Variable proton conductance of submitochondrial particles

The relationship between the rate of substrate oxidation and the protonmotive force (electrochemical proton gradient) generated by bovine heart submitochondrial particles has been examined. Unexpectedly, oxidation of succinate generated a higher protonmotive force than the oxidation of NADH, althoug...

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Bibliographic Details
Published in:Biochemistry (Easton) 1979-12, Vol.18 (25), p.5737-5742
Main Authors: Sorgato, M. Catia, Ferguson, Stuart J
Format: Article
Language:English
Subjects:
Animals
Cattle
Hydrogen-Ion Concentration
Kinetics
Mitochondria - metabolism
Mitochondria, Heart - drug effects
Mitochondria, Heart - metabolism
NAD - metabolism
Oxidation-Reduction
Rotenone - pharmacology
Submitochondrial Particles - drug effects
Submitochondrial Particles - metabolism
Succinates - metabolism
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Summary:The relationship between the rate of substrate oxidation and the protonmotive force (electrochemical proton gradient) generated by bovine heart submitochondrial particles has been examined. Unexpectedly, oxidation of succinate generated a higher protonmotive force than the oxidation of NADH, although the rate of proton translocation across the membrane was inferred to be considerably lower with succinate as substrate. The data suggest that the flow of electrons through site 1 of the respiratory chain may increase the conductance of the mitochondrial membrane for protons. Upon reduction of the rate of succinate oxidation by titration with malonate, the protonmotive force remained essentially constant until the extent of inhibition was greater than 75%. The general conclusion from this work is that a constant passive membrane conductance for protons cannot be assumed.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00592a034