CHEMOENZYMATIC SYNTHESIS OF GAL(BETA-1-3)GAL(BETA-1-4)XYL(BETA)-L-SERAND GAL(BETA-1-3)GAL(BETA-1-4)XYL(BETA)-MU BY THE USE OF BETA-D-GALACTOSIDASE

The title trisaccharide-serine conjugate 1 constituting the linkage re gion between glycosaminoglycan and protein in proteoglycan, was synthe sized via a trisaccharide p-nitrophenyl (PNP) glycoside prepared by st epwise enzymatic transglycosidation to Xyl-PNP with a beta-D-galactosi dase. In the second transglycosidation step, partial protection of the disaccharide intermediate, Gal-Xyl-PNP, furnished selective galactosy lation at the 3'-position. Cleavage of the PNP group after peracetylat ion, chemical coupling with serine and final deprotection afforded 1. Fluorescence labeled trisaccharide, Gal(beta 1-3)Gal(beta 1-4)Xyl(beta )-MU (MU: 4-methylumbelliferyl) (2) was also synthesized in a similar way. Copyright (C) 1996 Elsevier Science Ltd