Synthesis of O-β-D-Galactopyranosyl-(1→3)-O-β-D-Galactopyranosyl-(1→4)-O-β-D-Xylopyranosyl-(1→3)-L-Serine (Gal-Gal-Xyl-Ser)

O-β-D-Galactopyranosyl-(1→3)-O-β-D-galactopyranosy1-(1→4)-O-β-D-xylopyranosyl-(1→3)-L-serine (Gal-Gal-Xyl-Ser) was prepared by a procedure involving the synthesis of a benzoylated galactobiosyl bromide and a xylosylserine derivative with an unsubstituted hydroxyl group at C-4 (3-O-(2, 3-di-O-benzoyl-β-D-xylopyranosyl)-N-carbobenzoxy-L-serine benzyl ester), followed by condensation and deblocking. The structure of the product was confirmed by H- and 13 C-NMR spectroscopy. Upon incubation with an extract of embryonic chick cartilage, the synthetic Gal-Gal-Xyl-Ser served as an acceptor for enzymatic glucuronosyl transfer from UDP-D-glucuronic acid.