The electron distribution in the “activated” state of cytochrome c oxidase

Abstract Cytochrome c oxidase catalyzes reduction of O2 to H2O at a catalytic site that is composed of a copper ion and heme group. The reaction is linked to translocation of four protons across the membrane for each O2 reduced to water. The free energy associated with electron transfer to the catal...

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Autores principales:	Jóhanna Vilhjálmsdóttir, Robert B. Gennis, Peter Brzezinski
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2018
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/d67e73370d034262a14134e85ff95219
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spelling	oai:doaj.org-article:d67e73370d034262a14134e85ff952192021-12-02T11:41:03ZThe electron distribution in the “activated” state of cytochrome c oxidase10.1038/s41598-018-25779-w2045-2322https://doaj.org/article/d67e73370d034262a14134e85ff952192018-05-01T00:00:00Zhttps://doi.org/10.1038/s41598-018-25779-whttps://doaj.org/toc/2045-2322Abstract Cytochrome c oxidase catalyzes reduction of O2 to H2O at a catalytic site that is composed of a copper ion and heme group. The reaction is linked to translocation of four protons across the membrane for each O2 reduced to water. The free energy associated with electron transfer to the catalytic site is unequal for the four electron-transfer events. Most notably, the free energy associated with reduction of the catalytic site in the oxidized cytochrome c oxidase (state O) is not sufficient for proton pumping across the energized membrane. Yet, this electron transfer is mechanistically linked to proton pumping. To resolve this apparent discrepancy, a high-energy oxidized state (denoted O H ) was postulated and suggested to be populated only during catalytic turnover. The difference between states O and O H was suggested to be manifested in an elevated midpoint potential of CuB in the latter. This proposal predicts that one-electron reduction of cytochrome c oxidase after its oxidation would yield re-reduction of essentially only CuB. Here, we investigated this process and found ~5% and ~6% reduction of heme a 3 and CuB, respectively, i.e. the apparent redox potentials for heme a 3 and CuB are lower than that of heme a.Jóhanna VilhjálmsdóttirRobert B. GennisPeter BrzezinskiNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 8, Iss 1, Pp 1-11 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Jóhanna Vilhjálmsdóttir Robert B. Gennis Peter Brzezinski The electron distribution in the “activated” state of cytochrome c oxidase
description	Abstract Cytochrome c oxidase catalyzes reduction of O2 to H2O at a catalytic site that is composed of a copper ion and heme group. The reaction is linked to translocation of four protons across the membrane for each O2 reduced to water. The free energy associated with electron transfer to the catalytic site is unequal for the four electron-transfer events. Most notably, the free energy associated with reduction of the catalytic site in the oxidized cytochrome c oxidase (state O) is not sufficient for proton pumping across the energized membrane. Yet, this electron transfer is mechanistically linked to proton pumping. To resolve this apparent discrepancy, a high-energy oxidized state (denoted O H ) was postulated and suggested to be populated only during catalytic turnover. The difference between states O and O H was suggested to be manifested in an elevated midpoint potential of CuB in the latter. This proposal predicts that one-electron reduction of cytochrome c oxidase after its oxidation would yield re-reduction of essentially only CuB. Here, we investigated this process and found ~5% and ~6% reduction of heme a 3 and CuB, respectively, i.e. the apparent redox potentials for heme a 3 and CuB are lower than that of heme a.
format	article
author	Jóhanna Vilhjálmsdóttir Robert B. Gennis Peter Brzezinski
author_facet	Jóhanna Vilhjálmsdóttir Robert B. Gennis Peter Brzezinski
author_sort	Jóhanna Vilhjálmsdóttir
title	The electron distribution in the “activated” state of cytochrome c oxidase
title_short	The electron distribution in the “activated” state of cytochrome c oxidase
title_full	The electron distribution in the “activated” state of cytochrome c oxidase
title_fullStr	The electron distribution in the “activated” state of cytochrome c oxidase
title_full_unstemmed	The electron distribution in the “activated” state of cytochrome c oxidase
title_sort	electron distribution in the “activated” state of cytochrome c oxidase
publisher	Nature Portfolio
publishDate	2018
url	https://doaj.org/article/d67e73370d034262a14134e85ff95219
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The electron distribution in the “activated” state of cytochrome c oxidase

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