A novel superoxide radical generator in heart mitochondria.
Experimental evidence is presented demonstrating the existence of a potent O2.- source in heart mitochondria. The novel O2.- generator is more active than any other known mitochondrial O2.- generator and also exhibits a higher affinity for molecular oxygen. In contrast to mitochondrial O2.- sources reported previously [(1974) FEBS Lett. 42, 68-72; (1978) Eur. J. Biochem. 82, 563-567], the O2.- generator described in this paper is not involved in energy-linked respiration. Superoxide radicals from this source require NADH to initiate their generation, and the radicals formed are released entirely into the extramitochondrial space. NADH-related O2.- generation was also observed with the solubilized exogenous NADH oxidoreductase of heart mitochondria, an enzyme recently described [(1987) Eur. J. Biochem., submitted]. This finding together with the lack of an NADH-dependent O2.- source in liver mitochondria suggests that the novel O2.- generator and the exogenous NADH oxidoreductase of heart mitochondria are identical.
D000818:Animals; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*
D009243:NAD; D013481:Superoxides; D013482:Superoxide Dismutase; D009247:NADH, NADPH Oxidoreductases