1
|
Quist DA, Diaz DE, Liu JJ, Karlin KD. Activation of dioxygen by copper metalloproteins and insights from model complexes. J Biol Inorg Chem 2017; 22:253-288. [PMID: 27921179 PMCID: PMC5600896 DOI: 10.1007/s00775-016-1415-2] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 11/11/2016] [Indexed: 02/08/2023]
Abstract
Nature uses dioxygen as a key oxidant in the transformation of biomolecules. Among the enzymes that are utilized for these reactions are copper-containing metalloenzymes, which are responsible for important biological functions such as the regulation of neurotransmitters, dioxygen transport, and cellular respiration. Enzymatic and model system studies work in tandem in order to gain an understanding of the fundamental reductive activation of dioxygen by copper complexes. This review covers the most recent advancements in the structures, spectroscopy, and reaction mechanisms for dioxygen-activating copper proteins and relevant synthetic models thereof. An emphasis has also been placed on cofactor biogenesis, a fundamentally important process whereby biomolecules are post-translationally modified by the pro-enzyme active site to generate cofactors which are essential for the catalytic enzymatic reaction. Significant questions remaining in copper-ion-mediated O2-activation in copper proteins are addressed.
Collapse
Affiliation(s)
- David A Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Daniel E Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Jeffrey J Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.
| |
Collapse
|
2
|
Szundi I, Kittredge C, Choi SK, McDonald W, Ray J, Gennis RB, Einarsdóttir Ó. Kinetics and Intermediates of the Reaction of Fully Reduced Escherichia coli bo3 Ubiquinol Oxidase with O2. Biochemistry 2014; 53:5393-404. [DOI: 10.1021/bi500567m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Istvan Szundi
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Clive Kittredge
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Sylvia K. Choi
- Department
of Biochemistry and the Center for Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, Illinois 61801, United States
| | - William McDonald
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Jayashree Ray
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Robert B. Gennis
- Department
of Biochemistry and the Center for Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, Illinois 61801, United States
| | - Ólöf Einarsdóttir
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| |
Collapse
|
3
|
Pinakoulaki E, Daskalakis V, Ohta T, Richter OMH, Budiman K, Kitagawa T, Ludwig B, Varotsis C. The protein effect in the structure of two ferryl-oxo intermediates at the same oxidation level in the heme copper binuclear center of cytochrome c oxidase. J Biol Chem 2013; 288:20261-6. [PMID: 23723073 DOI: 10.1074/jbc.m113.468488] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Identification of the intermediates and determination of their structures in the reduction of dioxygen to water by cytochrome c oxidase (CcO) are particularly important to understanding both O2 activation and proton pumping by the enzyme. In this work, we report the products of the rapid reaction of O2 with the mixed valence form (CuA(2+), heme a(3+), heme a3(2+)-CuB(1+)) of the enzyme. The resonance Raman results show the formation of two ferryl-oxo species with characteristic Fe(IV)=O stretching modes at 790 and 804 cm(-1) at the peroxy oxidation level (PM). Density functional theory calculations show that the protein environment of the proximal H-bonded His-411 determines the strength of the distal Fe(IV)=O bond. In contrast to previous proposals, the PM intermediate is also formed in the reaction of Y167F with O2. These results suggest that in the fully reduced enzyme, the proton pumping ν(Fe(IV)=O) = 804 cm(-1) to ν(Fe(IV)=O) = 790 cm(-1) transition (P→F, where P is peroxy and F is ferryl) is triggered not only by electron transfer from heme a to heme a3 but also by the formation of the H-bonded form of the His-411-Fe(IV)=O conformer in the proximal site of heme a3. The implications of these results with respect to the role of an O=Fe(IV)-His-411-H-bonded form to the ring A propionate of heme a3-Asp-399-H2O site and, thus, to the exit/output proton channel (H2O) pool during the proton pumping P→F transition are discussed. We propose that the environment proximal to the heme a3 controls the spectroscopic properties of the ferryl intermediates in cytochrome oxidases.
