Glycosidase-catalysed oligosaccharide synthesis of di-, tri- and tetra-saccharides using the N-acetylhexosaminidase from Aspergillus oryzae and the beta-galactosidase from Bacillus circulans

The N-acetylhexosaminidase from Aspergillus oryzae catalyse transfer of N-acetylglucosaminyl and N-acetylgalactosaminyl residues selectively on to the 6-OH group of N-acetylgalactosamine to give the corresponding (1-->6)-linked disaccharides 3 and 6 in 26 and 38% yield, respectively, The disaccharide beta-D-GlcpNAc-(1-->6)-beta-D-GalpNAc 3 thus synthesized acts as acceptor for transfer of a beta-D-galactosyl residue from the corresponding p-nitrophenyl glycoside on to the 4-OH group of the non-reducing unit to give the ovarian cyst fluid mucin fragment beta-D-Galp-(1-->4)-beta-GlcpNAc-(1-->6)-D-GalpNAc 8 in 48% yield together with the tetrasaccharide beta-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->6)-D-GalpNAc 9 in 7% yield, With lactose as acceptor, the trisaccharide beta-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-D-Glcp 12, a growth factor for human intestinal bifidobacteria, is produced in 52% yield.