Fig. 1.

Endogenous scavenging of cellular peroxide. The cell’s steady-state peroxide (ROOH) levels are largely maintained by the activities of catalase, glutathione peroxidases (GPx) and the thioredoxin-assisted peroxidases (peroxiredoxins, Prx). This system also maintains cellular protein cysteines in a reduced (red) state. During oxidative stress, where cellular peroxides are elevated, there is an increased level of oxidized (ox) protein cysteines that leads to inactivation of phosphatases and transcription factors and dysregulated inflammatory reactions. This is the drug target and rationale for the development of catalase and GPx mimics.