Long-lived reactive species on free-radical-damaged proteins.

We have demonstrated two novel reactive species on radical-modified proteins which are relatively long-lived, one oxidizing and one reducing. The two species are reactive with critical biological components, and so may be of physiological and pathological importance. The oxidizing species, which have been identified as protein hydroperoxides, can consume key cellular reductants, such as ascorbate and glutathione. The reducing species can act on both free and metalloprotein forms of copper and iron ions, which participate in radical generation. These findings suggest that proteins may act as traps for the chemical energy released by free radicals, with the capacity to pass it on to other molecules. The long-lived nature of both the reactive moieties indicates that they may be able to diffuse and transfer damaging reactions to distant sites.