Hydrolysis and other Cleavage of Glycosidic Linkages

Abstract

Cleavage of glycosidic linkages of larger oligo- and polysaccharides is necessary to determine their monosaccharide constituents. Glycosidic linkages may be cleaved in other solvents such as methanol. Methanolysis is usually catalyzed by dry hydrogen chloride. The internal standard must not appear in the samples and must be resolved from other components in the sample, as with any internal standard. It is useful to arrange a review of the literature concerning acid hydrolysis by the type of substrate and then by the type of acid within a substrate. In glycoconjugates the carbohydrate moieties are linked to the protein portion by jty-glycosylic or glycosidic linkages. Methanolysis is carried out with dry hydrogen chloride in anhydrous methanol at elevated temperatures. It is important to work under anhydrous conditions since the presence of water will set up an equilibrium between methyl glycosides and the free forms of sugars in aqueous solutions, leading to very complex mixtures.