Recent Advances in Chemical Protein Modification via Cysteine

Proteins are the most abundant biomolecules in nature and are involved almost in all living processes. Chemical modification of proteins is an efficient strategy to mediate and study the physical and chemical properties and biological functionalities of proteins. Most protein chemical modifications are based on the bioorthogonal reactivities of the side chain functional groups of certain amino acid residues. Among 20 proteinogenic amino acids, cysteine has become the best choice for chemical protein modification, owning to its relative low abundance in proteins, the unique nucleophilicity and low redox potential of its mercaptan group. The recent advances in chemical protein modification via cysteine are comprehensively reviewed and the challenges and applications for future development are discussed.