Energy conservation by the plant mitochondrial cyanide-insensitive oxidase. Some additional evidence.
Several measures of energy conservation, namely ADP/O ratio, P/O ratio, ATP/O ratio and phosphorylation detected by continuous assay with purified firefly luciferase and luciferin, all show phosphorylation can occur with mung-bean mitochondria at cyanide concentrations sufficient to inhibit the cytochrome oxidase system. Phosphorylation in the presence of cyanide is uncoupler- oligomycin- and salicylhydroxamate-sensitive. The participation of phosphorylation site 1 is excluded, phosphorylation being attributable to a single phosphorylation site associated with the cyanide-insensitive oxidase. The cyanide-insensitive oxidase has also been shown to support a variety of other energy-linked functions, namely, Ca2+ uptake, reversed electron transport and the maintenance of a membrane potential detected by the dye probes 8-anilinonaphthalene-1-sulphonate and safranine. High concentrations of cyanide have uncoupler-like activity, decreasing the ADP/O ratio and the t 1/2 for the decay of a pH pulse through the the mitochondrial membrane. This uncoupler-like effect is most marked with aged mitochondria. The observations of energy conservation attributable to the cyanide-insensitive oxidase are compared with other reports where it is concluded that the alternative oxidase is uncoupled.
D000255:Adenosine Triphosphate / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003486:Cyanides / Q000494:pharmacology; D004579:Electron Transport; D004734:Energy Metabolism / Q000187:drug effects; D007887:Fabaceae / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010088:Oxidoreductases / Q000378:metabolism*; D010944:Plants / Q000187:drug effects / Q000201:enzymology*; D010946:Plants, Medicinal
D003486:Cyanides; D000255:Adenosine Triphosphate; D010088:Oxidoreductases