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Sarewicz M, Pintscher S, Pietras R, Borek A, Bujnowicz Ł, Hanke G, Cramer WA, Finazzi G, Osyczka A. Catalytic Reactions and Energy Conservation in the Cytochrome bc1 and b6f Complexes of Energy-Transducing Membranes. Chem Rev 2021; 121:2020-2108. [PMID: 33464892 PMCID: PMC7908018 DOI: 10.1021/acs.chemrev.0c00712] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Indexed: 12/16/2022]
Abstract
This review focuses on key components of respiratory and photosynthetic energy-transduction systems: the cytochrome bc1 and b6f (Cytbc1/b6f) membranous multisubunit homodimeric complexes. These remarkable molecular machines catalyze electron transfer from membranous quinones to water-soluble electron carriers (such as cytochromes c or plastocyanin), coupling electron flow to proton translocation across the energy-transducing membrane and contributing to the generation of a transmembrane electrochemical potential gradient, which powers cellular metabolism in the majority of living organisms. Cytsbc1/b6f share many similarities but also have significant differences. While decades of research have provided extensive knowledge on these enzymes, several important aspects of their molecular mechanisms remain to be elucidated. We summarize a broad range of structural, mechanistic, and physiological aspects required for function of Cytbc1/b6f, combining textbook fundamentals with new intriguing concepts that have emerged from more recent studies. The discussion covers but is not limited to (i) mechanisms of energy-conserving bifurcation of electron pathway and energy-wasting superoxide generation at the quinol oxidation site, (ii) the mechanism by which semiquinone is stabilized at the quinone reduction site, (iii) interactions with substrates and specific inhibitors, (iv) intermonomer electron transfer and the role of a dimeric complex, and (v) higher levels of organization and regulation that involve Cytsbc1/b6f. In addressing these topics, we point out existing uncertainties and controversies, which, as suggested, will drive further research in this field.
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Affiliation(s)
- Marcin Sarewicz
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Sebastian Pintscher
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Rafał Pietras
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Arkadiusz Borek
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Łukasz Bujnowicz
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Guy Hanke
- School
of Biological and Chemical Sciences, Queen
Mary University of London, London E1 4NS, U.K.
| | - William A. Cramer
- Department
of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 United States
| | - Giovanni Finazzi
- Laboratoire
de Physiologie Cellulaire et Végétale, Université Grenoble Alpes, Centre National Recherche Scientifique,
Commissariat Energie Atomique et Energies Alternatives, Institut National
Recherche l’agriculture, l’alimentation et l’environnement, 38054 Grenoble Cedex 9, France
| | - Artur Osyczka
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
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Sakamaki D, Ito A, Tsutsui Y, Seki S. Tetraaza[14]- and Octaaza[18]paracyclophane: Synthesis and Characterization of Their Neutral and Cationic States. J Org Chem 2017; 82:13348-13358. [DOI: 10.1021/acs.joc.7b02437] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Daisuke Sakamaki
- Department of Molecular Engineering,
Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Akihiro Ito
- Department of Molecular Engineering,
Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yusuke Tsutsui
- Department of Molecular Engineering,
Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shu Seki
- Department of Molecular Engineering,
Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
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Klein JH, Sunderland TL, Kaufmann C, Holzapfel M, Schmiedel A, Lambert C. Stepwise versus pseudo-concerted two-electron-transfer in a triarylamine–iridium dipyrrin–naphthalene diimide triad. Phys Chem Chem Phys 2013; 15:16024-30. [DOI: 10.1039/c3cp51981c] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Heckmann A, Lambert C. Organic Mixed-Valence Compounds: A Playground for Electrons and Holes. Angew Chem Int Ed Engl 2011; 51:326-92. [DOI: 10.1002/anie.201100944] [Citation(s) in RCA: 414] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Indexed: 11/05/2022]
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Heckmann A, Lambert C. Organische gemischtvalente Verbindungen: ein Spielplatz für Elektronen und Löcher. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201100944] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Hoekstra RM, Dibrell MM, Weaver MN, Nelsen SF, Zink JI. Three-Chromophore Excited-State Mixed Valence. J Phys Chem A 2008; 113:456-63. [DOI: 10.1021/jp807940h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Ryan M. Hoekstra
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, and Department of Chemistry, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706-1396
| | - Marcelle M. Dibrell
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, and Department of Chemistry, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706-1396
| | - Michael N. Weaver
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, and Department of Chemistry, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706-1396
| | - Stephen F. Nelsen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, and Department of Chemistry, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706-1396
| | - Jeffrey I. Zink
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, and Department of Chemistry, University of Wisconsin, Madison, 1101 University Avenue, Madison, Wisconsin 53706-1396
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7
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Zhao Y, Guo D, Liu Y, He C, Duan C. A mixed-valence (Fe(II))2(Fe(III))2 square for molecular expression of quantum cellular automata. Chem Commun (Camb) 2008:5725-7. [PMID: 19009061 DOI: 10.1039/b811061a] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A di-mixed-valence molecular square (Fe(II))(2)(Fe(III))(2) with two extra mobile electrons (or holes) occupying the opposite corners is achieved via self-assembly as a pure phase with remarkable stability for molecular expression of quantum cellular automata (QCA).