Collapse
Affiliation(s)
- Eftychia Pinakoulaki
- Department of Chemistry, University of Cyprus, P. O. Box 20537, 1678 Nicosia, Cyprus
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Gorbikova EA, Wikström M, Verkhovsky MI. The protonation state of the cross-linked tyrosine during the catalytic cycle of cytochrome c oxidase. J Biol Chem 2008; 283:34907-12. [PMID: 18931371 DOI: 10.1074/jbc.m803511200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome c oxidase is the terminal complex of the respiratory chain in mitochondria and some aerobic bacteria and is responsible for most of the O(2) consumption in biology. The key reaction in the catalysis of O(2) reduction is O-O bond scission that requires four electrons and a proton. In our recent work (Gorbikova, E. A., Belevich, I., Wikstrom, M., and Verkhovsky, M. I. (2008) Proc. Natl. Acad. Sci. U. S. A. 105, 10733-10737), it was shown that the cross-linked Tyr-280 (Paracoccus denitrificans numbering) provides the proton for O-O bond cleavage. The deprotonated Tyr-280 must be reprotonated later on in the catalytic cycle to serve as a proton donor for the next oxygen reduction event. To find the reaction step at which the cross-linked Tyr-280 becomes reprotonated, all further steps of the catalytic cycle after O-O bond cleavage were followed by infrared spectroscopy. We found that complete reprotonation of the tyrosine is linked to the formation of the one-electron reduced state coupled to reduction of the Cu(B) site.
Collapse
Affiliation(s)
- Elena A Gorbikova
- Helsinki Bioenergetics Group, Institute of Biotechnology, University of Helsinki, P. O. Box 65, Viikinkaari 1, FI-00014 Helsinki, Finland
| | | | | |
Collapse
|
5
|
Belevich I, Verkhovsky MI. Molecular mechanism of proton translocation by cytochrome c oxidase. Antioxid Redox Signal 2008; 10:1-29. [PMID: 17949262 DOI: 10.1089/ars.2007.1705] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cytochrome c oxidase (CcO) is a terminal protein of the respiratory chain in eukaryotes and some bacteria. It catalyzes most of the biologic oxygen consumption on earth done by aerobic organisms. During the catalytic reaction, CcO reduces dioxygen to water and uses the energy released in this process to maintain the electrochemical proton gradient by functioning as a redox-linked proton pump. Even though the structures of several terminal oxidases are known, they are not sufficient in themselves to explain the molecular mechanism of proton pumping. Thus, additional extensive studies of CcO by varieties of biophysical and biochemical approaches are involved to shed light on the mechanism of proton translocation. In this review, we summarize the current level of knowledge about CcO, including the latest model developed to explain the CcO proton-pumping mechanism.
