title: Generation of superoxide anion by the NADH dehydrogenase of bovine heart mitochondria.
abstract: Submitochondrial particles from bovine heart in which NADH dehydrogenase is reduced by either addition of NADH and rotenone or by reversed electron transfer generate 0.9 +/- 0.1 nmol of O2-/min per mg of protein at pH 7.4 and at 30 degrees C. When NADH is used as substrate, rotenone, antimycin and cyanide increase O2- production. In NADH- and antimycin-supplemented submitochondrial particles, rotenone has a biphasic effect: it increases O2- production at the NADH dehydrogenase and it inhibits O2- production at the ubiquinone-cytochrome b site. The generation of O2- by the rotenone, the uncoupler carbonyl cyanide rho-trifluoromethoxyphenylhydrazone and oligomycin at concentrations similar to those required to inhibit energy-dependent succinate-NAD reductase. Cyanide did not affect O2- generation at the NADH dehydrogenase, but inhibited O2- production at the ubiquinone-cytochrome b site. Production of O2- at the NADH dehydrogenase is about 50% of the O2- generation but the ubiquinone-cytochrome b area at pH 7.4. Additivity of the two mitochondrial sites of O2- generation was observed over the pH range from 7.0 to 8.8. AN O2- -dependent autocatalytic process that requires NADH, submitochondrial particles and adrenaline is described.
mesh_terms: D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002417:Cattle; D003486:Cyanides / Q000494:pharmacology; D003579:Cytochrome Reductases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008929:Mitochondria, Heart / Q000201:enzymology*; D009245:NADH Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D013367:Submitochondrial Particles / Q000201:enzymology; D013481:Superoxides / Q000378:metabolism*
chemical_list: D003486:Cyanides; D012402:Rotenone; D013481:Superoxides; D000968:Antimycin A; D003579:Cytochrome Reductases; D009245:NADH Dehydrogenase; D010100:Oxygen