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Talaga D, Bremner A, Buffeteau T, Vallée RAL, Lecomte S, Bonhommeau S. Total Internal Reflection Tip-Enhanced Raman Spectroscopy of Cytochrome c. J Phys Chem Lett 2020; 11:3835-3840. [PMID: 32330046 DOI: 10.1021/acs.jpclett.0c00579] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Surface and tip-enhanced Raman spectroscopies in total internal reflection (TIR-SERS and TIR-TERS) are used to characterize the oxidation, spin, and ligation state of cytochrome c (Cc) molecules electrostatically bound on a hydrophilic thiol self-assembled monolayer. TIR-SERS spectra of this model hemoprotein show marker bands typical of the 6cLS ferric state of Cc. The performances of the TIR-TERS technique as a function of the incidence angle are described, showing in particular a significant electromagnetic enhancement of the Raman signal under p-polarized light excitation. TIR-TERS spectra of Cc confirm the 6cLS ferric state assignment deduced from TIR-SERS spectra, thus demonstrating the possibility of probing with nanoscale spatial resolution the 6cLS oxidized form of Cc that is potentially implicated in cell apoptotic processes. The minimal far-field contribution of the sample in TIR-TERS also offers promising perspectives for future nanoscale chemical characterizations of photosensitive biomolecules in complex biological media.
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Affiliation(s)
- David Talaga
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Andrew Bremner
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
- Colorado School of Mines, Golden, Colorado 80401, United States
| | - Thierry Buffeteau
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | | | - Sophie Lecomte
- Univ. Bordeaux, CNRS, CBMN, UMR 5248, F-33600 Pessac, France
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2
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Buhrke D, Hildebrandt P. Probing Structure and Reaction Dynamics of Proteins Using Time-Resolved Resonance Raman Spectroscopy. Chem Rev 2019; 120:3577-3630. [PMID: 31814387 DOI: 10.1021/acs.chemrev.9b00429] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The mechanistic understanding of protein functions requires insight into the structural and reaction dynamics. To elucidate these processes, a variety of experimental approaches are employed. Among them, time-resolved (TR) resonance Raman (RR) is a particularly versatile tool to probe processes of proteins harboring cofactors with electronic transitions in the visible range, such as retinal or heme proteins. TR RR spectroscopy offers the advantage of simultaneously providing molecular structure and kinetic information. The various TR RR spectroscopic methods can cover a wide dynamic range down to the femtosecond time regime and have been employed in monitoring photoinduced reaction cascades, ligand binding and dissociation, electron transfer, enzymatic reactions, and protein un- and refolding. In this account, we review the achievements of TR RR spectroscopy of nearly 50 years of research in this field, which also illustrates how the role of TR RR spectroscopy in molecular life science has changed from the beginning until now. We outline the various methodological approaches and developments and point out current limitations and potential perspectives.
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Affiliation(s)
- David Buhrke
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17, Juni 135, D-10623 Berlin, Germany
| | - Peter Hildebrandt
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17, Juni 135, D-10623 Berlin, Germany
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3
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Clark ML, Ge A, Videla PE, Rudshteyn B, Miller CJ, Song J, Batista VS, Lian T, Kubiak CP. CO2 Reduction Catalysts on Gold Electrode Surfaces Influenced by Large Electric Fields. J Am Chem Soc 2018; 140:17643-17655. [DOI: 10.1021/jacs.8b09852] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Melissa L. Clark
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0358, La Jolla, California 92093, United States
| | - Aimin Ge
- Department of Chemistry, Emory University, 1515 Dickey Drive, Northeast, Atlanta, Georgia 30322, United States
| | - Pablo E. Videla
- Department of Chemistry and Energy Sciences Institute, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Benjamin Rudshteyn
- Department of Chemistry and Energy Sciences Institute, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Christopher J. Miller
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0358, La Jolla, California 92093, United States
| | - Jia Song
- Department of Chemistry, Emory University, 1515 Dickey Drive, Northeast, Atlanta, Georgia 30322, United States
| | - Victor S. Batista
- Department of Chemistry and Energy Sciences Institute, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, 1515 Dickey Drive, Northeast, Atlanta, Georgia 30322, United States
| | - Clifford P. Kubiak
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0358, La Jolla, California 92093, United States
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4
