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Modulation of the electron-proton coupling at cytochrome a by the ligation of the oxidized catalytic center in bovine cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148237. [PMID: 32485159 DOI: 10.1016/j.bbabio.2020.148237] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/29/2020] [Accepted: 05/25/2020] [Indexed: 11/20/2022]
Abstract
Cytochrome a was suggested as the key redox center in the proton pumping process of bovine cytochrome c oxidase (CcO). Recent studies showed that both the structure of heme a and its immediate vicinity are sensitive to the ligation and the redox state of the distant catalytic center composed of iron of cytochrome a3 (Fea3) and copper (CuB). Here, the influence of the ligation at the oxidized Fea33+-CuB2+ center on the electron-proton coupling at heme a was examined in the wide pH range (6.5-11). The strength of the coupling was evaluated by the determination of pH dependence of the midpoint potential of heme a (Em(a)) for the cyanide (the low-spin Fea33+) and the formate-ligated CcO (the high-spin Fea33+). The measurements were performed under experimental conditions when other three redox centers of CcO are oxidized. Two slightly differing linear pH dependencies of Em(a) were found for the CN- and the formate-ligated CcO with slopes of -13 mV/pH unit and -23 mV/pH unit, respectively. These linear dependencies indicate only a weak and unspecific electron-proton coupling at cytochrome a in both forms of CcO. The lack of the strong electron-proton coupling at the physiological pH values is also substantiated by the UV-Vis absorption and electron-paramagnetic resonance spectroscopy investigations of the cyanide-ligated oxidized CcO. It is shown that the ligand exchange at Fea3+ between His-Fea3+-His and His-Fea3+-OH- occurs only at pH above 9.5 with the estimated pK >11.0.
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2
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Electron transfer between cytochrome c and the binuclear center of cytochrome oxidase. J Theor Biol 2019; 460:134-141. [DOI: 10.1016/j.jtbi.2018.10.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/05/2018] [Accepted: 10/08/2018] [Indexed: 12/22/2022]
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3
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Rocha MC, Springett R. Spectral components of detergent-solubilized bovine cytochrome oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:555-566. [PMID: 29704499 DOI: 10.1016/j.bbabio.2018.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 03/21/2018] [Accepted: 04/23/2018] [Indexed: 11/27/2022]
Abstract
Cytochrome oxidase is the terminal oxidase of the mitochondrial electron transport chain and pumps 4 protons per oxygen reduced to water. Spectral shifts in the α-band of heme a have been observed in multiple studies and these shifts have the potential to shed light on the proton pumping intermediates. Previously we found that heme a had two spectral components in the α-band during redox titrations in living RAW 264.7 mouse macrophage cells, the classical 605 nm form and a blue-shifted 602 nm form. To confirm these spectral changes were not an artifact due to the complex milieu of the living cell, redox titrations were performed in the isolated detergent-solubilized bovine enzyme from both the Soret- and α-band using precise multiwavelength spectroscopy. This data verified the presence of the 602 nm form in the α-band, revealed a similar shift of heme a in the Soret-band and ruled out the reversal of calcium binding as the origin of the blue shift. The 602 nm form was found to be stabilized at high pH or by binding of azide, which is known to blue shift the α-band of heme a. Azide also stabilized the 602 nm form in the living cells. It is concluded there is a form of cytochrome oxidase in which heme a undergoes a blue shift to a 602 nm form and that redox titrations can be successfully performed in living cells where the oxidase operates in its authentic environment and in the presence of a proton motive force.
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Affiliation(s)
- Mariana C Rocha
- Cardiovascular Division, King's College London, British Heart Foundation Centre of Excellence, 125 Coldharbour Lane, London SE5 9NU, United Kingdom
| | - Roger Springett
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, United Kingdom.