Collapse
Affiliation(s)
- Ilya Belevich
- Helsinki Bioenergetics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | | |
Collapse
|
6
|
Oxygen Activation Mechanism at the Binuclear Site of Heme-Copper Oxidase Superfamily as Revealed by Time-Resolved Resonance Raman Spectroscopy. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/9780470166468.ch6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
|
7
|
Musser SM, Stowell MH, Chan SI. Cytochrome c oxidase: chemistry of a molecular machine. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 71:79-208. [PMID: 8644492 DOI: 10.1002/9780470123171.ch3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The plethora of proposed chemical models attempting to explain the proton pumping reactions catalyzed by the CcO complex, especially the number of recent models, makes it clear that the problem is far from solved. Although we have not discussed all of the models proposed to date, we have described some of the more detailed models in order to illustrate the theoretical concepts introduced at the beginning of this section on proton pumping as well as to illustrate the rich possibilities available for effecting proton pumping. It is clear that proton pumping is effected by conformational changes induced by oxidation/reduction of the various redox centers in the CcO complex. It is for this reason that the CcO complex is called a redox-linked proton pump. The conformational changes of the proton pump cycle are usually envisioned to be some sort of ligand-exchange reaction arising from unstable geometries upon oxidation/reduction of the various redox centers. However, simple geometrical rearrangements, as in the Babcock and Mitchell models are also possible. In any model, however, hydrogen bonds must be broken and reformed due to conformational changes that result from oxidation/reduction of the linkage site during enzyme turnover. Perhaps the most important point emphasized in this discussion, however, is the fact that proton pumping is a directed process and it is electron and proton gating mechanisms that drive the proton pump cycle in the forward direction. Since many of the models discussed above lack effective electron and/or proton gating, it is clear that the major difficulty in developing a viable chemical model is not formulating a cyclic set of protein conformational changes effecting proton pumping (redox linkage) but rather constructing the model with a set of physical constraints so that the proposed cycle proceeds efficiently as postulated. In our discussion of these models, we have not been too concerned about which electron of the catalytic cycle was entering the site of linkage, but merely whether an ET to the binuclear center played a role. However, redox linkage only occurs if ET to the activated binuclear center is coupled to the proton pump. Since all of the models of proton pumping presented here, with the exception of the Rousseau expanded model and the Wikström model, have a maximum stoichiometry of 1 H+/e-, they inadequately explain the 2 H+/e- ratio for the third and fourth electrons of the dioxygen reduction cycle (see Section V.B). One way of interpreting this shortfall of protons is that the remaining protons are pumped by an as yet undefined indirectly coupled mechanism. In this scenario, the site of linkage could be coupled to the pumping of one proton in a direct fashion and one proton in an indirect fashion for a given electron. For a long time, it was assumed that at least some elements of such an indirect mechanism reside in subunit III. While recent evidence argues against the involvement of subunit III in the proton pump, subunit III may still participate in a regulatory and/or structural capacity (Section II.E). Attention has now focused on subunits I and II in the search for residues intimately involved in the proton pump mechanism and/or as part of a proton channel. In particular, the role of some of the highly conserved residues of helix VIII of subunit I are currently being studied by site directed mutagenesis. In our opinion, any model that invokes heme alpha 3 or CuB as the site of linkage must propose a very effective means by which the presumedly fast uncoupling ET to the dioxygen intermediates is prevented. It is difficult to imagine that ET over the short distance from heme alpha 3 or CuB to the dioxygen intermediate requires more than 1 ns. In addition, we expect the conformational changes of the proton pump to require much more than 1 ns (see Section V.B).
Collapse
Affiliation(s)
- S M Musser
- Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena 91125, USA
| | | | | |
Collapse
|
8
|
Konishi K, Ohta T, Oinuma KI, Hashimoto Y, Kitagawa T, Kobayashi M. Discovery of a reaction intermediate of aliphatic aldoxime dehydratase involving heme as an active center. Proc Natl Acad Sci U S A 2006; 103:564-8. [PMID: 16407114 PMCID: PMC1334632 DOI: 10.1073/pnas.0505412103] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, we discovered an intriguing hemoprotein [aliphatic aldoxime dehydratase (OxdA)] that catalyzes the dehydration of aliphatic aldoximes [R-CH=N-OH] to the corresponding nitriles [R-C identical withN] in the industrial Pseudomonas chlororaphis B23 strain. Unlike the utilization of H(2)O(2) or O(2) as a mediator of the catalysis by other heme-containing enzymes (e.g., P450), OxdA is notable for the direct binding of a substrate to the heme iron, experimental evidence of which was obtained here by means of resonance Raman (RR) analysis with an isotope technique. We found that the addition of a large amount of butyraldoxime (final concentration, 200 mM) to ferrous OxdA with a low enzyme concentration (final concentration, 5 muM) yields a long-lived OxdA-substrate complex (named OS-II), whose UV-vis spectrum is different from the corresponding spectra of the OxdA-substrate complex I and CO-bound, ferrous, and ferric forms of OxdA. Intriguingly, the RR analysis demonstrated that OS-II includes a highly oxidized heme with strong bonding between a substrate and the heme iron, as judged from the heme oxidation state marker nu(4) band at 1,379 cm(-1) and the (15)N-isotope-substituted butyraldoxime sensitive band at 857 cm(-1) in the RR spectra. It is noteworthy that OS-II has a highly oxidized heme like the ferryl-oxo heme species (e.g., compound II) formed by some general hemoproteins, although the function of OxdA is different from those (transport of electrons, transport of oxygen, sensing of oxygen or carbon monoxide, and catalysis of redox reactions) of general hemoproteins.
