CHAPTER 5: Chemical Synthesis and Engineering of N-Linked Glycoproteins

Understanding the function of protein glycosylation is an essential but thus far fairly rudimentary area of study, due to the incredible diversity of glycans that can be covalently attached to the peptide backbone. Access to homogeneous samples of glycoproteins is required to rigorously characterize glycan functions. Currently, chemical methods are a valid approach to obtain single glycoforms of a protein of interest. This chapter presents an overview of recent studies on the de novo synthesis of N-glycosylated proteins as homogeneous glycoforms, and focuses on examples where the glycosylation reactions, with both natural and unnatural linkages, were accomplished via chemical methods. Accordingly, the related key methodological developments and advances in this emerging field are highlighted. Furthermore, several examples of chemical biology studies using chemically synthesized homogeneous glycoproteins are briefly reviewed. The concluding section summarizes the accomplishments and current challenges in chemical synthesis of N-glycoproteins, and provides a brief outlook for future directions.