Inhibition of plant and animal cytochrome oxidases by nitrous oxide as a function of cytochrome c concentration.
Cytochrome oxidase from both pea leaves and bovine heart shows lower activity under a mixture of 79% N2O/21% O2 than under ambient air. This inhibition is not detectable below 5 microM cytochrome c but appears with increasing concentrations of cytochrome c. These results suggest that the N2O-induced inhibition of cytochrome c oxidase is modulated by cytochrome c concentration. This seems to concern only the lowest affinity site of the oxidase. Apparently, N2O and cytochrome c do not share the same site of fixation on the oxidase.
Chervin
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Département de Physiologie Végétale et Ecosystèmes, Centre d'Etudes de Cadarache, Saint-Paul-lez-Durance, France.
Thibaud
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MC
D000818:Animals; D002417:Cattle; D003574:Cytochrome c Group / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007887:Fabaceae; D009206:Myocardium / Q000201:enzymology*; D009609:Nitrous Oxide / Q000494:pharmacology*; D017830:Octoxynol; D010944:Plants / Q000201:enzymology*; D010946:Plants, Medicinal; D011092:Polyethylene Glycols
D003574:Cytochrome c Group; D011092:Polyethylene Glycols; D017830:Octoxynol; D003576:Electron Transport Complex IV; D009609:Nitrous Oxide