|
Oligosaccharide Nomenclature
Oligosaccharides and polysaccharides are an important class of polymeric carbohydrates found in virtually all living entities. Their structural features make their nomenclature challenging and their roles in living systems make their nomenclature important. Oligosaccharides Oligosaccharides are carbohydrates that are composed of several monosaccharide residues joined through glycosidic linkage, which can be hydrolyzed by enzymes or acid to give the constituent monosaccharide units. While a strict definition of an oligosaccharide is not established, it is generally agreed that a carbohydrate consisting of two to ten monosaccharide residues with a defined structure is an oligosaccharide.J. H. Pazur, The Carbohydrates: Chemistry and Biochemistry, 2nd Edition, Academic Press, New York, 1970. Some oligosaccharides, for example maltose, sucrose, and lactose, were trivially named before their chemical constitution was determined, and these names are still used today. Image:Maltose st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbohydrates
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may not be different from ''n''), which does not mean the H has covalent bonds with O (for example with , H has a covalent bond with C but not with O). However, not all carbohydrates conform to this precise stoichiometric definition (e.g., uronic acids, deoxy-sugars such as fucose), nor are all chemicals that do conform to this definition automatically classified as carbohydrates (e.g. formaldehyde and acetic acid). The term is most common in biochemistry, where it is a synonym of saccharide (), a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides, the smallest (lower molecular weight) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemistry (journal)
''Biochemistry'' is a peer-reviewed academic journal in the field of biochemistry. Founded in 1962, the journal is now published weekly by the American Chemical Society, with 51 or 52 annual issues. The journal's 2015 impact factor was 2.876, and it received a total of 79,348 citations in 2015.''Biochemistry'': About (accessed May 24, 2017) The previous editor-in-chief was Richard N. Armstrong () (2004–16). After his death, ( |
Monosaccharide
Monosaccharides (from Greek ''monos'': single, '' sacchar'': sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. They are usually colorless, water-soluble, and crystalline solids. Contrary to their name (sugars), only some monosaccharides have a sweet taste. Most monosaccharides have the formula (though not all molecules with this formula are monosaccharides). Examples of monosaccharides include glucose (dextrose), fructose (levulose), and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch). The table sugar used in everyday vernacular is itself a disaccharide sucrose comprising one molecule of each of the two monosaccharides D-glucose and D-fructose. Each carbon atom that supports a hydroxyl group is chiral, except those at the end of the chain. This gives rise to a number of isomeric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbohydrate Conformation
Carbohydrate conformation refers to the overall three-dimensional structure adopted by a carbohydrate (saccharide) molecule as a result of the through-bond and through-space physical forces it experiences arising from its molecular structure. The physical forces that dictate the three-dimensional shapes of all molecules—here, of all monosaccharide, oligosaccharide, and polysaccharide molecules—are sometimes summarily captured by such terms as " steric interactions" and " stereoelectronic effects" (see below). Saccharide and other chemical conformations can be reasonably shown using two-dimensional structure representations that follow set conventions; these capture for a trained viewer an understanding of the three-dimensional structure via structure drawings (see organic chemistry article, and "3D Representations" section in molecular geometry article); they are also represented by stereograms on the two dimensional page, and increasingly using 3D display technologies on compu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligosaccharide
An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sugars). Oligosaccharides can have many functions including cell recognition and cell adhesion. They are normally present as glycans: oligosaccharide chains are linked to lipids or to compatible amino acid side chains in proteins, by ''N''- or ''O''-glycosidic bonds. ''N''-Linked oligosaccharides are always pentasaccharides attached to asparagine via a beta linkage to the amine nitrogen of the side chain.. Alternately, ''O''-linked oligosaccharides are generally attached to threonine or serine on the alcohol group of the side chain. Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrins or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteropolysaccharide Struct
