Synthesis of the glycosaminoglycan-protein linkage tetraosyl peptide moieties of betaglycan, which serve as a hexosamine acceptor for enzymatic glycosyl transfer

Two partial sequences of betaglycan, GlcA-Gal-Gal-Xyl-SerGlyAspAsnGly-R (1) R = H and (2) R = PheProGly, were synthesized in a stereocontrolled manner. Both tetraosyl oligopeptides were far better acceptors for β4GalNAcT-I than for α4GlcNAcT-I in vitro, although they also showed appreciable acceptor activity for α4GlcNAcT-I.