Chemoenzymic preparation of a glycoconjugate polymer having a sialyloligosaccharide: Neu5Ac alpha (2-->3)Gal beta (1-->4)GlcNAc.

Water-soluble polyacrylamide having 3'-sialyl N-acetyl-lactosamine [Neu5Ac alpha (2-->3)Gal beta (1-->4)GlcNAc] was enzymatically prepared by stepwise sugar-elongation on a water-soluble GlcNAc-bearing polyacrylamide. It was demonstrated that the flexible GlcNAc branches of the polymer chains allow quantitative galactosylation with bovine galactosyl transferase and partial sialylation by Trypanosoma cruzi trans-sialidase. Unsialylated N-acetyl-lactosamine side chains can be removed with beta-D-galactosidase and N-acetyl-beta-D-glucosaminidase to afford the targeted polymer containing 3'-sialyl N-acetyl-lactosamine.