The use of immobilised glycosyltransferases in the synthesis of sialyloligosaccharides.

The CMP-sialic acids, cytidine 5'-(5-acetamido-3,5-dideoxy-beta-D-glycero-D-galacto-2-nonulopyranosy lonic acid monophosphate) (1) and cytidine 5'-(5-acetamido-9-O-acetyl-3,5-dideoxy-beta-D-glycero-D-galacto-2- nonulopyranosylonic acid monophosphate) (2) were prepared from CMP, phosphoenolpyruvate, N-acetylneuraminic acid or its 9-acetate, and a catalytic amount of ATP in the presence of immobilised pyruvate kinase, nucleoside monophosphate kinase, inorganic pyrophosphatase, and CMP-sialic acid synthetase. CMP-NeuAc (1) was used as a donor of N-acetylneuraminic acid in the reaction catalysed by immobilised porcine liver beta-D-Galp-(1----4)-alpha-D-GlcpNAc-(2----6)-sialyltransferase, alpha-D-Neup5Ac-(2----6)-beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1--- -2)-alpha-D- Man-OMe (5) was obtained on a 0.1-mmol scale by enzymic sialylation of beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----2)-alpha-D-Man-OMe (4), prepared by enzymic galactosylation of beta-D-GlcpNAc-(1----2)-alpha-D-Man-OMe (3). Likewise, using 2, alpha-D-Neup-5,9Ac2-(2----6)-beta-D-Galp-(1----4)-D-GlcpNAc (7) was obtained from N-acetyl-lactosamine (6).