Proteome screens for Cys residues oxidation: the redoxome.

The oxidation of the cysteine (Cys) residue to sulfenic (-S-OH), disulfide (-S-S-), or S-nitroso (S-NO) forms are thought to be a posttranslational modifications that regulate protein function. However, despite a few solid examples of its occurrence, thiol-redox regulation of protein function is still debated and often seen as an exotic phenomenon. A systematic and exhaustive characterization of all oxidized Cys residues, an experimental approach called redox proteomics or redoxome analysis, should help establish the physiological scope of Cys residue oxidation and give clues to its mechanisms. Redox proteomics still remains a technical challenge, mainly because of the labile nature of thiol-redox reactions and the lack of tools to directly detect the modified residues. Here we consider recent technical advances in redox proteomics, focusing on a gel-based fluorescent method and on the shotgun OxICAT technique.