TRISACCHARIDE SYNTHESIS BY GLYCOSYL TRANSFER FROM P-NITROPHENYL BETA-D-N-ACETYLGALACTOSAMINIDE ON TO DISACCHARIDE ACCEPTORS CATALYZED BY THE BETA-N-ACETYLHEXOSAMINIDASE FROM ASPERGILLUS-ORYZAE

The beta-N-acetylhexosaminidase from Aspergillus oryzae catalysed the transfer of beta-D-N-acetylgalactosaminyl residues from p-nitrophenyl beta-D-N-acetylglucosaminide on to disaccharide accepters consisting o f thioethyl glycosides of alpha-D-Glc-(1 --> 4)-beta-D-Glc, beta-D-Glc -(1 --> 4)-beta-D-Glc and beta-D-Glc-(1 --> 6)-beta-D-Glc. The princip le of 'anomeric control' was exemplified by the results which showed t hat an alpha-linkage between the units of the acceptor favoured exclus ively the formation of a new (1 --> 4)-linkage, whereas the beta-confi guration in the acceptor led to a mixture of (1 --> 4)- and (1 --> 3)- linked products, as observed for simple glycosides of monosaccharide a ccepters. With the thioethyl beta-lactoside as acceptor, beta-D-Gal(1 --> 6)-beta-D-Gal-(1 --> 4)-beta-D-GlcSEt was formed, owing to the act ion of residual beta-D-galactosidase activity in the N-acetylhexosamin idase on the thioethyl beta-lactoside acting as both donor and accepto r. (C) 1998 Elsevier Science Ltd.