Collapse
Affiliation(s)
- Kazunobu Konishi
- Institute of Applied Biochemistry, and Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | | | | | | | | | | |
Collapse
|
9
|
Einarsdóttir O, Szundi I. Time-resolved optical absorption studies of cytochrome oxidase dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1655:263-73. [PMID: 15100041 DOI: 10.1016/j.bbabio.2003.07.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2003] [Accepted: 07/31/2003] [Indexed: 10/26/2022]
Abstract
Time-resolved spectroscopic studies in our laboratory of bovine heart cytochrome c oxidase dynamics are summarized. Intramolecular electron transfer was investigated upon photolysis of CO from the mixed-valence enzyme, by pulse radiolysis, and upon light-induced electron injection into the cytochrome c/cytochrome oxidase complex from a novel photoactivatable dye. The reduction of dioxygen to water was monitored by a gated multichannel analyzer using the CO flow-flash method or a synthetic caged dioxygen carrier. The pH dependence of the intermediate spectra suggests a mechanism of dioxygen reduction more complex than the conventional unidirectional sequential scheme. A branched model is proposed, in which one branch produces the P form and the other branch the F form. The rate of exchange between the two branches is pH-dependent. A cross-linked histidine-phenol was synthesized and characterized to explore the role of the cross-linked His-Tyr cofactor in the function of the enzyme. Time-resolved optical absorption spectra, EPR and FTIR spectra of the compound generated after UV photolysis indicated the presence of a radical residing primarily on the phenoxyl ring. The relevance of these results to cytochrome oxidase function is discussed.
Collapse
Affiliation(s)
- Olöf Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
| | | |
Collapse
|
10
|
Pinakoulaki E, Pfitzner U, Ludwig B, Varotsis C. Direct detection of Fe(IV)[double bond]O intermediates in the cytochrome aa3 oxidase from Paracoccus denitrificans/H2O2 reaction. J Biol Chem 2003; 278:18761-6. [PMID: 12637529 DOI: 10.1074/jbc.m211925200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report the first evidence for the formation of the "607- and 580-nm forms" in the cytochrome oxidase aa3/H2O2 reaction without the involvement of tyrosine 280. The pKa of the 607-580-nm transition is 7.5. The 607-nm form is also formed in the mixed valence cytochrome oxidase/O2 reaction in the absence of tyrosine 280. Steady-state resonance Raman characterization of the reaction products of both the wild-type and Y280H cytochrome aa3 from Paracoccus denitrificans indicate the formation of six-coordinate low spin species, and do not support, in contrast to previous reports, the formation of a porphyrin pi-cation radical. We observe three oxygen isotope-sensitive Raman bands in the oxidized wild-type aa3/H2O2 reaction at 804, 790, and 358 cm-1. The former two are assigned to the Fe(IV)[double bond]O stretching mode of the 607- and 580-nm forms, respectively. The 14 cm-1 frequency difference between the oxoferryl species is attributed to variations in the basicity of the proximal to heme a3 His-411, induced by the oxoferryl conformations of the heme a3-CuB pocket during the 607-580-nm transition. We suggest that the 804-790 cm-1 oxoferryl transition triggers distal conformational changes that are subsequently communicated to the proximal His-411 heme a3 site. The 358 cm-1 mode has been found for the first time to accumulate with the 804 cm-1 mode in the peroxide reaction. These results indicate that the mechanism of oxygen reduction must be reexamined.
