A water-soluble polymer, carrying 0.16 meq of lactose/g was prepared following the copolymerization of 2-nitro-4-(carboxyhydrazido-N-aclyloyl)benzyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-beta-D-glucopyranoside and acrylamide. Subsequently, employing a sialyltransferase-phosphatase system a NeuNAc-residue was transferred photochemical release, the free G(M3)-oligosaccharide [NeuNAc alpha(2-3)Gal beta(1-4)Glc].