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Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1138] [Impact Index Per Article: 113.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
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Ashe D, Alleyne T, Sampson V. Substrate binding-dissociation and intermolecular electron transfer in cytochrome c oxidase are driven by energy-dependent conformational changes in the enzyme and substrate. Biotechnol Appl Biochem 2013; 59:213-22. [PMID: 23586831 DOI: 10.1002/bab.1015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 02/23/2012] [Indexed: 12/21/2022]
Abstract
Reduction of O₂ by cytochrome c oxidase (COX) is critical to the cellular production of adenosine-5'-triphosphate; COX obtains the four electrons required for this process from ferrocytochrome c. The COX-cytochrome c enzyme-substrate complex is stabilized by electrostatic interactions via carboxylates on COX and lysines on cytochrome c. Conformational changes are believed to play a role in ferrocytochrome c oxidation and release and in rapid intramolecular transfer of electrons within COX, but the details are unclear. To gather specific information about the extent and relevance of conformational changes, we performed bioinformatics studies using the published structures of both proteins. For both proteins, we studied the surface accessibility and energy, as a function of the proteins' oxidation state. The residues of reduced cytochrome c showed greater surface accessibility and were at a higher energy than those of the oxidized cytochrome c. Also, most residues of the core subunits (I, II, and III) of COX showed low accessibility, ∼35%, and compared to the oxidized subunits, the reduced subunits had higher energies. We concluded that substrate binding and dissociation is modulated by specific redox-dependent conformational changes. We further conclude that high energy and structural relaxation of reduced cytochrome c and core COX subunits drive their rapid electron transfer.
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Affiliation(s)
- Damian Ashe
- Department of Preclinical Sciences, Biochemistry Unit, Faculty of Medical Sciences, The University of the West Indies, St. Augustine, Trinidad, West Indies
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6
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Kim N, Ripple MO, Springett R. Spectral components of the α-band of cytochrome oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:779-87. [PMID: 21420929 DOI: 10.1016/j.bbabio.2011.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 03/11/2011] [Accepted: 03/15/2011] [Indexed: 11/30/2022]
Abstract
Oxidative redox titrations of the mitochondrial cytochromes were performed in near-anoxic RAW 264.7 cells by inhibiting complex I. Cytochrome oxidation changes were measured with multi-wavelength spectroscopy and the ambient redox potential was calculated from the oxidation state of endogenous cytochrome c. Two spectral components were separated in the α-band range of cytochrome oxidase and they were identified as the difference spectrum of heme a when it has a high (a(H)) or low (a(L)) midpoint potential (E(m)) by comparing their occupancy during redox titrations carried out when the membrane potential (ΔΨ) was dissipated with a protonophore to that predicted by the neoclassical model of redox cooperativity. The difference spectrum of a(L) has a maximum at 605nm whereas the spectrum of a(H) has a maximum at 602nm. The ΔΨ-dependent shift in the E(m) of a(H) was too great to be accounted for by electron transfer from cytochrome c to heme a against ΔΨ but was consistent with a model in which a(H) is formed after proton uptake against ΔΨ suggesting that the spectral changes are the result of protonation. A stochastic simulation was implemented to model oxidation states, proton uptake and E(m) changes during redox titrations. The redox anti-cooperativity between heme a and heme a(3), and proton binding, could be simulated with a model where the pump proton interacted with heme a and the substrate proton interacted with heme a(3) with anti-cooperativity between proton binding sites, but not with a single proton binding site coupled to both hemes.
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Affiliation(s)
- N Kim
- Department of Radiology, Dartmouth Medical School, Hanover, NH, USA
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7
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Brzezinski P, Sundahl M, Adelroth P, Wilson MT, el-Agez B, Wittung P, Malmström BG. Triplet-state quenching in complexes between Zn-cytochrome c and cytochrome oxidase or its CuA domain. Biophys Chem 1995; 54:191-7. [PMID: 7756569 DOI: 10.1016/0301-4622(94)00128-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The quenching of the triplet state of Zn-cytochrome c in electrostatic complexes with cytochrome oxidase and its soluble CuA domain has been studied by laser flash photolysis. The triplet state of free Zn-cytochrome c decayed with a rate of about 200 s-1. With the oxidase, biphasic decay with rate constants of 2 x 10(5) and 2 x 10(3) s-1, respectively, was observed. At high ionic strength (I = 0.2) the decay was the same as with free Zn-cytochrome c. The quenching was also eliminated by reduction of the oxidase. The decay rate in the complex with the CuA domain was 4 x 10(4) s-1. The results are interpreted in terms of rapid electron transfer to CuA and a slower one to cytochrome a. No electron transfer products were detected, because the backward reaction is faster than the forward one. This can be explained by the high driving force (1.1 eV) for the forward electron transfer, taking the system into the inverted Marcus region. The distance in the electrostatic complex between cytochrome c and the electron acceptor, presumed to be CuA, is calculated to be 16 A.
