title: Studies on the effects of copper deficiency on rat liver mitochondria. II. Effects on oxidative phosphorylation.
abstract: Effects of dietary copper deficiency in rats on respiratory enzymes of isolated rat liver mitochondria have been studied. After 2 weeks of Cu-depletion, cytochrome c oxidase (EC 1.9.3.1) activity had declined by 42% and between 4 and 8 weeks exhibited between 20 and 25% of the activity of control mitochondria. Activities of NADH cytochrome c reductase (EC 1.6.99.3) and succinate cytochrome c reductase (EC 1.3.99.1), were unaffected initially but declined by 32 and 46%, respectively, after 8 weeks of Cu-depletion. After 4 weeks there was a significant (34%) decline in succinate supported state 3 respiration with only a modest (18%) decline in state 4 respiration. The ADP:O ratio was unaffected by Cu-depletion after 6 and 8 weeks of dietary Cu-restriction. State 3 respiration was significantly reduced after 6 weeks when glutamate/malate or beta-hydroxybutyrate were used as substrates, whereas state 4 respiration and ADP:O ratios were unaffected. The fall in state 3 respiration was of sufficient magnitude at 8 weeks to cause a significant decline in the respiratory control ratio with all substrates. Comparisons between the relative activities of cytochrome c oxidase and reductase activities in Cu-deficient preparations, the relatively specific effect of the deficiency on state 3 respiration with all substrates tested and the ability to increase significantly oxygen consumption in excess of maximal state 3 respiration by the uncoupler 2,4-dinitrophenol suggest that the defect in Cu-deficient mitochondria cannot be attributed solely to the decreased activity of cytochrome c oxidase.
authors.forename: N T
authors.initials: NT
authors.lastname: Davies
authors.forename: C B
authors.initials: CB
authors.lastname: Lawrence
authors.forename: C F
authors.initials: CF
authors.lastname: Mills
mesh_terms: D020155:3-Hydroxybutyric Acid; D000818:Animals; D003300:Copper / Q000172:deficiency*; D003576:Electron Transport Complex IV / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D006885:Hydroxybutyrates / Q000378:metabolism; D008293:Malates / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D051381:Rats; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid
chemical_list: D005971:Glutamates; D006885:Hydroxybutyrates; D008293:Malates; D013386:Succinates; D018698:Glutamic Acid; D003300:Copper; C030298:malic acid; D019802:Succinic Acid; D013384:Succinate Cytochrome c Oxidoreductase; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D020155:3-Hydroxybutyric Acid