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes as catalyst, which produces constituent sugars ( monosaccharides, or oligosaccharides). They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch, glycogen and galactogen and structural polysaccharides such as cellulose and chitin. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these macromolecules can have distinct properties from their monosaccharide building blocks. They may be amorphous or even insoluble in water. When all the monosaccharides in a polysaccharide are the same type, the polysaccharide is called a homopolysaccharide or homoglycan, but when more t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homopolysaccharide Struct
Homopolysaccharides are polysaccharides composed of a single type of sugar monomer. For example, cellulose is an unbranched homopolysaccharide made up of glucose monomers connected via beta-glycosidic linkages; glycogen is a branched form, where the glucose monomers are joined by alpha-glycosidic linkages. Depending upon the molecules attached that are of the following types 1. Glucan - A polysaccharide of glucose 2. Fructan - A polysaccharide of fructose 3. Galactan - A polysaccharide of galactose 4. Araban - A polysaccharide of arabinose 5. Xylan - A polysaccharide of xylose Xylose ( grc, ξύλον, , "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 gro ... Champe, Harvey, Ferrier. Biochemistry 4th Edition. 2008. 90. References Polysaccharides {{polymer-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactan
Galactan (galactosan) is a polysaccharide consisting of polymerized galactose. In general, galactans in natural sources contain a core of galactose units connected by α(1→3) or α(1→6), with structures containing other monosaccharides as side-chains. Galactan derived from '' Anogeissus latifolia'' is primarily α(1→6), but galactan from acacia trees is primarily α(1→3). '' Halymenia durvillei'' is a red seaweed (algae) with a great potential as sulphated galactan producer. Several other alga species also contain galactans. Including '' Carpopeltis .I.J. Miller and J. Mollion, Evaluation of the structures of galactans from ''Carpopeltis'' sp. a member of the Halymeniales in the western Indian Ocean, Bot. Mar., 49 (2006) 79-85 See also * Agar * Galactooligosaccharide Galactooligosaccharides (GOS), also known as oligogalactosyllactose, oligogalactose, oligolactose or transgalactooligosaccharides (TOS), belong to the group of prebiotics. Prebiotics are defined as non-di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactose
Galactose (, '' galacto-'' + '' -ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as 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 ''galaktos'' (of milk) 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. Structure and isomerism Gal ... [...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 comprise 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 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mannose
Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation are associated with mutations in enzymes involved in mannose metabolism. Mannose is not an essential nutrient; it can be produced in the human body from glucose, or converted into glucose. Mannose provides 2–5 kcal/g. It is partially excreted in the urine. Etymology The root of both "mannose" and "mannitol" is manna, which the Bible describes as the food supplied to the Israelites during their journey in the region of Sinai. Several trees and shrubs can produce a substance called manna, such as the "manna tree" ('' Fraxinus ornus'') from whose secretions mannitol was originally isolated. Structure Mannose commonly exists as two different-sized rings, the pyranose (six-membered) form and the furanose (five-membered) form. Eac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucan
A glucan is a polysaccharide derived from D-glucose, linked by glycosidic bonds. Glucans are noted in two forms: alpha glucans and beta glucans. Many beta-glucans are medically important. They represent a drug target for antifungal medications of the echinocandin class. Types The following are glucans (The α- and β- and numbers clarify the type of O-glycosidic bond and the specific carbons involved): Alpha * dextran, α-1,6-glucan with α-1,3-branches * floridean starch, α-1,4- and α-1,6-glucan * glycogen, α-1,4- and α-1,6-glucan * pullulan, α-1,4- and α-1,6-glucan * starch, a mixture of amylose and amylopectin, both α-1,4- and α-1,6-glucans Beta * cellulose, β-1,4-glucan * chrysolaminarin, β-1,3-glucan * curdlan, β-1,3-glucan * laminarin, β-1,3- and β-1,6-glucan * lentinan, a strictly purified β-1,6:β-1,3-glucan from ''Lentinus edodes'' * lichenin, β-1,3- and β-1,4-glucan * oat beta-glucan, β-1,3- and β-1,4-glucan * pleuran, β-1,3- and β-1,6-gluca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
