Recent progress in glycopeptide synthesis

Glycoproteins consist of carbohydrates covalently linked with proteins. They are widely distributed in nature both in animals and plants, and have also been discovered in some bacteria and viruses. Practically all cells produce glycoproteins and the ubiquitous occurrence of these glycoconjugates reflect their vital function in many physiological and pathological processes. Glycopeptides, which retain the critical carbohydrate-peptide linkage region of a glycoprotein but lack its size and complexity, are much more amenable to study and are important models for glycoproteins. The selective chemical synthesis of glycopeptides, either in solution or by solid phase procedure, and more recently enzymatic synthesis, has made remarkable progress over the last years. Strategies for generating glycopeptide mimics with non-native sugar-peptide linkages have been recently described which use chemoselective ligation, the selective covalent coupling of mutually and uniquely reactive functional groups under mild, aqueous conditions, without protecting groups or activation procedures.