Chemoenzymatic synthesis of sialylated oligosaccharides for their evaluation in a polysialyltransferase assay

A series of sialylated β-d-Gal-(1→3)-α-d-GalNAc-octyl containing oligosaccharides representative of those found on mucin type complex O-glycans were synthesized by a chemoenzymatic approach for use in the kinetic characterization of recently cloned polysialyltransferases. Enzymatic incorporation of N-acetylneuraminic acid (sialic acid) into the synthetic acceptors was accomplished by 2,3-(N) and (O)-sialyltransferases to give the target compounds 6–10 in a practical yield.