Pro- and anti-oxidant activities of the mitochondrial respiratory chain: factors influencing NAD(P)H-induced lipid peroxidation

摘要: This paper is a study of factors influencing the rate lipid peroxidation in beef heart submitochondrial particles induced by NAD(P)H via NADH-ubiquinone oxidoreductase (Complex I) respiratory chain. In accordance with earlier observations, both NADH and NADPH initiated presence ADP-Fe3+. The reaction, measured as oxygen consumption formation thiobarbituric acid reactive substances, was biphasic function concentration, reaching maximum at low concentrations then declining. contrast, NADPH-initiated showed monophasic concentration profile hyperbolic character. Rotenone did not eliminate biphasicity NADH-induced indicating that this due to an antioxidant effect reduced ubiquinone high concentrations. conclusion further supported demonstration extraction from relieve inhibition However rhein, another inhibitor Complex I, eliminated biphasicity, even caused substantial stimulation upon pentane. No similar occurred case NADPH-induced peroxidation. Furthermore, rhein facilitated NADH- absence added ADP-Fe3+, fashion reported succinate theonyltrifluoroacetone. Based on these findings measurements redox states cytochromes KCN or NADPH, it concluded I may distinguish between electron input differences site(s) substrate binding pathways rates oxidation.