Table 1 A selection of important post-translational cysteine modifications which have been identified in mammalian proteins and enzymes

There is mounting evidence that most of these modifications occur inside the living cell, especially under conditions of OS. Owing to the extensive redox activity of sulfur, and its ability to occur in many different chemotypes in vivo, this list of modifications is neither complete nor final (for details and references, see the text. Pr, protein.

Post-translational cysteine modificationFormulaPossible function
S-glutathiolationPrSSGRegulation of protein function and enzyme activity
Protein disulfidePrSSPr'Regulation of function/activity, protein–protein interactions
S-nitrosationPrSNORegulation of function/activity
Sulfenic acidPrSOHCatalysis, redox switch
Sulfinic acidPrS(O)OH(Irreversible) redox switch
ThiosulfinatePrS(O)SPr'Intermediate in enzyme-based redox processes
Sulfinic phospho esterPrS(O)OPO32−Intermediate in enzyme-based redox processes