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. 1991 Aug 15;88(16):7281–7283. doi: 10.1073/pnas.88.16.7281

Conformational switching at cytochrome a during steady-state turnover of cytochrome c oxidase.

R A Copeland 1
PMCID: PMC52278  PMID: 1651500

Abstract

As an electron transfer-driven proton pump, cytochrome c oxidase (ferrocytochrome-c:oxygen oxidoreductase, EC 1.9.3.1) must alternate between two conformations in each valence state of the redox element associated with ion translocation. Using second derivative absorption spectroscopy, the conformation of the cytochrome a cofactor has been investigated during steady-state turnover of this enzyme. Resting cytochrome c oxidase displays a transition for ferric cytochrome a at 430 nm. During aerobic steady-state turnover, this band is replaced by a ferrous cytochrome a transition at 450 nm. When anaerobicity is achieved, the transition occurs at 444 nm. The 450-nm-absorbing species is thus the dominant form during turnover, suggesting that conformational transitions of cytochrome a direct electron transfer during catalysis and may direct as well proton translocation in the last step of the respiratory electron transfer chain.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Babcock G. T., Callahan P. M. Redox-linked hydrogen bond strength changes in cytochrome a: implications for a cytochrome oxidase proton pump. Biochemistry. 1983 May 10;22(10):2314–2319. doi: 10.1021/bi00279a002. [DOI] [PubMed] [Google Scholar]
  2. Blair D. F., Bocian D. F., Babcock G. T., Chan S. I. Evidence for modulation of the heme absorptions of cytochrome c oxidase by metal-metal interactions. Biochemistry. 1982 Dec 21;21(26):6928–6935. doi: 10.1021/bi00269a048. [DOI] [PubMed] [Google Scholar]
  3. Brautigan D. L., Ferguson-Miller S., Margoliash E. Mitochondrial cytochrome c: preparation and activity of native and chemically modified cytochromes c. Methods Enzymol. 1978;53:128–164. doi: 10.1016/s0076-6879(78)53021-8. [DOI] [PubMed] [Google Scholar]
  4. Copeland R. A., Chan S. I. Proton translocation in proteins. Annu Rev Phys Chem. 1989;40:671–698. doi: 10.1146/annurev.pc.40.100189.003323. [DOI] [PubMed] [Google Scholar]
  5. Gelles J., Blair D. F., Chan S. I. The proton-pumping site of cytochrome c oxidase: a model of its structure and mechanism. Biochim Biophys Acta. 1986;853(3-4):205–236. doi: 10.1016/0304-4173(87)90002-4. [DOI] [PubMed] [Google Scholar]
  6. Hartzell C. R., Beinert H. Components of cytochrome c oxidase detectable by EPR spectroscopy. Biochim Biophys Acta. 1974 Dec 19;368(3):318–338. doi: 10.1016/0005-2728(74)90178-9. [DOI] [PubMed] [Google Scholar]
  7. Malmström B. G. Cytochrome oxidase: some unsolved problems and controversial issues. Arch Biochem Biophys. 1990 Aug 1;280(2):233–241. doi: 10.1016/0003-9861(90)90325-s. [DOI] [PubMed] [Google Scholar]
  8. Morgan J. E., Wikström M. Steady-state redox behavior of cytochrome c, cytochrome a, and CuA of cytochrome c oxidase in intact rat liver mitochondria. Biochemistry. 1991 Jan 29;30(4):948–958. doi: 10.1021/bi00218a010. [DOI] [PubMed] [Google Scholar]
  9. Nicholls P. Control of proteoliposomal cytochrome c oxidase: the partial reactions. Biochem Cell Biol. 1990 Sep;68(9):1135–1141. doi: 10.1139/o90-169. [DOI] [PubMed] [Google Scholar]
  10. Sherman D., Kotake S., Ishibe N., Copeland R. A. Resolution of the electronic transitions of cytochrome c oxidase: evidence for two conformational states of ferrous cytochrome alpha. Proc Natl Acad Sci U S A. 1991 May 15;88(10):4265–4269. doi: 10.1073/pnas.88.10.4265. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Wikström M. Identification of the electron transfers in cytochrome oxidase that are coupled to proton-pumping. Nature. 1989 Apr 27;338(6218):776–778. doi: 10.1038/338776a0. [DOI] [PubMed] [Google Scholar]
  12. YONETANI T. Studies on cytochrome oxidase. II. Steady state properties. J Biol Chem. 1960 Nov;235:3138–3143. [PubMed] [Google Scholar]

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