Studies on the mechanism of action of triphenyltin on proton conduction by the H+-ATPase of mitochondria.
A study is presented of the action of triphenyltin on the kinetics of the anaerobic relaxation of the proton gradient set up by respiration in various type of 'inside-out' inner membrane vesicles obtained by exposure of beef-heart mitochondria to ultrasonic energy. Triphenyltin is shown to act as a powerful inhibitor of the proton conductivity of the H+-ATPase. The inhibition persists after removal of the ATPase protein inhibitor, F1 and the oligomycin-sensitivity conferral protein (OSCP) from the particles. The inhibitory effect of triphenyltin is exerted, as in the case of oligomycin and N,N'-dicyclohexylcarbodiimide, on the F0 moiety of the ATPase complex. Comparison of the characteristics of the effect of triphenyltin on proton translocation in chloride and nitrate media shows that the inhibition of passive proton conductivity studied here is unrelated to the hydroxide/anion exchange induced by the organotin. Lack of additivity of the inhibition of H+ conduction by triphenyltin with that exerted by oligomycin and N,N'-dicyclohexylcarbodiimide and the kinetic pattern of the effect of triphenyltin show that the mechanism of action of the organotin is different from that of the other two inhibitors. The relevance of the results obtained with respect to the subunit location and chemical nature of the reaction site of triphenyltin in the H+-ATPase complex is discussed.
D000251:Adenosine Triphosphatases / Q000502:physiology*; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D006859:Hydrogen; D066298:In Vitro Techniques; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D009947:Organotin Compounds / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D006180:Proton-Translocating ATPases; D011522:Protons; D014465:Ultrasonics
D009947:Organotin Compounds; D011522:Protons; D006859:Hydrogen; C030665:triphenyltin; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases