Coupling of charge and proton movement in cytochrome c oxidase

Rich, Peter R.; Meunier, Brigitte; Mitchell, Roy; Moody, A. John

doi:10.1016/0005-2728(96)00055-2

Cited by 61 publications

(49 citation statements)

References 38 publications

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“…Mechanism (i) has the distinct advantage of maintaining the electroneutrality of the hydrophobic oxygen-reduction site as adding or removing a charge into this centre is thermodynamically unliwoured [8,27]. The ease at which a proton could leave the binuclear centre would then control the rate of electron transfer to haem a and CuA.…”

Section: Discussionmentioning

confidence: 99%

Nitric oxide ejects electrons from the binuclear centre of cytochrome c oxidase by reacting with oxidised copper: a general mechanism for the interaction of copper proteins with nitric oxide?

et al. 1997

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Small increases in NO concentration can inhibit mitochondrial oxygen consumption by reacting at the binuclear haem aa/CUB oxygen reduction site of cytochrome c oxidase. Here we demonstrate that under normal turnover conditions NO reacts initially with the oxidised CuB rather than the haem aa. We propose that hydration of an initial Cu+/NO + complex forms nitrite, a proton and CUB+; the latter ejects an electron from the binuclear centre and results in the observed (100 s q) reduction of other electron transfer centres in the enzyme (haem a and CUA). These reactions may have implications for the interactions of NO with other copper proteins.

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Section: Discussionmentioning

confidence: 99%

Nitric oxide ejects electrons from the binuclear centre of cytochrome c oxidase by reacting with oxidised copper: a general mechanism for the interaction of copper proteins with nitric oxide?

et al. 1997

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“…The relative concentrations of cytochrome bo in the various membrane preparations used were obtained from the CO-binding spectra of the fully reduced membranes because CO still binds with high affinity to kCu cyt.bo (K d 7 µM [10]). The relative proportions of kCu cyt.bo and jCu cyt.bo in a given preparation were obtained from the cyanide-binding spectra of the fully reduced membranes.…”

Section: Formatementioning

confidence: 99%

“…The relative proportions of kCu cyt.bo and jCu cyt.bo in a given preparation were obtained from the cyanide-binding spectra of the fully reduced membranes. Because cyanide (at 20 mM) does not bind to fully reduced kCu cyt.bo [10,15], the fraction of binding observed with the kCu membranes, when compared with that shown by jCu membranes, was taken as a direct indication of the fraction of jCu cyt.bo. Table 1 shows a summary of the measurements and calculations used to determine both the relative cytochrome bo concentrations and the level of copper deficiency of the membrane preparations.…”

Section: Formatementioning

confidence: 99%

“…Something similar is certainly possible for E. coli cytochrome bo, but although further kinetic information, at least for azide, could be obtained by using stopped flow, the major limitation in extending the pH range for any ligand is the increasing instability of the enzyme at extreme pH. It should be noted, however, despite the limitations of the data, that there is a clear contrast between the behaviour of cytochrome bo (and also of cytochrome c peroxidase) and that of metmyoglobin, for example, where the binding of anionic ligands does not require the co-binding of a proton [38] (for further discussion see [10]). …”

Section: Ligand Binding By Jcu Cytochrome Bomentioning

confidence: 99%

“…This led to the proposal that charge compensation by protonation was a general requirement in the reactions of the haem\Cu oxidases [8], and to a discussion of possible protonmotive mechanisms based on electrostatic principles [9][10][11]. These notions prompted us to extend our measurements to E. coli cytochrome bo to probe further the electroneutrality requirement of binuclear centre reactions and to begin to identify both the protonation sites and the access route or routes of protons to these sites.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the ligand-binding properties of native and copper-less cytochromes bo from Escherichia coli

Moody

Mitchell

Jeal

et al. 1997

Biochemical Journal

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The binding of four anionic ligands, cyanide, fluoride, azide and formate, to cytochrome bo purified from Escherichia coli cells grown with a copper supplement (+Cu cyt.bo) is described. Membrane-bound cytochrome bo that lacks the copper component, CuB, of its active site can be prepared from cells grown under conditions where the availability of copper is limited by the presence of a CuI chelator, 2,2′-bicinchinonic acid. The ligand-binding properties of this copper-less enzyme (-Cu cyt.bo) are compared with those of +Cu cyt.bo. As judged from near-UV/visible spectroscopic changes, cyanide forms a low-spin complex with +Cu cyt.bo, whereas azide, fluoride and formate form high-spin complexes. The pH-dependences of binding suggest that for all four of these anionic ligands, both the rates of binding and the binding affinities are primarily dependent on the concentration of their protonated forms. -Cu cyt.bo, which shows less than 15% of the duroquinol oxidase activity of +Cu cyt.bo, binds cyanide, azide and fluoride, but with greatly decreased affinity (< 1/30, 1/2000 and 1/2500 respectively at pH 5.5 compared with +Cu cyt.bo). The complex of azide with -Cu cyt.bo still seems to be high-spin and azide binding to -Cu cyt.bo is still pH-dependent, although less so than azide binding to +Cu cyt.bo.

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Cytochrome c Oxidase

Wikström

2010

Encyclopedia of Life Sciences

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Cytochrome c oxidase is the key enzyme of cell respiration in all eukaryotes and many prokaryotes. The cytochrome c oxidases belong to the haem–copper superfamily of structurally and functionally related enzymes; though related in structure, some bacterial variants lack amino acid residues that are known to be obligatory for the function of the members of the main family. All haem–copper oxidases have a unique bimetallic active site catalysing reduction of dioxygen (O 2 ) to water and an adjacent second haem group that donates electrons to this site. Here, the mechanism of O 2 reduction is reviewed. The membrane‐bound enzyme couples this reaction to translocation of protons across the membrane, and thus functions as a primary energy transducer that contributes to the formation of ATP (adenosine triphosphate) in aerobic life. The most recent knowledge of the function of this ‘proton pump’ is discussed. It is concluded that cytochrome c oxidase is an electrostatic energy‐transducing machine with high efficiency. Key Concepts: Cytochrome c oxidase is an electrostatically coupled energy transducer. The high affinity for O 2 is due to kinetic ligand trapping. O 2 reduction in cell respiration yields no reactive oxygen species.

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Coupling of charge and proton movement in cytochrome c oxidase

Cited by 61 publications

References 38 publications

Nitric oxide ejects electrons from the binuclear centre of cytochrome c oxidase by reacting with oxidised copper: a general mechanism for the interaction of copper proteins with nitric oxide?

Nitric oxide ejects electrons from the binuclear centre of cytochrome c oxidase by reacting with oxidised copper: a general mechanism for the interaction of copper proteins with nitric oxide?

Comparison of the ligand-binding properties of native and copper-less cytochromes bo from Escherichia coli

Cytochrome c Oxidase

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