Current strategies for in vitro protein glycosylation

Natural glycoproteins are mixtures of multiple glycoforms possessing identical peptide backbones, but differing in composition of glycan parts. This microheterogeneity presents a serious challenge in pharmaceutical applications of glycoproteins, where well-characterized and reproducible structural characteristics are required. Due to the growing importance of biopharmaceutical glycoconjugates, a wide variety of practical approaches to the preparation of glycosylated proteins and oligopeptides have been developed in recent years, with emphasis on strategies for selective glycosylation. This review presents a concise summary of concepts and synthetic approaches currently employed in glycoprotein chemistry.