GLYCOSIDASE-CATALYZED OLIGOSACCHARIDE SYNTHESIS OF DI-SACCHARIDES, TRI-SACCHARIDES 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 o f N-acetylglucosaminyl and N-acetylgalactosaminyl residues selectively on to the 6-OH group of N-acetylgalactosamine to give the correspondi ng (1-->6)-linked disaccharides 3 and 6 in 26 and 38% yield, respectiv ely, The disaccharide beta-D-GlcpNAc-(1-->6)-beta-D-GalpNAc 3 thus syn thesized 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 b eta-D-Galp-(1-->4)-beta-GlcpNAc-(1-->6)-D-GalpNAc 8 in 48% yield toget her with the tetrasaccharide ta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->6)- D-GalpNAc 9 in 7% yield, With lactose as acceptor, the trisaccharide b eta-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-D-Glcp 12, a growth factor for human intestinal bifidobacteria, is produced in 52% yield.