Participation of oxygen-free radicals in the oxido-reduction of proteins.

Recent studies have focused attention on the possible role of active oxygen species on protein damage and degradation. The reactions of free radicals on biomolecules are important in physiology and pathology. A number of systems that generate free radicals catalyze the oxidative modification of proteins in two species: protein peroxides, which can consume important antioxidants; and protein-bound reducing moieties, which can reduce transition metals, and may enhance their activity in radical reactions. Protein oxidation also contributes to the pool of damaged enzymes and accumulation of abnormal and damaged proteins, which increases during aging and in various pathological states, such as atherosclerosis, cancer, etc.