The respiratory chain of Paramecium tetraurelia in wild type and the mutant Cl1. II. Cyanide-insensitive respiration. Function and regulation.
1. The cyanide-insensitive respiration in Paramecium tetraurelia was found to be located in mitochondria. 2. Sensitivity of the mitochondrial respiration to cyanide depended on growth conditions. Under standard conditions of growth, 15--20% of respiration was insensitive to 1 mM cyanide. Full resistance to 1 mM cyanide was observed by growing cells in the presence of erythromycin (100--400 microgram/ml) 0.2 mM cyanide. The mitochondrial respiration of the mutant Cl1 harvested during the exponential phase of growth was largely insensitive to cyanide (more than 80%). 3. Pyruvate was oxidized at the same rate by wild type mitochondria and mitochondria of the mutant Cl1. In contrast, succinate oxidation was 2--3 times faster in mitochondria of the mutant Cl1 than in wild type mitochondria. 4. The cyanide-insensitive respiration was inhibited by 1 mM salicylhydroxamic acid to nearly 100%. Other efficient respiratory inhibitors included amytal and heptylhydroxyquinoline. Antimycin was not inhibitory even at concentrations as high as 5 microgram/mg protein, a finding consistent with the lack of antimycin binding sites.
D000818:Animals; D001692:Biological Transport; D003486:Cyanides / Q000494:pharmacology*; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009154:Mutation; D010101:Oxygen Consumption / Q000187:drug effects; D010247:Paramecium / Q000187:drug effects / Q000378:metabolism*; D013045:Species Specificity
D003486:Cyanides