ALL-AQUEOUS, REGIOSPECIFIC TRANSGLYCOSYLATION SYNTHESIS OF FUCOPYRANOSYL-2-ACETAMIDO-2-DEOXY-D-GLUCOPYRANOSE, A BUILDING-BLOCK FOR THE SYNTHESIS OF BRANCHED OLIGOSACCHARIDES

A transglycosylation reaction, carried out in an aqueous medium and ca talyzed by a crude preparation of alpha-fucosidase (E.C. 3.2.1.51) fro m Aspergillus niger, allowed for the regiospecific synthesis of the di saccharide -fucopyranosyl-2-acetamido-2-deoxy-D-glucopyranose using p- nitrophenyl-alpha-1-fucopyranose as the donor and 2-acetamido-2-deoxy- D-glucopyranose as the acceptor. The chemical identity of the product obtained was demonstrated by HPLC, ion spray mass spectrometry and NMR spectroscopy. Further transglycosylation using a beta-galactosidase ( E.C. 3.2.1.23) yielded the branched oligosaccharide -2-deoxy-3-O-(beta -L-D-fucopyranosyl)-4-O-(beta-D- galactopyranosyl)-D-glucopyranose, i. e., the Lewis(x) antigen. (C) 1997 Academic Press.