ABSTRACT
This chapter evaluates the potential of enzymatic in vitro synthesis of mammalian glycoconjugate carbohydrate structures. The oligosaccharide structures of glycoconjugates seldom contain more than 20 residues and are built from relatively few glycosidically linked monosaccharides (L-fucose, D-galactose, D-mannose, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and N-acetylneuraminic (sialic) acid, glucose, and xylose). Human influenza viruses contain a glycoprotein (hemagglutinin) that binds to oligosaccharide sequences containing terminal sialic acid. The chemical synthesis of oligosaccharides is considered to be more complex than that of other biopolymers. Glycosidases are generally classified as endoglycosidases that act on glycosidic linkages within oligo- or polysaccharides and exoglycosidases that are active on terminal linkages and release monosaccharides. A wide variety of aglycon groups are tolerated by most glycosidases, although the kinetic parameters are influenced by the aglycon structure. The three types of glycosidase reactions—hydrolysis, transglycosylation, and reversed hydrolysis—have all been used for the preparation of oligosaccharides.
