Chemical Synthesis and Biological Applications of O‐GlcNAcylated Peptides and Proteins

Abstract All human cells use O ‐GlcNAc protein modifications ( O ‐linked N ‐acetylglucosamine) to rapidly adapt to changing nutrient and stress conditions through signaling, epigenetic, and proteostasis mechanisms. A key challenge for biologists in defining precise roles for specific O ‐GlcNAc sites is synthetic access to homogenous isoforms of O ‐GlcNAc proteins, a result of the non‐genetically templated, transient, and heterogeneous nature of O ‐GlcNAc modifications. Toward a solution, this review details the state of the art of two strategies for O ‐GlcNAc protein modification: advances in “bottom‐up” O ‐GlcNAc peptide synthesis and direct “top‐down” installation of O ‐GlcNAc on full proteins. We also describe key applications of synthetic O ‐GlcNAc peptide and protein tools as therapeutics, biophysical structure–function studies, biomarkers, and as disease mechanistic probes to advance translational O ‐GlcNAc biology.