The location of Cu<sub>A</sub> in mammalian cytochrome <i>c</i> oxidase

Rich, Peter R.; West, Ian; Mitchell, Peter

doi:10.1016/0014-5793(88)81349-8

Cited by 58 publications

(34 citation statements)

References 25 publications

(35 reference statements)

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“…For example, electroneutrality principle, which is at work in our model, was suggested earlier by Rich et al [36]; the suggestion of a rapid proton delivery to form a metastable state is similar to Michel's model [19], and the protonation of His291 is also part of the various histidine cycle models [16], previously proposed by Wikstrom albeit in a very different context. The described combination of these elements, however, and the support of the electrostatic calculations are certainly new and represent a new self-consistent model worthwhile of experimental verification.…”

Section: ''Psupporting

confidence: 65%

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

POPOVI

2004

FEBS Letters

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Using electrostatic calculations, we have examined the dependence of the protonation state of cytochrome c oxidase from bovine heart on its redox state. Based on these calculations, we propose a possible scheme of redox-linked proton pumping. The scheme involves His291 -one of the ligands of the Cu B redox center -which plays the role of the proton loading site (PLS) of the pump. The mechanism of pumping is based on ET reaction between two hemes of the enzyme, which is coupled to a transfer of two protons. Upon ET, the first proton (fast reaction) is transferred to the PLS (His291), while subsequent transfer of the second ''chemical'' proton to the binuclear center (slow reaction) is accompanied by the ejection of the first (pumped) proton. Within the proposed model, we discuss the catalytic cycle of the enzyme.

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Section: ''Psupporting

confidence: 65%

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

POPOVI

2004

FEBS Letters

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“…It is intriguing that two terminal "oxidases," which couple small- molecule reduction to ATP synthesis, both apparently contain a CuA-type site. CUA has been proposed to be a protonpumping site in cytochrome c oxidase (42,43) although there is some disagreement about this (44). The occurrence of a CuA-type site in these enzymes, and to date in no other type of enzyme to the best of our knowledge, suggests that CUA may have evolved to fulfill a particular role in energyconserving electron-transport chains, whatever that role may turn out to be.…”

Section: Resultsmentioning

confidence: 95%

Pseudomonas stutzeri N2O reductase contains CuA-type sites.

Scott

Zumft

Coyle

et al. 1989

Proc. Natl. Acad. Sci. U.S.A.

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N2O reductase (N2O----N2) is the terminal enzyme in the energy-conserving denitrification pathway of soil and marine denitrifying bacteria. The protein is composed of two identical subunits and contains eight copper ions per enzyme molecule. The magnetic circular dichroism spectrum of resting (oxidized) N2O reductase is strikingly similar to the magnetic circular dichroism spectrum of the CuA site in mammalian cytochrome c oxidase [Greenwood, C., Hull, B. C., Barber, D., Eglinton, D. G. & Thomson, A. J. (1983) Biochem. J. 215, 303-316] and is unlike the magnetic circular dichroism spectra of all other biological copper chromophores obtained to date. Sulfur (or chlorine) scatterers are required to fit the copper extended x-ray absorption fine structure data of both the oxidized and reduced forms of N2O reductase. Satisfactory fits require a Cu-N or Cu-O [denoted Cu-(N, O)] interaction at 2.0 A, a Cu-(S, Cl) interaction at 2.3 A and an additional Cu(S, Cl) interaction at approximately 2.6 A (oxidized) or approximately 2.7 A (reduced). Approximately eight sulfur ions (per eight copper ions) at approximately 2.3 A are required to fit the extended x-ray absorption fine structure data for both the oxidized and reduced N2O reductase. The 2.3-A Cu-(S, Cl) distance is nearly identical to that previously determined for the CuA site in cytochrome c oxidase. A 2.6-2.7 A Cu-(S, Cl) interaction is also present in resting and fully reduced cytochrome c oxidase. Comparison of the N2O reductase sequence, determined by translating the structural NosZ gene, with cytochrome c oxidase subunit II sequences from several sources indicates that a Gly-Xaa-Xaa-Xaa-Xaa-Xaa-Cys-Ser-Xaa-Xaa-Cys-Xaa-Xaa-Xaa-His stretch is highly conserved. This sequence contains three of the probable ligands (two cysteines and one histidine) in a CuA-type site. Collectively these data establish that Pseudomonas stutzeri N2O reductase contains CuA-type sites.

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“…However, these experiments were carried out at only a single cytochrome c and reductant concentration, and it is clear that there are at least three variables that can be affected by the ionophores in such experiments: the quasi-equilibrium between cytochromes c and a, the irnmediate flux to oxygen, and the maximal velocity (rate constant from cytochrome oxidation). As emphasized by Rich et al (1988), it may also be useful to try and distinguish control points from energy-conserving steps in the overall reaction of the oxidase. According to these workers the Biochem.…”

Section: Resultsmentioning

confidence: 99%

“…The first approach (see, e.g., Hinkle and Mitchell 1970;Moroney et al 1984; ABBREVIATIONS: TMPD, N,N,N1,N' -tetramethyl-p-phenylenediamine; FCCP, carbonylcyanide p-trifluoromethoxyphenylhydrazone; cyt., cytochrome. Rich et al 1988;Gregory and Ferguson-Miller 1989;Wikstrom 1988) treats the control as basically thermodynamic in nature, albeit exerted, perhaps, on partial reactions of the oxidase. Workers adopting this approach, therefore, see their task as identifying the reactions involved and their contribution to the overall process.…”

Section: Introductionmentioning

confidence: 98%

Control of proteoliposomal cytochrome c oxidase: the partial reactions

Nicholls

1990

Biochem. Cell Biol.

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The steady-state spectroscopic behaviour and the turnover of cytochrome c oxidase incorporated into proteoliposomes have been investigated as functions of membrane potential and pH gradient. The respiration rate is almost linearly dependent on [cytochrome c2+] at high flux, but while the cytochrome a redox state is always dependent on the [cytochrome c2+] steady state, it reaches a maximum reduction level less than 100% in each case. The maximal aerobic steady-state reduction level of cytochrome a is highest in the presence of valinomycin and lowest in the presence of nigericin. The proportion of [cytochrome c2+] required to achieve 50% of maximal reduction of cytochrome a varies with the added ionophores; the apparent redox potential of cytochrome a is most positive in the fully decontrolled system (plus valinomycin and nigericin). At low levels of cytochrome a reduction, the rate of respiration is no longer a linear function of [cytochrome c2+], but is dependent upon the redox state of both cytochromes a and c. That is, proteoliposomal oxidase does not follow Smith-Conrad kinetics at low cytochrome c reduction levels, especially in the controlled states. The control of cytochrome oxidase turnover by delta pH and by delta psi can be explained either by an allosteric model or by a model with reversed electron transfer between the binuclear centre and cytochrome a. Other evidence suggests that the reversed electron transfer model may be the correct one.

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The location of Cu_A in mammalian cytochrome c oxidase

Cited by 58 publications

References 25 publications

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

Pseudomonas stutzeri N2O reductase contains CuA-type sites.

Control of proteoliposomal cytochrome c oxidase: the partial reactions

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The location of CuA in mammalian cytochrome c oxidase

Cited by 58 publications

References 25 publications

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

Proton pumping mechanism and catalytic cycle of cytochrome c oxidase: Coulomb pump model with kinetic gating

Pseudomonas stutzeri N2O reductase contains CuA-type sites.

Control of proteoliposomal cytochrome c oxidase: the partial reactions

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The location of Cu_A in mammalian cytochrome c oxidase