Synthesis of glycopeptides with the TN and T antigen structures, and their coupling to bovine serum albumin.

Glycopeptides with TN and T antigen structures that represent the N-terminal tripeptide of asialoglycophorin with blood-group M specificity have been synthesized using fluorenylmethoxycarbonyl (Fmoc) and 2-pyridylethoxycarbonyl (Pyoc) groups for amino protection and the benzyl ester as the carboxyl-blocking function. The Fmoc and the Pyoc groups could be removed by treatment with the weak base morpholine under conditions where the base-sensitive O-glycosyl-serine and -threonine linkages were stable. Ester groups were removed from the carbohydrate moieties with methanolic hydrazine, to give the TN and T antigen glycopeptides which were coupled to bovine serum albumin (BSA) via a carbodi-imide procedure and without any spacer groups. The resulting conjugates contained an average of greater than 20 glycopeptides per protein molecule. They are not microheterogeneous in the carbohydrate part as is commonly found for glycoproteins isolated from biological sources.