Collapse
|
11
|
Rousseau DL, Han S. Time-resolved resonance Raman spectroscopy of intermediates in cytochrome oxidase. Methods Enzymol 2003; 354:351-68. [PMID: 12418239 DOI: 10.1016/s0076-6879(02)54028-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- Denis L Rousseau
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | |
Collapse
|
12
|
Schultz BE, Chan SI. Structures and proton-pumping strategies of mitochondrial respiratory enzymes. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2001; 30:23-65. [PMID: 11340051 DOI: 10.1146/annurev.biophys.30.1.23] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Enzymes of the mitochondrial respiratory chain serve as proton pumps, using the energy made available from electron transfer reactions to transport protons across the inner mitochondrial membrane and create an electrochemical gradient used for the production of ATP. The ATP synthase enzyme is reversible and can also serve as a proton pump by coupling ATP hydrolysis to proton translocation. Each of the respiratory enzymes uses a different strategy for performing proton pumping. In this work, the strategies are described and the structural bases for the action of these proteins are discussed in light of recent crystal structures of several respiratory enzymes. The mechanisms and efficiency of proton translocation are also analyzed in terms of the thermodynamics of the substrate transformations catalyzed by these enzymes.
Collapse
Affiliation(s)
- B E Schultz
- Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | | |
Collapse
|
13
|
Han S, Takahashi S, Rousseau DL. Time dependence of the catalytic intermediates in cytochrome c oxidase. J Biol Chem 2000; 275:1910-9. [PMID: 10636892 DOI: 10.1074/jbc.275.3.1910] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome c oxidase, the terminal enzyme in the electron transfer chain, catalyzes the reduction of oxygen to water in a multiple step process by utilizing four electrons from cytochrome c. To study the reaction mechanism, the resonance Raman spectra of the intermediate states were measured during single turnover of the enzyme after catalytic initiation by photolysis of CO from the fully reduced CO-bound enzyme. By measuring the change in intensity of lines associated with heme a, the electron transfer steps were determined and found to be biphasic with apparent rate constants of approximately 40 x 10(3) s(-1) and approximately 1 x 10(3) s(-1). The time dependence for the oxidation of heme a and for the measured formation and decay of the oxy, the ferryl ("F"), and the hydroxy intermediates could be simulated by a simple reaction scheme. In this scheme, the presence of the "peroxy" ("P") intermediate does not build up a sufficient population to be detected because its decay rate is too fast in buffered H(2)O at neutral pH. A comparison of the change in the spin equilibrium with the formation of the hydroxy intermediate demonstrates that this intermediate is high spin. We also confirm the presence of an oxygen isotope-sensitive line at 355 cm(-1), detectable in the spectrum from 130 to 980 micros, coincident with the presence of the F intermediate.
Collapse
Affiliation(s)
- S Han
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | |
Collapse
|
14
|
Michel H, Behr J, Harrenga A, Kannt A. Cytochrome c oxidase: structure and spectroscopy. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 1998; 27:329-56. [PMID: 9646871 DOI: 10.1146/annurev.biophys.27.1.329] [Citation(s) in RCA: 341] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cytochrome c oxidase, the terminal enzyme of the respiratory chains of mitochondria and aerobic bacteria, catalyzes electron transfer from cytochrome c to molecular oxygen, reducing the latter to water. Electron transfer is coupled to proton translocation across the membrane, resulting in a proton and charge gradient that is then employed by the F0F1-ATPase to synthesize ATP. Over the last years, substantial progress has been made in our understanding of the structure and function of this enzyme. Spectroscopic techniques such as EPR, absorbance and resonance Raman spectroscopy, in combination with site-directed mutagenesis work, have been successfully applied to elucidate the nature of the cofactors and their ligands, to identify key residues involved in proton transfer, and to gain insight into the catalytic cycle and the structures of its intermediates. Recently, the crystal structures of a bacterial and a mitochondrial cytochrome c oxidase have been determined. In this review, we provide an overview of the crystal structures, summarize recent spectroscopic work, and combine structural and spectroscopic data in discussing mechanistic aspects of the enzyme. For the latter, we focus on the structure of the oxygen intermediates, proton-transfer pathways, and the much-debated issue of how electron transfer in the enzyme might be coupled to proton translocation.
