SYNTHETIC O-GLYCOPEPTIDES AS MODEL SUBSTRATES FOR GLYCOSYLTRANSFERASES

A new approach to O-glycopeptides of the glucosamine type is described. N-Urethane protected, peracetylated glucosamine is converted into its 1-thio (1-bromo) derivative and used for glycosylation of a variety of protected serine or threonine derivatives as acceptors. The urethane group is easily exchanged for the natural N-acetyl moiety and O-deacetylation is achieved with hydrazine/methanol. The resulting O-GlcNAc derivatives are subjected to an enzymatic galactosylation procedure using beta-1,4-galactosyluwsferase (EC 2.4.1.22) to furnish O-glycopeptides of the neolactosamine type.