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Affiliation(s)
- P Brzezinski
- Department of Biochemistry and Biophysics, Göteborg University, Sweden
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Hendler RW, Bose SK, Shrager RI. Multiwavelength analysis of the kinetics of reduction of cytochrome aa3 by cytochrome c. Biophys J 1993; 65:1307-17. [PMID: 8241410 PMCID: PMC1225850 DOI: 10.1016/s0006-3495(93)81170-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Some new approaches to the kinetic study of the reduction of cytochrome aa3 by cytochrome c are presented. The primary innovations are the use of a spectrometer which can acquire multiwavelength data as fast as every 10 microseconds, and the application of a variety of analytical methods which can utilize simultaneously all of the time-resolved spectral data. These techniques include singular value decomposition (SVD), deconvolutions based on pure Gaussian models for absorption peaks, deconvolutions based on isolated absorption spectra for the pure components, and simulations of SVD-deduced and actual experimental difference spectra. The reduction characteristics of the anaerobic resting enzyme can be distinguished from those of pulsed forms. In the former case, only two electrons can be bound by cytochrome aa3, whereas in the latter case complete reduction of the enzyme is achieved.
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Affiliation(s)
- R W Hendler
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
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Affiliation(s)
- B G Malmström
- Department of Biochemistry and Biophysics, Göteborg University, Sweden
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Malatesta F, Antonini G, Sarti P, Vallone B, Brunori M. The kinetics of electron entry in cytochrome c oxidase. BIOLOGY OF METALS 1990; 3:118-21. [PMID: 1965780 DOI: 10.1007/bf01179517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The kinetics of electron entry in beef heart cytochrome c oxidase have been studied by stopped-flow spectroscopy following chemical modification of the CuA site with mercurials. In this derivative CuA is no longer reducible by cytochrome c while cytochrome alpha may accept electrons from the latter with rates comparable to the native enzyme. The results indicate that CuA is not the exclusive electron entry site in cytochrome c oxidase.
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Affiliation(s)
- F Malatesta
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Universitá di Roma Tor Vergata, Italy
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Affiliation(s)
- B G Malmström
- Department of Biochemistry and Biophysics, University of Göteborg, Sweden
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Malmström BG, Nilsson T. Intermediate states and electron gating in proton-pumping cytochrome c oxidase. Ann N Y Acad Sci 1988; 550:177-84. [PMID: 2854390 DOI: 10.1111/j.1749-6632.1988.tb35334.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- B G Malmström
- Department of Biochemistry and Biophysics, Chalmers University of Technology, Göteborg, Sweden
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13
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Abstract
A model for cytochrome oxidase is presented in which cytochrome a, cytochrome a3, and CuB are mutally interacting centers. Cytochrome a3, at equilibrium, is always reduced after CuB. The redox potential of cytochrome a declines progressively as the a3 CuB center is reduced. Dithionite reduction involves up to five steps: (i) reduction of cytochrome a and CuA; (ii) reduction of CuB; (iii) dissociation of ligands (exogenous and endogenous) from cytochrome a3; (iv) spin state changes (high to low) in cyt. a3 and (v) reduction of cytochrome a3. Any of (ii), (iii), and (iv) may be implicated as part of the slow step in this process, which is seen in the resting enzyme.
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Affiliation(s)
- P Nicholls
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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14
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Chemiosmotic coupling in cytochrome oxidase. Possible protonmotive O loop and O cycle mechanisms. FEBS Lett 1985; 188:1-7. [PMID: 2410291 DOI: 10.1016/0014-5793(85)80863-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Using the principle of specific vectorial ligand conduction, we outline directly coupled protonmotive O loop and O cycle mechanisms of cytochrome oxidase action that are analogous to protonmotive Q loop and Q cycle mechanisms of QH2 dehydrogenase action. We discuss these directly coupled mechanisms in the light of available experimental knowledge, and suggest that they may stimulate useful new research initiatives designed to elucidate the osmochemistry of protonmotive oxygen reduction in cytochrome oxidase.
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Malmström BG, Andréasson LE. The steady-state rate equation for cytochrome c oxidase based on a minimal kinetic scheme. J Inorg Biochem 1985; 23:233-42. [PMID: 2991462 DOI: 10.1016/0162-0134(85)85030-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A minimal catalytic cycle for cytochrome c oxidase has been suggested, and the steady-state kinetic equation for this mechanism has been derived. This equation has been used to simulate experimental data for the pH dependence of the steady-state kinetic parameters, kcat and Km. In the simulations the rate constants for binding and dissociation of cytochrome c and for two internal electron-transfer steps have been allowed to vary, whereas fixed experimental values (for pH 7.4) have been used for the other rate constants. The results show that the dissociation of the product, ferricytochrome c, cannot be rate-limiting under all conditions, but that intramolecular electron-transfer steps also limit the rate. They also demonstrate that Km can differ considerably from the dissociation constant for the cytochrome c-oxidase complex. Published values for the rate constant for the dissociation of ferricytochrome c are too small to account for the steady-state rates. It is suggested that, at high concentrations, ferryocytochrome c transfers an electron to a cytochrome c molecule which remains bound to the oxidase. This can also explain the nonhyperbolic kinetics, which is observed at low substrate concentrations.