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Affiliation(s)
- Yonggang Zhao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116012, China
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Evans DH. One-Electron and Two-Electron Transfers in Electrochemistry and Homogeneous Solution Reactions. Chem Rev 2008; 108:2113-44. [DOI: 10.1021/cr068066l] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Desai SP, Taff BM, Voldman J. A photopatternable silicone for biological applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:575-581. [PMID: 18081333 DOI: 10.1021/la702827v] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We show the application of a commercially available photopatternable silicone (PPS) that combines the advantageous features of both PDMS and SU-8 to address a critical bioMEMS materials deficiency. Using PPS, we demonstrate the ability to pattern free-standing mechanically isolated elastomeric structures on a silicon substrate: a feat that is challenging to accomplish using soft lithography-based fabrication. PPS readily integrates with many cell-based bioMEMS since it exhibits low autofluorescence and cells easily attach and proliferate on PPS-coated substrates. Because of its inherent photopatternable properties, PPS is compatible with standard microfabrication processes and easily aligns to complex featured substrates on a wafer scale. By leveraging PPS' unique properties, we demonstrate the design of a simple dielectrophoresis-based bioMEMS device for patterning mammalian cells. The key material properties and integration capabilities explored in this work should present new avenues for exploring silicone microstructures for the design and implementation of increasingly complex bioMEMS architectures.
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Affiliation(s)
- Salil P Desai
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Ito A, Inoue S, Hirao Y, Furukawa K, Kato T, Tanaka K. An N-substituted aza[14]metacyclophane tetracation: a spin-quintet tetraradical with four para-phenylenediamine-based semi-quinone moieties. Chem Commun (Camb) 2008:3242-4. [DOI: 10.1039/b805333b] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hirao Y, Ito A, Tanaka K. Intramolecular Charge Transfer in a Star-Shaped Oligoarylamine. J Phys Chem A 2007; 111:2951-6. [PMID: 17385846 DOI: 10.1021/jp068917t] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intervalence (IV) states of the monocationic states of the star-shaped nonaamine (3) and the triamine (2) as the branched unit in 3 have been examined by electrochemical, spectroelectrochemical, and temperature-dependent ESR spectroscopy. The oligoarylamines 2 and 3 were synthesized by using the successive palladium-catalyzed amination reaction. The redox property of 3 was basically the same as that of 2. However, there exist small potential differences between the first three one-electron oxidations for 3, indicating electronic coupling among the peripherally substituted triamine moieties via the central 1,3,5-benzenetriyl bridging unit. The observed ESR spectral pattern for 2+ remained unchanged over the measured temperature range. From the spectral simulation analyses, it was concluded that the unpaired electron in 2+ is fully delocalized over the whole molecule on the ESR time scale. This conclusion was corroborated by comparison of its optical absorption spectrum with TD-DFT-calculated results. In contrast, the peak-to-peak ESR line width (DeltaHPP) of 3+ exhibited temperature dependency. This behavior is ascribed to the thermally activated intramolecular charge transfer (ICT) among the branched three triamine moieties via the central 1,3,5-benzenetriyl bridging unit. From the spectral simulations based on the stochastic Liouville method, the first-order rate constant at each temperature and the parameters of the energy barrier for the ICT in 3+ were successfully determined.
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Affiliation(s)
- Yasukazu Hirao
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
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Amthor S, Lambert C. Dications of Bis-triarylamino-[2.2]paracyclophanes: Evaluation of Excited State Couplings by GMH Analysis. J Phys Chem A 2006; 110:3495-504. [PMID: 16526628 DOI: 10.1021/jp055098o] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we present the absorption properties of a series of bis-triarylamino-[2.2]paracyclophane diradical dications. The localized pi-pi and the charge-transfer (CT) transitions of these dications are explained and analyzed by an exciton coupling model that also considers the photophysical properties of the "monomeric" triarylamine radical cations. Together with AM1-CISD-calculated transition moments, experimental transition moments and transition energies of the bis-triarylamine dications were used to calculate electronic couplings by a generalized Mulliken-Hush (GMH) approach. These couplings are a measure for interactions of the excited mixed-valence CT states. The modification of the diabatic states reveals similarities of the GMH three-level model and the exciton coupling model. Comparison of the two models shows that the transition moment between the excited mixed-valence states mu(ab) of the dimer equals the dipole moment difference Delta of the ground and the excited bridge state of the corresponding monomer.