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Götz R, Ly HK, Wrzolek P, Schwalbe M, Weidinger IM. Surface enhanced resonance Raman spectroscopy of iron Hangman complexes on electrodes during electrocatalytic oxygen reduction: advantages and problems of common drycast methods. Dalton Trans 2017; 46:13220-13228. [PMID: 28682383 DOI: 10.1039/c7dt01174a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Drycast methods have been used frequently in recent decades to adsorb a range of synthetic catalysts on electrodes. The uncoordinated multilayers that are formed via this immobilization method can however have a strong impact on the electrocatalytic reaction pathway as slow electron transfer and intermolecular interactions can alter the chemistry of the catalysts on the surface. To gain insight into the structure of Fe porphyrin Hangman catalysts during electrocatalytic oxygen reduction a combination of electrochemistry and surface enhanced resonance Raman spectroscopy (SERRS) was applied. The Hangman complexes were attached to the electrodes via different methods and the influence of the immobilisation technique on oxygen chemistry was studied. In multilayer systems, new intermediates could be identified via potential dependent SERRS that were not present in solution or in monolayer systems under catalytic conditions. A comparison of Raman spectra obtained either via Soret or Q-band excitation showed that the porphyrin symmetry is strongly distorted under reducing conditions, which was interpreted by the transient formation of dimer complexes during catalysis.
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Affiliation(s)
- R Götz
- Fachbereich Chemie und Lebensmittelchemie, Technische Universitaet Dresden, 01062 Dresden, Germany.
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5
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Husband J, Aaron MS, Bains RK, Lewis AR, Warren JJ. Catalytic reduction of dioxygen with modified Thermus thermophilus cytochrome c552. J Inorg Biochem 2016; 157:8-14. [PMID: 26816109 DOI: 10.1016/j.jinorgbio.2016.01.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/23/2015] [Accepted: 01/18/2016] [Indexed: 10/22/2022]
Abstract
Efficient catalysis of the oxygen reduction reaction (ORR) is of central importance to function in fuel cells. Metalloproteins, such as laccase (Cu) or cytochrome c oxidase (Cu/Fe-heme) carry out the 4H(+)/4e(-) reduction quite efficiently, but using large, complex protein frameworks. Smaller heme proteins also can carry out ORR, but less efficiently. To gain greater insight into features that promote efficient ORR, we expressed, characterized, and investigated the electrochemical behavior of six new mutants of cytochrome c552 from Thermus thermophilus: V49S/M69A, V49T/M69A, L29D/V49S/M69A, P27A/P28A/L29D/V49S/M69A, and P27A/P28A/L29D/V49T/M69A. Mutation to V49 causes only minor shifts to Fe(III/II) reduction potentials (E°'), but introduction of Ser provides a hydrogen bond donor that slightly enhances oxygen reduction activity. Mutation of L29 to D induces small shifts in heme optical spectra, but not to E°' (within experimental error). Replacement of P27 and P28 with A in both positions induces a -50 mV shift in E°', again with small changes to the optical spectra. Both the optical spectra and reduction potentials have signatures consistent with peroxidase enzymes. The V49S and V49T mutations have the largest impact of ORR catalysis, suggesting that increased electron density at the Fe site does not improve O2 reduction chemistry.
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Affiliation(s)
- Jonathan Husband
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Michael S Aaron
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Rajneesh K Bains
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Andrew R Lewis
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada.
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6
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Schkolnik G, Salewski J, Millo D, Zebger I, Franzen S, Hildebrandt P. Vibrational stark effect of the electric-field reporter 4-mercaptobenzonitrile as a tool for investigating electrostatics at electrode/SAM/solution interfaces. Int J Mol Sci 2012; 13:7466-7482. [PMID: 22837705 PMCID: PMC3397537 DOI: 10.3390/ijms13067466] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/06/2012] [Accepted: 06/11/2012] [Indexed: 01/24/2023] Open
Abstract
4-mercaptobenzonitrile (MBN) in self-assembled monolayers (SAMs) on Au and Ag electrodes was studied by surface enhanced infrared absorption and Raman spectroscopy, to correlate the nitrile stretching frequency with the local electric field exploiting the vibrational Stark effect (VSE). Using MBN SAMs in different metal/SAM interfaces, we sorted out the main factors controlling the nitrile stretching frequency, which comprise, in addition to external electric fields, the metal-MBN bond, the surface potential, and hydrogen bond interactions. On the basis of the linear relationships between the nitrile stretching and the electrode potential, an electrostatic description of the interfacial potential distribution is presented that allows for determining the electric field strengths on the SAM surface, as well as the effective potential of zero-charge of the SAM-coated metal. Comparing this latter quantity with calculated values derived from literature data, we note a very good agreement for Au/MBN but distinct deviations for Ag/MBN which may reflect either the approximations and simplifications of the model or the uncertainty in reported structural parameters for Ag/MBN. The present electrostatic model consistently explains the electric field strengths for MBN SAMs on Ag and Au as well as for thiophenol and mercaptohexanoic acid SAMs with MBN incorporated as a VSE reporter.
