[Role of superoxide anion-radicals and superoxide dismutase in the lipid photoperoxidation reactions of isolated chloroplasts].

Exogenous superoxide dismutase (SOD, erythrocuprein) inhibits the chlorophyll bleaching and photoperoxidation of polyunsaturated lipids in pea isolated chloroplasts. As SOD did not produce this effect in tris-HCl buffer, it is suggested that peroxidation is mediated by the OH radicals which may appear in illuminated chloroplasts with the participation of superoxide radicals and hydrogen peroxide. The physiological role of SOD is discussed in relation to the stability of cells photosynthesizing organisms towards light and oxygen effect.