Collapse
Affiliation(s)
- H Michel
- Max-Planck-Institut für Biophysik, Frankfurt/Main, Germany.
| | | | | | | |
Collapse
|
15
|
Fabian M, Palmer G. Hydrogen peroxide is not released following reaction of cyanide with several catalytically important derivatives of cytochrome c oxidase. FEBS Lett 1998; 422:1-4. [PMID: 9475157 DOI: 10.1016/s0014-5793(97)01561-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have looked for the production of hydrogen peroxide following reaction of oxidized cytochrome c oxidase and two oxy derivatives (compounds P and F) with cyanide. In each case the final product was the cyanide adduct of cytochrome c oxidase. In no case release of hydrogen peroxide was detected, as gauged by the scopoletin plus horse radish peroxidase assay. The simplest conclusion is that none of these forms of the enzyme contains intact hydrogen peroxide.
Collapse
Affiliation(s)
- M Fabian
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005-1892, USA
| | | |
Collapse
|
16
|
Fujiwara T, Sakai H, Kumamaru T. EFFECT OF IRON(III) ON CHEMILUMINESCENCE FROM THE NEUTRALIZATION REACTION OF NITRIC ACID and POTASSIUM HYDROXIDE. Photochem Photobiol 1995. [DOI: 10.1111/j.1751-1097.1995.tb02365.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
17
|
Varotsis C, Babcock GT, Lauraeus M, Wikström M. Raman detection of a peroxy intermediate in the hydroquinone-oxidizing cytochrome aa3 of Bacillus subtilis. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1231:111-6. [PMID: 7640289 DOI: 10.1016/0005-2728(95)00076-u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
When the mixed valence, carbon monoxide-bound form of the hydroquinone-oxidizing cytochrome aa3-600 of Bacillus subtilis is illuminated in the presence of O2, it forms a species that corresponds to 'Compound C', first described for the mitochondrial cytochrome c oxidase by Chance, Saronio and Leigh (J. Biol. Chem. 250 (1975) 9226-9237). Resonance Raman spectra of the this species show a mode at 366 cm-1 that shifts to 342 cm-1 when the experiment is repeated with 18O2. The appearance of this mode is insensitive to deuteration exchange within the limits of resolution. High- (1200-1700 cm-1) and low-frequency (200-500 cm-1) data, allow us to assign the 366 cm-1 mode to the Fe(3+)-O stretching vibration of a peroxide adduct where the iron is either low or intermediate spin. This is to our knowledge the first time an 18O2-sensitive iron-oxygen stretching mode has been reported for 'Compound C', providing strong support for the notion that this species is a peroxide adduct. The observed 366 cm-1 v(Fe(3+)-O(-)-O-) frequency is 8 cm-1 higher than that previously found for a transient peroxy intermediate in the reaction between the fully reduced mitochondrial enzyme and O2. Our observation indicates that, while similar, the metastable peroxyheme a3 species reported here differs in the fine details of geometry, protonation state, and/or hydrogen bond status.
