SYNTHETIC GLYCOSYLATION OF PEPTIDES USING UNPROTECTED SACCHARIDE BETA-GLYCOSYLAMINES

Glycopeptides can be valuable tools in determining the influence of ca rbohydrate moieties on the intrinsic properties of glycoproteins. Howe ver, glycopeptides of sufficient quantity and purity are as yet not re adily available from biological sources. The chemical coupling of a be ta-glycosylamino group of an unprotected carbohydrate with an activate d aspartic acid residue of an unprotected peptide is a simple method f or synthesizing asparagine-linked glycopeptides. In this report we dem onstrate that the use of this method is not restricted to beta-glycosy lamines of simple monosaccharides or short aspartic acid-containing pe ntapeptides. This is illustrated by the syntheses of several glycopent apeptides containing N,N'-diacetylchitobiose, a glutamine-linked glyco pentapeptide containing a biantennary complex oligosaccharide, and gly cosylated variants of two analogs of a polypeptide hormone, atriopepti n, containing N,N'-diacetylchitobiose.