Figure 1
From: SVM-SulfoSite: A support vector machine based predictor for sulfenylation sites
In the presence of an oxidizing agent (ROOH), the thiolate anion of a redox-sensitive Cys (Cys-S−) is reversibly oxidized to form a sulfenic acid (SOH). When in close proximity to another reactive Cys (SH), either in the same protein molecule or in another protein, SOH leads to disulfide bond (S-S) formation. In addition to Cys residues in proteins, SOH can also react with the cellular antioxidant, glutathione (g-Glu-Cys-Gly; GSH) to form a mixed S-S bond (PSSG). Aside from altering the chemical properties of the Cys residue and the tertiary structure of the protein, S-S bonds are also believed to prevent terminal oxidation to sulfinic (SO2H) and sulfonic (SO3H) acid. Disulfide bonds can be reduced back to the thiol by cellular antioxidant enzymes, such as glutaredoxin (Grx) or thioredoxin (Trx).
