Chemoselective conjugation is achieved through redox reactivity by reacting an N-transfer oxidant with a thioether substrate in a redox reaction in an aqueous environment to form a conjugation product. In embodiments, Redox-Activated Chemical Tagging (ReACT) strategies for methionine-based protein functionalization. Oxaziridine (Ox) compounds serve as oxidant-mediated reagents for direct functionalization by converting methionine to the corresponding sulfimide conjugation product.

Chemoselective conjugation is achieved through redox reactivity by reacting an N-transfer oxidant with a thioether substrate in a redox reaction in an aqueous environment to form a conjugation product. In embodiments, Redox-Activated Chemical Tagging (ReACT) strategies for methionine-based protein functionalization. Oxaziridine (Ox) compounds serve as oxidant-mediated reagents for direct functionalization by converting methionine to the corresponding sulfimide conjugation product.

This disclosure relates to the field of protein preparation and mass spectrometry analysis. In some embodiments, the disclosure relates to compositions and methods for simplifying mass spectrometry analysis by reducing methionine oxidation of protein samples.