeast and some plants such as conjac and salep have a different type of mannans in their cell wall, with a α(1-6) linked backbone and α(1-2) and α(1-3) linked glucose branches, hence "glucomannan". It is water soluble. It is serologically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deoxy Sugar
Deoxy sugars are sugars that have had a hydroxyl group replaced with a hydrogen atom. Examples include: * Deoxyribose, or 2-deoxy-D-ribose, a constituent of DNA * Fucose, or 6-deoxy-L-galactose, main component of fucoidan of brown algae, and present in N-linked glycans * Fuculose, or 6-deoxy-L- tagatose, one of the important components of avian influenza virus particles * Rhamnose, or 6-deoxy-L-mannose, present in plant glycosides In ''Escherichia coli'' bacteria, deoxyribose sugars are synthesized via two different pathways - one pathway involves aldol condensation, whereas the other pathway is conversion of a ribose sugar into a deoxyribose sugar by means of changes on the nucleotide or nucleoside level. Deoxyribose is synthesized through the reduction of ribose. Deoxyribose is derived from the same precursor as ribose being that the reduction of the sugar with the extra hydroxyl group results in the deoxy-sugar, which has its hydroxyl group replaced with a hydrogen atom. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhamnose
Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl- pentose or a 6-deoxy- hexose. Rhamnose predominantly occurs in nature in its L-form as L-rhamnose (6-deoxy-L- mannose). This is unusual, since most of the naturally occurring sugars are in D-form. Exceptions are the methyl pentoses L- fucose and L-rhamnose and the pentose L- arabinose. However, examples of naturally-occurring D-rhamnose are found in some species of bacteria, such as '' Pseudomonas aeruginosa'' and '' Helicobacter pylori''. Rhamnose can be isolated from buckthorn (''Rhamnus''), poison sumac, and plants in the genus ''Uncaria''. Rhamnose is also produced by microalgae belonging to class Bacillariophyceae (diatoms). Rhamnose is commonly bound to other sugars in nature. It is a common glycone component of glycosides from many plants. Rhamnose is also a component of the outer cell membrane of acid-fast bacteria in the ''Mycobacterium'' genus, which includes the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentose
In chemistry, a pentose is a monosaccharide (simple sugar) with five carbon atoms. The chemical formula of many pentoses is , and their molecular weight is 150.13 g/mol.-Ribose . PubChem compound webpage, accessed on 2010-02-06. Pentoses are very important in . Ribose is a constituent of , and the related molecule, deoxyribose, is a constituent of DNA. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucuronic Acid
Glucuronic acid (GCA, from ) is a uronic acid that was first isolated from urine (hence the name "uronic acid"). It is found in many natural gum, gums such as gum arabic ( 18%), xanthan, and kombucha tea and is important for the metabolism of microorganisms, plants and animals. Properties Glucuronic acid is a sugar acid derived from glucose, with its sixth carbon atom oxidized to a carboxylic acid. In living beings, this primary oxidation occurs with Uridine diphosphate glucose, UDP-α-D-glucose (UDPG), not with the free sugar. Glucuronic acid, like its precursor glucose, can exist as a linear (carboxo-)aldohexose ( 60,000 are too large for renal excretion and will be excreted with bile into the intestine. Neonates are deficient in this conjugating system, making them particularly vulnerable to drugs such as chloramphenicol, which is inactivated by the addition of glucuronic acid, resulting in gray baby syndrome. Bilirubin is excreted in the bile as bilirubin diglucuronid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galacturonic Acid
-Galacturonic acid is a sugar acid, an oxidized form of -galactose. It is the main component of pectin, in which it exists as the polymer polygalacturonic acid. In its open form, it has an aldehyde group at C1 and a carboxylic acid group at C6. Other oxidized forms of -galactose are -galactonic acid (carboxylic group at C1) and ''meso''-galactaric acid ( mucic acid) (carboxylic groups at C1 and C6). It is also a uronic acid or hexuronic acid. Naturally occurring uronic acids are -glucuronic acid, -galacturonic acid, - iduronic acid and -mannuronic acid Mannuronic acid is a uronic acid monosaccharide that can be derived from mannose. Along with -guluronic acid, -mannuronic acid is a component of alginic acid, a polysaccharide found predominantly in brown algae Brown algae (: alga) are a lar .... References {{DEFAULTSORT:Galacturonic acid, D- Uronic acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteropolymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called ''bipolymers''. Those obtained from three and four monomers are called ''terpolymers'' and ''quaterpolymers'', respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all of which are formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, which is used to produce the nylon-12/6/66 copolymer of nylon 12, nylon 6 and n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactose
Galactose (, ''wikt:galacto-, galacto-'' + ''wikt:-ose#Suffix 2, -ose'', ), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweetness, sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecule linked with a glucose molecule forms a lactose molecule. Galactan is a polymeric form of galactose found in hemicellulose, and forming the core of the galactans, a class of natural polymeric carbohydrates. D-Galactose is also known as brain sugar since it is a component of glycoproteins (oligosaccharide-protein compounds) found in Nerve tissue, nerve tissue. Etymology The word ''galactose'' was coined by Charles Weissman in the mid-19th century and is derived from Greek language, Greek , , and the generic chemical suffix for sugars ''-ose''. The etymology is comparable to that of the word ''lactose'' in that both contain roots meaning "milk sugar". Lactose is a disaccharide of galactose plus glucose. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