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18
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Further characterization of the potentiometric behavior of cytochrome oxidase. Cytochrome alpha stays low spin during oxidation and reduction. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43749-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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19
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Models of the two heme centers in cytochrome oxidase. The optical properties of cytochrome a and a3. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33476-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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20
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Antalis TM, Palmer G. Kinetic characterization of the interaction between cytochrome oxidase and cytochrome c. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(20)65125-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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21
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Wilson MT, Jensen P, Aasa R, Malmström BG, Vänngård T. An investigation by e.p.r. and optical spectroscopy of cytochrome oxidase during turnover. Biochem J 1982; 203:483-92. [PMID: 6288002 PMCID: PMC1158254 DOI: 10.1042/bj2030483] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cytochrome oxidase (EC 1.9.3.1; ferrocytochrome c:oxygen oxidoreductase) was studied during steady-state by optical and e.p.r. methods. Starting with either the 'resting' or the 'pulsed' enzyme, oxidase, cytochrome c, ascorbate and O2 were mixed and the reaction monitored optically. Tetramethylphenylenediamine was used as mediator to poise the steady-state to the desired reduction level. After mixing, the reaction was quenched by the used of rapid-freeze techniques. The e.p.r. spectra of samples captured at increasing tetramethylphenylenediamine concentrations (i.e. higher electron flux) show decreasing g = 2 (Cu A) and g = 3 (cytochrome a) signals. No Cu B or g = 6 signals (high-spin cytochrome a3) could be found during the reaction. Also, the signal with peaks at g = 1.69, 1.78 and 5 as well as the g = 12 signal was hardly detectable at higher turnover rates. The only new signal appearing during turnover is a radical signal, which is discussed in terms of a protein radical. Finally, a scheme is presented, proposing a catalytic cycle for cytochrome oxidase with respect to the O2 binding Cu B-cytochrome a3 unit.
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Wilms J, Veerman EC, König BW, Dekker HL, van Gelder BF. Ionic strength effects on cytochrome aa3 kinetics. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 635:13-24. [PMID: 6260160 DOI: 10.1016/0005-2728(81)90003-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. The occurrence of an optimal ionic strength for the steady-state activity of isolated cytochrome aa3 can be attributed to two opposite effects: upon lowering of the ionic strength the affinity between cytochrome c and cytochrome aa3 increases, whereas in the lower ionic strength region the formation of a less active cytochrome c-aa3 complex limits the ferrocytochrome c association to the low affinity site. 2. At low ionic strength, the reduction of cytochrome c-aa3 complex by ferrocytochrome c1 proceeds via non-complex-bound cytochrome c. Under these conditions the positively charged cytochrome c provides the electron transfer between the negatively charged cytochromes c1 and aa3. 3. Polylysine is found to stimulate the release of tightly bound cytochrome c from the cytochrome c-aa3 complex. This property points to the existence of negative cooperativity between the two binding sites. We suggest that the stimulation is not restricted to polylysine, but also occurs with cytochrome c. 4. Dissociation rates of both high and low affinity sites on cytochrome aa3 were determined indirectly. The dissociation constants, calculated on the basis of pre-steady-state reaction rates at an ionic strength of 8.8 mM, were estimated to be 0.6 nM and 20 microM for the high and low affinity site, respectively.
