A NEW METHOD FOR THE SYNTHESIS OF NEOGLYCOPEPTIDES

A new method for conjugation of small carbohydrates to peptides based on maleimido-thiol chemistry is described. The reducing carbohydrate i s reacted with S-trityl-2-mercaptoethylamine in methanol. The resultin g Schiff base is then stabilized by acetylation with acetic anhydride to give an S-trityl-protected glycosylamide. Activation of the carbohy drate is effected by brief treatment with trifluoroacetic acid/triisop ropylsilane, followed by precipitation in ether. The thiol-functionali zed carbohydrate is then reacted with a maleimido-modified peptide to give a neoglycopeptide. The potential of this method was investigated using maltose as the model compound. Furthermore, we prepared five mal eimido-modified model peptides. In contrast to some literature reports , we found that the maleimido group is stable to treatment trifluoroac etic acid/triisopropylsilane which was used to cleave the modified pep tides from the resin.