Conjugation of Human <i>N</i>‐Glycans Improves the Drug Properties of Existing Peptides and Proteins

Glycosylation is one of the most ubiquitous post-translational modifications observed in peptides and proteins. It affects the structural and functional characteristics of these macromolecules, thereby exerting a profound influence on a multitude of biological processes. N-Glycans are expected to be a beneficial modifier for increasing the solubility and in vivo half-life, and reducing the aggregation and immunogenicity of native bioactive peptides and proteins, which have seen limited clinical utility due to their short blood half-life and unsuitable physicochemical properties. Chemoselective glycosylation reactions that can be conducted post-synthesis and in aqueous conditions are a promising strategy for the high-throughput development of peptide/protein drugs. This "glycoconjugation" approach is particularly advantageous in that manipulation of glycan protecting groups is not necessary, thereby allowing conjugation reactions to be carried out between target molecules and unprotected glycans. By providing a single glycosylation profile, i. e., glycan structure, number, and position, glycoconjugation not only allows the beneficial properties of N-glycans to be exploited, but also facilitates the investigation of N-glycan function.