Vinyl thianthrenium-mediated cysteine bioconjugation

Covalent cysteine labeling is an important tool in protein modification, however, current methodologies suffer from limited reactivities and require the prior synthesis of individual derivative reagents. Now, a covalent cysteine labeling method that converts the cysteinyl thiol into episulfonium electrophiles in situ has been developed, enabling reactions with various nucleophiles in one step.