Thiol–Disulfide Balance: From the Concept of Oxidative Stress to that of Redox Regulation

Originally, small thiols, including glutathione, were viewed as protective antioxidants, acting as free radical scavengers in the context of oxidative damage. Recently, there is a growing literature showing that protein glutathionylation (formation of protein-glutathione mixed disulfides) and other forms of cysteine oxidation may be a means of redox regulation under physiological conditions. This review discusses the importance of protein oxidation in redox regulation in view of the recent data originating from the application of redox proteomics to identify redox-sensitive targets.