Proton translocation by the H+-ATPase of mitochondria. Effect of modification by monofunctional reagents of thiol residues in F0 polypeptides.
A study is presented on the effect of chemical modification of thiol groups on proton conduction by the H+-ATPase complex in 'inside out' submitochondrial particles, before and after removal of the F1 moiety, and by F0 liposomes. The results obtained show that modification with monofunctional reagents [N-ethylmaleimide, 2,2'-dithiobispyridine, mersalyl and N-(7-dimethylamino-4-methyl-coumarinyl)-maleimide] of thiol residues in membrane integral proteins of F0 results in inhibition of proton conduction. Comparison of the inhibitory effects with the binding of [14C]N-ethylmaleimide to the various F0 polypeptides indicates that the inhibition of proton conduction by thiol reagents was correlated with modification of the 25-kDa, 11-kDa and 9-kDa (N,N'-dicyclohexylcarbodiimide-binding protein) proteins. Involvement of the last component is supported by the observation that modification by thiol reagents depressed the binding of N,N'-dicyclo[14C]hexylcarbodiimide to the 9-kDa protein.
D000818:Animals; D002417:Cattle; D008081:Liposomes / Q000378:metabolism; D008929:Mitochondria, Heart / Q000201:enzymology*; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011522:Protons; D013439:Sulfhydryl Reagents / Q000378:metabolism / Q000494:pharmacology*
D008081:Liposomes; D011522:Protons; D013439:Sulfhydryl Reagents; D006180:Proton-Translocating ATPases