Thiols in cellular redox signalling and control.

Reactive oxygen (ROS) and reactive nitrogen species (RNS) produced in vivo at levels that cannot be dealt with adequately by endogenous antioxidant systems can lead to the damage of lipids, proteins, carbohydrates and nucleic acids. Oxidative modification of these molecules by toxic levels of ROS and RNS represents an extreme event that can lead to deleterious consequences such as loss of function. More recently, however, interest has focused on the formation of these species at sub-toxic levels and their potential to act as biological signal molecules.