The K(+)-ionophores nonactin and valinomycin interact differently with the protein of reconstituted cytochrome c oxidase.
The K(+)-ionophores valinomycin and nonactin induce a qualitatively identical change of the visible spectrum of isolated oxidized cytochrome c oxidase (red shift), but the amplitude is half with nonactin. Valinomycin, in the presence or absence of a protonophore, stimulates the respiration of the reconstituted enzyme to a higher extent than nonactin and results in a higher Km for cytochrome c. In contrast, nonactin causes a fivefold rate of proton conductivity across a liposomal membrane, after induction of a K(+)-diffusion potential. The data indicate that respiratory control by these antibiotics is not only due to degradation of a membrane potential, but rather to specific interaction with and modification of cytochrome c oxidase.
Steverding
D
D
Fachbereich Chemie der Philipps-Universität, Marburg, Federal Republic of Germany.
Kadenbach
B
B
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D066298:In Vitro Techniques; D007476:Ionophores / Q000494:pharmacology*; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism; D018942:Macrolides; D010101:Oxygen Consumption / Q000187:drug effects; D011188:Potassium / Q000378:metabolism; D011522:Protons; D013053:Spectrophotometry; D014634:Valinomycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D007476:Ionophores; D008081:Liposomes; D018942:Macrolides; D011522:Protons; D014634:Valinomycin; D003576:Electron Transport Complex IV; D011188:Potassium; C050476:nonactin