Trisaccharide synthesis by glycosyl transfer from p-nitrophenyl [formula omitted] on to disaccharide acceptors catalysed by the β- N-acetylhexosaminidase from Aspergillus oryzae

Abstract

The β- N-acetylhexosaminidase from Aspergillus oryzae catalysed the transfer of β- d-N- acetylgalactosaminyl residues from p-nitrophenyl β- d-N- acetylglucosaminide on to disaccharide acceptors consisting of thioethyl glycosides of α- d- Glc-(1 → 4)-β- d- Glc , β- d- Glc-(1 → 4)-β- d- Glc and β- d- Glc-(1 → 6)-β- d- Glc . The principle of ‘anomeric control’ was exemplified by the results which showed that an α-linkage between the units of the acceptor favoured exclusively the formation of a new (1 → 4)-linkage, whereas the β-configuration in the acceptor led to a mixture of (1 → 4)- and (1 → 3)-linked products, as observed for simple glycosides of monosaccharide acceptors. With the thioethyl β-lactoside as acceptor, β- d- Gal-(1 → 6)-β- d- Gal-(1 → 4)-β- d- GlcSEt was formed, owing to the action of residual β- d- galactosidase activity in the N-acetylhexosaminidase on the thioethyl β-lactoside acting as both donor and acceptor.