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23
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Halaka F, Babcock G, Dye J. Kinetic distinction between cytochromes a and a3 in cytochrome c oxidase. Rapid scanning stopped flow study of anaerobic reduction by a neutral and a negatively charged donor. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69926-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Hill BC, Nicholls P. Reduction and activity of cytochrome c in the cytochrome c-cytochrome aa3 complex. Biochem J 1980; 187:809-18. [PMID: 6331386 PMCID: PMC1162466 DOI: 10.1042/bj1870809] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Uncharged reductants, such as NNN'N'-tetramethyl-p-phenylenediamine and diaminodurene, reduce cytochrome c at both high and low ionic strength, unlike ascorbate, which is effective only at low ionic strength. The 'tightly bound' cytochrome c-cytochrome c oxidase complex, with 1 equiv. of cytochrome c per cytochrome aa3, can be prepared by simple mixing of the two component species. Its properties are not affected by co-sonication of the mixture. Bound cytochrome c is more rapidly reduced by NNN'N'-tetramethyl-p-phenylenediamine and diaminodurene than is free cytochrome c. At high ionic strength, when the complex is largely dissociated, addition of reductant under aerobic conditions in the presence of cyanide, or under anaerobic conditions, induces a rapid reduction of cytochrome c followed by the reduction of cytochrome a. At low ionic strength, addition of reductant induces a rapid reduction of cytochrome a while cytochrome c remains largely oxidized, the rate-limiting step now being the reduction of cytochrome c. The results are interpreted in terms of direct reduction of cytochrome c in its tight complex with the oxidase, followed by rapid intramolecular electron transfer to both cytochrome a and the associated e.p.r.-detectable Cu atom.
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Petersen LC, Cox RP. On the mechanism of the cytochrome c oxidase reaction. Bound Fe(III) cytochrome c as an intermediate in the reductive half reaction. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 105:321-7. [PMID: 6247151 DOI: 10.1111/j.1432-1033.1980.tb04504.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Brunori M, Colosimo A, Rainoni G, Wilson M, Antonini E. Functional intermediates of cytochrome oxidase. Role of “pulsed” oxidase in the pre-steady state and steady state reactions of the beef enzyme. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86588-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Rosén S. Kinetic studies on oxidized and partially reduced cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 503:389-97. [PMID: 210804 DOI: 10.1016/0005-2728(78)90196-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1. Kinetic studies have been performed with beef-heart cytochrome c oxidase, with the enzyme either in its oxidized, resting state or pretreated anaerobically with different amounts of reduced cytochrome c. The techniques used for the study have been stopped-flow spectrophotometry and electron paramagnetic resonance (EPR) spectroscopy. 2. The results show that the one-electron equivalent-reduced enzyme rapidly oxidizes one further equivalent of aerobically or anaerobically added ferrocytochrome c, with a rate constant of 5 . 10(6) M-1 . s-1. 3. When an excess of ferrocytochrome c in the presence of oxygen is added to the one-electron-reduced enzyme, the same turnover rate is obtained as in experiments with the resting enzyme. 4. The one-electron equivalent-enzyme reacts with CO with a rate constant of 4 . 10(4) M-1 . s-1 to yield approx. 35% of the CO compound as compared with the reaction between the fully reduced enzyme and CO. 5. It is shown that on reduction the enzyme is converted into an active form, but it is concluded that the enzyme does not have to be fully reduced before it is catalytically active.
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32
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Petersen LC. On the mechanism of the cytochrome c oxidase reaction. A study of the anaerobic-aerobic transition of the carbonmonoxide inhibited ascorbate leads to cytochrome c leads to cytochrome aa3 system. EUROPEAN JOURNAL OF BIOCHEMISTRY 1978; 85:339-44. [PMID: 206434 DOI: 10.1111/j.1432-1033.1978.tb12244.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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33
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Brautigan DL, Ferguson-Miller S, Margoliash E. Mitochondrial cytochrome c: preparation and activity of native and chemically modified cytochromes c. Methods Enzymol 1978; 53:128-64. [PMID: 213675 DOI: 10.1016/s0076-6879(78)53021-8] [Citation(s) in RCA: 313] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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34
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35
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Petersen LC, Andréasson LE. The reaction between oxidized cytochrome c and reduced cytochrome c oxidase. FEBS Lett 1976; 66:52-7. [PMID: 179895 DOI: 10.1016/0014-5793(76)80583-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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36
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Wikström KF, Harmon HJ, Ingledew WJ, Chance B. A re-evaluation of the spectral, potentiometric and energy-linked properties of cytochrome c oxidase in mitochondria. FEBS Lett 1976; 65:259-77. [PMID: 182532 DOI: 10.1016/0014-5793(76)80127-5] [Citation(s) in RCA: 144] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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37
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Mackey LN, Kuwana T. Spectroelectrochemical kinetic studies of cytochrome-c and cytochrome c oxidase. ACTA ACUST UNITED AC 1976. [DOI: 10.1016/0302-4598(76)80050-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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38
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