17] Conjugation of glycopeptides to proteins

Abstract

This chapter focuses on the conjugation of glycopeptides to proteins. Proteins modified with carbohydrate derivatives have been valuable in studies of carbohydrate recognition. There are a number of simple glycosides that can be attached to proteins. To conjugate glycopeptides to proteins or other amino compounds, a heterobifunctional group has been used with some success. This chapter developed a heterobifunctional reagent with which coupling of a glycopeptide can be accomplished with ease and very high efficiency. The reagent contains an acyl hydrazide and an acetal. The acyl hydrazide is first converted to the corresponding acyl azide and conjugated to a glycopeptide. The acetal group is then hydrolyzed under mild conditions to unveil the aldehydo group. The aldehydo group is then used for the reductive alkylation of free amino groups in proteins. The heterobifunctional reagent can be used to couple glycopeptides to proteins or to other amino compounds with high efficiency.