Use of Glycosidases and Glycosyltransferases in the Synthesis of Complex Oligosaccharides and Their Glycosides

Abstract

This chapter describes recent syntheses of complex oligosaccharides using glycosidases and glycosyltransferases as catalysts. Glycosidases have been used for synthesis of several of the disaccharide sequences of glycoproteins and glycolipids. High yields were obtained by using high substrate concentrations. Thus, the yield of α-galactosidase-catalyzed synthesis of α-linked p-nitrophenyl digalactosides from p-nitrophenyl α-galactopyranoside was about 65% when the initial concentration of the substrate was 1 M, compared to a yield of only about 30% when the initial concentration of substrate was 0.15 M. The sequential use of glycosidases and glycosyltransferases was a convenient way to prepare sialylated trisaccharides. Both sialyltransferase and CMP-sialate synthase were immobilized to tresyl chloride-activated agarose in good yield (about 55%) and used for repeated synthesis with negligible loss of activity.