Transfer of D-galactosyl groups to 6-O-substituted 2-acetamido-2-deoxy-D-glucose residues by use of bovine D-galactosyltransferase.

Bovine D-galactosyltransferase was found to transfer D-galactose from UDP-galactose to 6-O-substituted 2-acetamido-2-deoxy-beta-D-glucopyranosides. The resulting 6-O-substituted N-acetyllactosamines were readily synthesized in milligram amounts and conveniently isolated on a reverse-phase support when prepared as the 8-methoxycarbonyloctyl glycosides. The 6-O-substitution tolerated by the enzyme include an alpha-L-fucopyranosyl group and the methyl ester of alpha-linked N-acetylneuraminic acid, but not the free acid itself. The product trisaccharides were characterized by 1H-n.m.r. spectroscopy and fast-atom-bombardment mass spectrometry.