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Affiliation(s)
- Stephan Amthor
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Nöll G, Avola M. Optically induced electron transfer in anN,N,N′,N′-tetraanisyl-o-phenylenediamine radical cation. J PHYS ORG CHEM 2006. [DOI: 10.1002/poc.1024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Amthor S, Lambert C. [2.2]Paracyclophane-Bridged Mixed-Valence Compounds: Application of a Generalized Mulliken−Hush Three-Level Model. J Phys Chem A 2005; 110:1177-89. [PMID: 16420023 DOI: 10.1021/jp0550309] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A series of [2.2]paracylophane-bridged bis-triarylamine mixed-valence (MV) radical cations were analyzed by a generalized Mulliken-Hush (GMH) three-level model which takes two transitions into account: the intervalence charge transfer (IV-CT) band which is assigned to an optically induced hole transfer (HT) from one triarylamine unit to the second one and a second band associated with a triarylamine radical cation to bridge (in particular, the [2.2]paracyclophane bridge) hole transfer. From the GMH analysis, we conclude that the [2.2]paracyclophane moiety is not the limiting factor which governs the intramolecular charge transfer. AM1-CISD calculations reveal that both through-bond as well as through-space interactions of the [2.2]paracyclophane bridge play an important role for hole transfer processes. These electronic interactions are of course smaller than direct pi-conjugation, but from the order of magnitude of the couplings of the [2.2]paracyclophane MV species, we assume that this bridge is able to mediate significant through-space and through-bond interactions and that the cyclophane bridge acts more like an unsaturated spacer rather than a saturated one. From the exponential dependence of the electronic coupling V between the two triarylamine localized states on the distance r between the two redox centers, we infer that the hole transfer occurs via a superexchange mechanism. Our analysis reveals that even significantly longer pi-conjugated bridges should still mediate significant electronic interactions because the decay constant beta of a series of pi-conjugated MV species is small.
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Affiliation(s)
- Stephan Amthor
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Roos W, Ulmer J, Gräter S, Surrey T, Spatz JP. Microtubule gliding and cross-linked microtubule networks on micropillar interfaces. NANO LETTERS 2005; 5:2630-4. [PMID: 16351227 DOI: 10.1021/nl051865j] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We combined biochemical and topographical patterning to achieve motor-driven microtubule gliding on top of microfabricated pillar arrays with limited and controllable surface interactions of gliding microtubules. Kinesins immobilized on pillar heads pushed microtubules from the top of one micropillar to the next bridging up to 20 mum deep gaps filled with buffer solution. Distances of more than 10 mum were by-passed, and microtubule buckling was occasionally observed. The velocity distributions of microtubules gliding on poly(dimethylsiloxane) (PDMS) pillars, on flat PDMS, and on glass were found to be different, most likely due to topological and/or chemical differences between the substrates. We also used pillar arrays to suspend cross-linked microtubule networks, whose structural characteristics were governed by the topographical characteristics of the pillar pattern. These experiments open new possibilities to study the dynamics and the self-organization of motor/microtubule networks in defined topologically structured environments.
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Affiliation(s)
- Wouter Roos
- Department New Materials & Biosystems, Max-Planck-Institute for Metals Research, Heisenbergstrasse 3, 70569 Stuttgart, Germany
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Osyczka A, Moser CC, Daldal F, Dutton PL. Reversible redox energy coupling in electron transfer chains. Nature 2004; 427:607-12. [PMID: 14961113 DOI: 10.1038/nature02242] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Accepted: 11/14/2003] [Indexed: 11/09/2022]
Abstract
Reversibility is a common theme in respiratory and photosynthetic systems that couple electron transfer with a transmembrane proton gradient driving ATP production. This includes the intensely studied cytochrome bc1, which catalyses electron transfer between quinone and cytochrome c. To understand how efficient reversible energy coupling works, here we have progressively inactivated individual cofactors comprising cytochrome bc1. We have resolved millisecond reversibility in all electron-tunnelling steps and coupled proton exchanges, including charge-separating hydroquinone-quinone catalysis at the Q(o) site, which shows that redox equilibria are relevant on a catalytic timescale. Such rapid reversibility renders popular models based on a semiquinone in Q(o) site catalysis prone to short-circuit failure. Two mechanisms allow reversible function and safely relegate short-circuits to long-distance electron tunnelling on a timescale of seconds: conformational gating of semiquinone for both forward and reverse electron transfer, or concerted two-electron quinone redox chemistry that avoids the semiquinone intermediate altogether.
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Affiliation(s)
- Artur Osyczka
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA
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