Trisaccharide synthesis by glycosyl transfer from p-nitrophenyl beta-D-N-acetylgalactosaminide on to disaccharide acceptors catalysed 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 of 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 principle of 'anomeric control' was exemplified by the results which showed that an alpha-linkage between the units of the acceptor favoured exclusively the formation of a new (1 --> 4)-linkage, whereas the beta-configuration in the acceptor led to a mixture of (1 --> 4)- and (1 --> 3)-linked products, as observed for simple glycosides of monosaccharide accepters. 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 action of residual beta-D-galactosidase activity in the N-acetylhexosaminidase on the thioethyl beta-lactoside acting as both donor and acceptor. (C) 1998 Elsevier Science Ltd