PROBING THE ACCEPTOR SPECIFICITY OF BETA-1,4-GALACTOSYLTRANSFERASE FOR THE DEVELOPMENT OF ENZYMATIC-SYNTHESIS OF NOVEL OLIGOSACCHARIDES

beta-1,4-Galactosyltransferase has been investigated with regard to its acceptor specificity and used in the synthesis of galactosides with 5-thioglucose, glucal, deoxynojirimycin, modified N-acetylglucosamine, and glucose derivatives as acceptors. The galactoside products are potentially useful as endoglycosidase or glycosyltransferase inhibitors or as intermediates for the synthesis of complex oligosaccharides. The conformation of each enzyme product has been investigated with NMR; all are shown to possess similar glycosidic torsional angles based on a significant NOE between H-1 of Gal and H-4 of the acceptor. Comparison of the transferase reactions with the beta-1,4-galactosidase-catalyzed galactosyl transfer reactions indicates that the transferase reactions provide exclusively a beta-1,4-glycosidic linkage while the galactosidase reactions predominantly form a beta-1,6-glycosidic linkage.