PMID: 39598Oct 10, 1979

On the stoichiometry and thermodynamics of proton-pumping cytochrome c oxidase in mitochondria

Biochimica Et Biophysica Acta
K Krab, M Wikström

Abstract

Different approaches have been used to evaluate the stoichiometry of proton translocation linked to cytochrome c oxidase in rat liver mitochondria. A mathematical model was designed that successfully describes the kinetics of redox-linked proton translocation provided that the rate of electron transfer is not too high. With ascorbate as reductant, an essentially pH-independent (in the pH range 6--8.5) proton ejection stoichiometry (H+/e-) is obtained from either initial rates of H+ ejection (0.86 +/- 0.12), or the model (0.87 +/- 0.14). Similar results are obtained with either ferrocyanide, N.N.N',N'-tetramethyl-p-phenylenediamine or externally added cytochrome c mediating between ascorbate and cytochrome c in rotenone- and antimycin-inhibited mitochondria. Oxygen pulse experiments with ferrocytochrome c as substrate show fully uncoupler-sensitive redox-linked proton ejection with a stoichiometry of 0.78 +/- 0.14. With murexide to measure Ca2+ uptake during oxidation of ferrocyanide, we found a stoichiometry of two positive charges taken up/electron transferred, confirming earlier findings. These results provide strong evidence that cytochrome c oxidase functions as a redox-linked proton pump with a stoichiometry of one H+ ejec...Continue Reading

References

Apr 1, 1984·Journal of Bioenergetics and Biomembranes·J A Freedman, S H Chan
Dec 1, 1994·Journal of Bioenergetics and Biomembranes·J E MorganM Wikström
Sep 30, 1980·The Journal of Membrane Biology·M Klingenberg
Dec 1, 1982·Proceedings of the National Academy of Sciences of the United States of America·B ReynafarjeA L Lehninger
Feb 1, 1983·Biological Reviews of the Cambridge Philosophical Society·W W Wainio
Jun 6, 1988·FEBS Letters·P R RichP Mitchell
Jul 16, 2003·Archives of Biochemistry and Biophysics·A Jeannine LincolnL J Prochaska
Jan 14, 1983·Biochemical and Biophysical Research Communications·N S ReimerT E King
Jul 1, 1986·Archives of Biochemistry and Biophysics·T E Gunter, B D Jensen
Aug 11, 2007·Biochimica Et Biophysica Acta·M Wikström, Michael I Verkhovsky
Sep 14, 1981·Biochimica Et Biophysica Acta·L J ProchaskaG Buse

Citations

Nov 1, 1978·Proceedings of the National Academy of Sciences of the United States of America·A AlexandreA L Lehninger
Nov 17, 1977·Biochimica Et Biophysica Acta·M Wikström, H T Saari
Feb 9, 1978·Biochimica Et Biophysica Acta·G F AzzoneS Massari
Feb 1, 1976·Proceedings of the National Academy of Sciences of the United States of America·M D BrandA L Lehninger
Nov 5, 1974·Biochemistry·H Rottenberg, A Scarpa

Related Concepts

Thermodynamics
Cytochrome c Oxidase Subunit VIa
Rotenone
Mitochondria, Liver
COX1
Antimycin A1
Oxidation-Reduction
Hydrogen-Ion Concentration
Respiratory Chain
Metazoa

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