ENZYMATIC SYNTHESES OF N-ACETYLLACTOSAMINE AND N-ACETYLALLOLACTOSAMINE BY THE USE OF BETA-D-GALACTOSIDASES

A beta-D-galactosidase from Bacillus circulans induced beta-D-galactopyranosyl transfer from lactose predominantly to a secondary (OH-4) rather than the primary hydroxyl group (OH-6) of 2-acetamido-2-deoxy-D-glucopyranose. 4-O-beta-D-Galactopyranosyl-2-acetamido-2-deoxy-D-glucopyranose (N-acetyllactosamine) was thus readily synthesized on a gram scale and conveniently isolated by chromatography on a column of charcoal-Celite. On the other hand, the glycosyl transfer to the 6-position predominantly was efficiently induced to give 6-O-beta-D-galactopyranosyl-2-acetamido-2-deoxy-D-glucopyranose (N-acetylallolactosamine) by consecutive use of beta-D-galactosidases from Kluyveromyces lactis and B. circulans. These enzyme reactions were efficient enough to allow the one-pot preparation of the desired disaccharides.