Collapse
Affiliation(s)
- C Varotsis
- Department of Chemistry, University of Crete, Iraklion, Greece
| | | | | | | |
Collapse
|
18
|
Affiliation(s)
- O Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz 95064, USA
| |
Collapse
|
19
|
|
20
|
Hirota S, Mogi T, Ogura T, Hirano T, Anraku Y, Kitagawa T. Observation of the Fe-O2 and FeIV=O stretching Raman bands for dioxygen reduction intermediates of cytochrome bo isolated from Escherichia coli. FEBS Lett 1994; 352:67-70. [PMID: 7925945 DOI: 10.1016/0014-5793(94)00919-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Reaction intermediates in dioxygen reduction by the E. coli cytochrome bo-type ubiquinol oxidase were studied by time-resolved resonance Raman spectroscopy using the artificial cardiovascular system. At 0-20 microseconds following photolysis of the enzyme-CO adduct in the presence of O2, we observed the Fe-O2 stretching Raman band at 568 cm-1 which shifted to 535 cm-1 with the 18O2 derivative. These frequencies are remarkably close to those of other oxyhemoproteins including dioxygen-bound hemoglobin and aa3-type cytochrome c oxidase. In the later time range (20-40 microseconds), other oxygen-isotope-sensitive Raman bands were observed at 788 and 361 cm-1. Since the 781 cm-1 band exhibited a downshift by 37 cm-1 upon 18O2 substitution, we assigned it to the FeIV=O stretching mode. This band is considered to arise from the ferryl intermediate, but its appearance was much earlier than the corresponding intermediate of bovine cytochrome c oxidase (> 100 microseconds). The 361 cm-1 band showed the 16O/18O isotopic frequency shift of 14 cm-1 similar to the case of bovine cytochrome c oxidase reaction.
Collapse
Affiliation(s)
- S Hirota
- Graduate University for Advanced Studies, Okazaki National Research Institutes, Japan
| | | | | | | | | | | |
Collapse
|
21
|
Babcock GT, Varotsis C. Discrete steps in dioxygen activation--the cytochrome oxidase/O2 reaction. J Bioenerg Biomembr 1993; 25:71-80. [PMID: 8389752 DOI: 10.1007/bf00762849] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The kinetic constraints that are imposed on cytochrome oxidase in its dual function as the terminal oxidant in the respiratory process and as a redox-linked proton pump provide a unique opportunity to investigate the molecular details of biological O2 activation. By using flow/flash techniques, it is possible to visualize individual steps in the O2-binding and reduction process, and results from a number of spectroscopic investigations on the oxidation of reduced cytochrome oxidase by O2 are now available. In this article, we use these results to synthesize a reaction mechanism for O2 activation in the enzyme and to simulate time-concentration profiles for a number of intermediates that have been observed experimentally. Kinetic manifestation of the consequences of coupling exergonic electron transfer to endergonic proton translocation emerge from this analysis. Energetic efficiency in this process apparently requires that potentially toxic intermediate oxidation states of dioxygen accumulate to substantial concentration during the reduction reaction.
Collapse
Affiliation(s)
- G T Babcock
- LASER Laboratory, Michigan State University, East Lansing 48824
| | | |
Collapse
|
22
|
Rousseau DL, Ching Y, Wang J. Proton translocation in cytochrome c oxidase: redox linkage through proximal ligand exchange on cytochrome a3. J Bioenerg Biomembr 1993; 25:165-76. [PMID: 8389749 DOI: 10.1007/bf00762858] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An analysis of resonance Raman scattering data from CO-bound cytochrome c oxidase and from the photodissociated enzyme indicates that histidine may not be coordinated to the iron atom of cytochrome a3 in the CO-bound form of the enzyme. Instead, the data suggest that either a water molecule or a different amino acid residue occupies the proximal ligand position. From these data, it is postulated that ligand exchange on cytochrome a3 can occur under physiological conditions. Studies of mutant hemoglobins have demonstrated that tyrosinate binds preferentially to histidine in the ferric forms of the proteins. In cytochrome c oxidase tyrosine residues are located near the histidine residues recently implicated in coordination to cytochrome a3 (Shapleigh et al., 1992; Hosler et al., this volume). Expanding on these concepts, we propose a model for proton translocation at the O2-binding site based on proximal ligand exchange between tyrosine and histidine on cytochrome a3. The pumping steps take place at the level of the peroxy intermediate and at the level of the ferryl intermediate in the catalytic cycle and are thereby consistent with the recent results of Wilkstrom (1989) who found that proton pumping occurs only at these two steps. It is shown that the model may be readily extended to account for the pumping of two protons at each of the steps.
