Monosaccharides sequence analysis

Chemical structure elucidation of the carbohydrate moiety of a glycoprotein is a difficult problem because there is often chain branching and because the individual carbohydrate chains are not always identical. Specific exoglycosidases which release monosaccharide units only from the terminal nonreducing end of the carbohydrate chain are most useful in structural analysis. Among the enzymes available for sequence analysis... 

A number of glycosidic hydrolases have been produced in sufficiently pure form to allow the development of a method of determination of monosaccharide sequences based on these enzymes (Table 6.4). These enzymes will remove specific monosaccharide units linked by specific linkages from the nonreducing end of a polysaccharide. For example, P-galactosidase will remove D-galactosyl residues linking p-glycosidically to polysaccharide. The use of sequential enzymatic hydrolysis is a well-established technique, particularly for the analysis of the carbohydrate residues of macromolecules. 

Establishing the complete structure of oligosaccharides and polysaccharides requires determination of branching positions, the sequence in each branch, the configuration of each monosaccharide unit, and the positions of the glycosidic links—a more complex problem than protein and nucleic acid analysis. 

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