Glycosidic bonds in carbohydrates

This group of enzyme (EC 3.2.1-xx) catalyzes the hydrolysis of glycosidic bonds in carbohydrate-carbohydrate or carbohydrate-aglycone (noncarbohydrate moiety) entities. They can be classified in two distinctive groups as they are able to cleave internal or external osidic linkages (Fig. 4) ... 

Edimecheva IP, Kisel RM, Shadyro OI, Kazem K, Murase H, Kagiya T. Homolytic cleavage of the O-glycoside bond in carbohydrates a steady-state radiolysis study. J RadiatRes 2005 46 319-324. 

The monosaccharides in oligo- and polysaccharides are linked by acetal or ketal bonds, called glycosidic bonds in carbohydrate chemistry. These bonds link the aldehyde or ketone site of one monosaccharide and a hydroxyl group of another monosaccharide. Hydrolysis of the glycosidic bonds yields the component monosaccharides. 

Hydrolases Hydrolysis reactions Proteases hydrolyze peptide bonds in proteins. Lipases hydrolyze ester bonds in lipids. Carbohydrases hydrolyze glycosidic bonds in carbohydrates. Phosphatases hydrolyze phosphoester bonds. Nucleases hydrolyze nucleic acids. 

To determine the position of glycosidic bonds in glycosphingolipids, periodate oxidation and methylation are widely used. A characteristic feature of the periodate oxidation of glycosphingolipids is the stability, to oxidation under mild conditions,179 of the D-glucose residue that is located at the beginning of the carbohydrate chain and substituted at 0-4 this seems to be associated with steric hindrance caused by the close location of the lipid moiety. 

Zegota H, von Sonntag C (1977) Radiation chemistry of carbohydrates, XV. OH radical induced scission of the glycosidic bond in disaccharides. Z Naturforsch 32b 1060-1067... 

Other fractions were prepared for carbohydrate analysis by hydrolysis (of the surfactants glycosidic bonds) in 2 N HC1 in sealed ampules for 6 hr at 100°C (ref. 331). Monosaccharide analyses were performed on a programmed Tracor 985 HPLC system employing a Bio-Rad HPX-87C cation-exchange column for monosaccharide separation. 

Even under weakly basic conditions (pH >9) the entire fatty acid, carbohydrate, nucleotide, and phosphate parts can be cleaved from these compounds. While under acidic conditions an attack on the N- or O-glycosidic bonds in nucleopeptides and glycopeptides may occur, resulting in anomerization and even a complete deglycosidation. 

Variations of DNA and RNA polymers are caused by steric interactions between the base and carbohydrate units in combination with hydration. They lead to rotations around the glycosidic bond. In a bird s-eye view down the... 

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