Collapse
Affiliation(s)
- D L Rousseau
- AT&T Bell Laboratories, Murray Hill, New Jersey 07974
| | | | | |
Collapse
|
23
|
Affiliation(s)
- C Varotsis
- LASER Laboratory, Michigan State University, East Lansing 48824
| | | |
Collapse
|
24
|
The dioxygen cycle. Spectral, kinetic, and thermodynamic characteristics of ferryl and peroxy intermediates observed by reversal of the cytochrome oxidase reaction. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50013-8] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
25
|
Abstract
Many of the membrane-associated oxidases that catalyse respiratory reduction of O2 to water simultaneously couple this exergonic reaction to the translocation of protons across the inner mitochondrial membrane, or the cell membrane in prokaryotes, a process by which metabolic energy is conserved for subsequent synthesis of ATP. The molecular mechanism of O2 reduction and its linkage to H+ translocation are now emerging. The bimetallic haem iron-copper reaction centre in this family of enzymes is the critical structure for catalysis of both these processes.
Collapse
Affiliation(s)
- G T Babcock
- Department of Chemistry, Michigan State University, East Lansing 48824
| | | |
Collapse
|
26
|
Jiang JJ, Bank JF, Zhao WW, Scholes CP. The method of time-resolved spin-probe oximetry: its application to oxygen consumption by cytochrome c oxidase. Biochemistry 1992; 31:1331-9. [PMID: 1310609 DOI: 10.1021/bi00120a008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This work broadens the scope and improves the time resolution of spin-probe oximetry, a technique in which small nitroxide spin probes detect oxygen consumption via change in their relaxation properties [Froncisz, W., Lai, C.-S., & Hyde, J. S. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 411-415]. For rapid oxygen kinetic studies we combined the methodology of spin-probe oximetry with a recently developed loop-gap resonator, stopped-flow EPR system [Hubbell, W. L., Froncisz, W., & Hyde, J. S. (1987) Rev. Sci. Instrum. 58, 1879-1886]. The technique used microliter volumes of reactant solutions. Enzymatic consumption of oxygen by cytochrome c oxidase in the presence of ferrocytochrome c substrate was followed continuously in time under limited-turnover conditions, where the concentration of oxygen consumed often was comparable to or less than the amount of enzyme present. In detecting less than micromolar oxygen concentration changes, we have achieved a time resolution of the order 30 ms when flow is stopped. Oxygen consumption was followed under two different limited-turnover conditions: In the first, the amount of oxygen consumed was limited by available ferrocytochrome c, and the time course of oxygen consumption and its pH dependence were compared with the optically detected ferrocytochrome c consumption. In the second, the oxygen consumed was ultimately limited by the availability of oxygen itself while ferrocytochrome c was regenerated and remained in excess.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- J J Jiang
- Department of Chemistry, State University of New York, Albany 12222
| | | | | | | |
Collapse
|
27
|
Chapter 9 Cytochrome oxidase: notes on structure and mechanism. MOLECULAR MECHANISMS IN BIOENERGETICS 1992. [DOI: 10.1016/s0167-7306(08)60177-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
28
|
|
29
|
Ogura T, Takahashi S, Shinzawa-Itoh K, Yoshikawa S, Kitagawa T. Time-Resolved Resonance Raman Investigation of Cytochrome Oxidase Catalysis: Observation of a New Oxygen-Isotope Sensitive Raman Band. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1991. [DOI: 10.1246/bcsj.64.2901] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
30
|
Observation of the O-O stretching Raman band for cytochrome P-450cam under catalytic conditions. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99216-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
31
|
|