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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 ato ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-linked Glycan
The terms glycans and polysaccharides are defined by IUPAC as synonyms meaning "compounds consisting of a large number of monosaccharides linked glycosidically". However, in practice the term glycan may also be used to refer to the carbohydrate portion of a glycoconjugate, such as a glycoprotein, glycolipid, or a proteoglycan, even if the carbohydrate is only an oligosaccharide. Glycans usually consist solely of O-glycosidic linkages of monosaccharides. For example, cellulose is a glycan (or, to be more specific, a glucan) composed of β-1,4-linked D-glucose, and chitin is a glycan composed of β-1,4-linked ''N''-acetyl-D-glucosamine. Glycans can be homo- or heteropolymers of monosaccharide residues, and can be linear or branched. Glycans and proteins Glycans can be found attached to proteins as in glycoproteins and proteoglycans. In general, they are found on the exterior surface of cells. O- and N-linked glycans are very common in eukaryotes but may also be found, al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abequose
Abequose is a hexose and a 3,6-dideoxysugar. It is a constituent of the in O‐specific chains in lipopolysaccharides that occur in certain serotypes of ''Salmonella'' and ''Citrobacter'' bacteria. It is the enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical anti ... of colitose. References External links Hexoses Deoxy sugars {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colitose
Colitose is a mannose-derived 3,6-dideoxysugar produced by certain bacteria. It is a constituent of the lipopolysaccharide. It is the enantiomer of abequose. Biological role Colitose is found in the O-antigen of certain Gram-negative bacteria such as ''Escherichia coli'', ''Yersinia pseudotuberculosis'', ''Salmonella enterica'', ''Vibrio cholerae'', and in marine bacteria such as ''Pseudoalteromonas sp''. The sugar was first isolated in 1958, and subsequently was enzymatically synthesized in 1962. Biosynthesis The biosynthesis of colitose begins with ColE, a mannose-1-phosphate guanylyltransferase that catalyzes the addition of a GMP moiety to mannose, yielding GDP-mannose. In the next step, ColB, an NADP-dependent short-chain dehydrogenase-reductase enzyme, catalyzes the oxidation at C-4 and the removal of the hydroxyl group at C-6. The resulting product, GDP-4-keto-6-deoxymannose, then reacts with the PLP-dependent enzyme GDP-4-keto-6-deoxymannose-3-dehydratase (ColD), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldol Condensation
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to give a conjugated enone. The overall reaction is as follows (where the Rs can be H): Aldol condensations are important in organic synthesis and biochemistry as ways to form carbon–carbon bonds. In its usual form, it involves the nucleophilic addition of a ketone enolate to an aldehyde to form a β-hydroxy ketone, or "aldol" (aldehyde + alcohol), a structural unit found in many naturally occurring molecules and pharmaceuticals. The term ''aldol condensation'' is also commonly used, especially in biochemistry, to refer to just the first (addition) stage of the process—the aldol reaction itself—as catalyzed by aldolases. However, this is formally an addition reaction rather than a condensation reaction because it does not inv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escherichia Coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly found in the lower intestine of warm-blooded organisms. Most ''E. coli'' strains are harmless, but some serotypes ( EPEC, ETEC etc.) can cause serious food poisoning in their hosts, and are occasionally responsible for food contamination incidents that prompt product recalls. Most strains do not cause disease in humans and are part of the normal microbiota of the gut; such strains are harmless or even beneficial to humans (although these strains tend to be less studied than the pathogenic ones). For example, some strains of ''E. coli'' benefit their hosts by producing vitamin K2 or by preventing the colonization of the intestine by pathogenic bacteria. These mutually beneficial relationships between ''E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoside
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of ''Heliconius'' butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body. In formal terms, a glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond. Glycosides can be linked by an O- (an '' O-glycoside''), N- (a '' glycosylamine''), S-(a '' thioglycoside''), or C- (a '' C-glycoside'') glycosidic bond. Accordin ... [...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. E ... [...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 include 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 organism th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avian Influenza Virus
Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds.Chapter Two : Avian Influenza by Timm C. Harder and Ortrud Werner in ''Influenza Report 2006'' CDC has a showing the relationship between dozens of highly varieties of the Z genotype of avian flu virus H5N1 and ancestral strains. The type with the greates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tagatose
Tagatose is a hexose monosaccharide. It is found in small quantities in a variety of foods, and has attracted attention as an alternative sweetener. It is often found in dairy products, because it is formed when milk is heated. It is similar in texture and appearance to sucrose (table sugar):215 and is 92% as sweet,:198 but with only 38% of the calories.:209 Tagatose is generally recognized as safe by the Food and Agriculture Organization and the World Health Organization, and has been since 2001. Since it is metabolized differently from sucrose, tagatose has a minimal effect on blood glucose and insulin levels. Tagatose is also approved as a tooth-friendly ingredient for dental products. Consumption of more than about 30 grams of tagatose in a dose may cause gastric disturbance in some people, as it is mostly processed in the large intestine, similar to soluble fiber.:214 Production Tagatose is a natural sweetener present in only small amounts in fruits, cacao, and dairy prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fuculose
Fuculose or 6-deoxy-tagatose is a ketohexose 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, a .... Fuculose is involved in the process of sugar metabolism. -Fuculose can be formed from -fucose by -fucose isomerase and converted to L-fuculose-1-phosphate by -fuculose kinase. See also * -fuculose-phosphate aldolase * -fuculosekinase References Deoxy sugars Ketohexoses {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
