[Biochemistry of thiol groups: the role of glutathione].

Glutathione (GSH) comprises the bulk of the pool of free thiol groups in biological systems. Since its first description as philothione 100 years ago, there have been repeated surprises in discoveries of novel functions. Just recently the important role of thioethers with products of the lipoxygenase reaction, i.e., the leukotrienes, was revealed as mediator of physiological and pathophysiological processes. Another major function resides in detoxication, GSH being cosubstrate in the GSH-peroxidase reaction for the reduction of hydroperoxides in the defense against oxidative stress. Interest also focuses on reactions of glutathionyl radicals in protection by thiols against DNA damage resulting from ionizing radiation.