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Affiliation(s)
- Gal Schkolnik
- Technische Universität Berlin, Insitut für Chemie, Sekr. PC14, Straße des 17, Juni 135, Berlin, D-10623, Germany; E-Mails: (G.S.); (J.S.); (D.M.); (I.Z.)
| | - Johannes Salewski
- Technische Universität Berlin, Insitut für Chemie, Sekr. PC14, Straße des 17, Juni 135, Berlin, D-10623, Germany; E-Mails: (G.S.); (J.S.); (D.M.); (I.Z.)
| | - Diego Millo
- Technische Universität Berlin, Insitut für Chemie, Sekr. PC14, Straße des 17, Juni 135, Berlin, D-10623, Germany; E-Mails: (G.S.); (J.S.); (D.M.); (I.Z.)
- Biomolecular Spectroscopy, LaserLaB Amsterdam, Vrije Universiteit Amsterdam, De Boelelaan 1083, Amsterdam, NL-1081 HV, The Netherlands
| | - Ingo Zebger
- Technische Universität Berlin, Insitut für Chemie, Sekr. PC14, Straße des 17, Juni 135, Berlin, D-10623, Germany; E-Mails: (G.S.); (J.S.); (D.M.); (I.Z.)
| | - Stefan Franzen
- Department of Chemistry, North Carolina State University, Box 8204, Raleigh, NC 27695, USA; E-Mail:
| | - Peter Hildebrandt
- Technische Universität Berlin, Insitut für Chemie, Sekr. PC14, Straße des 17, Juni 135, Berlin, D-10623, Germany; E-Mails: (G.S.); (J.S.); (D.M.); (I.Z.)
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7
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Georg S, Kabuss J, Weidinger IM, Murgida DH, Hildebrandt P, Knorr A, Richter M. Distance-dependent electron transfer rate of immobilized redox proteins: a statistical physics approach. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:046101. [PMID: 20481780 DOI: 10.1103/physreve.81.046101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 02/18/2010] [Indexed: 05/29/2023]
Abstract
The electron transfer kinetics of redox proteins adsorbed on metal electrodes coated with self-assembled monolayers (SAMs) of mercaptanes shows an unusual distance-dependence. For thick SAMs, the experimentally measured electron transfer rate constant k{exp} obeys the behavior predicted by Marcus theory [R. A. Marcus and N. Sutin, Biochim. Biophys. Acta 811, 265 (1985)], whereas for thin SAMs, k{exp} remains virtually constant [Z. Q. Feng, J. Chem. Soc., Faraday Trans. 93, 1367 (1997)]. In this work, we present a simple theoretical model system for the redox protein cytochrome c electrostatically bound to a SAM-coated electrode. A statistical average of the electron tunneling rate is calculated by accounting for all possible orientations of the model protein. This approach, which takes into account the electric field dependent orientational distribution, allows for a satisfactory description of the "saturation" regime in the high electric field limit. It further predicts a nonexponential behavior of the average electron transfer processes that may be experimentally checked by extending kinetic experiments to shorter sampling times, i.e., 1/k{exp}. For a comprehensive description of the overall kinetics in the saturation regime at sampling times of the order of <<1/k{exp}, it is essential to consider the dynamics of protein reorientation, which is not implemented in the present model.
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Affiliation(s)
- Sören Georg
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
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8
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Léger C, Bertrand P. Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies. Chem Rev 2008; 108:2379-438. [DOI: 10.1021/cr0680742] [Citation(s) in RCA: 594] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Bonifacio A, Millo D, Keizers PHJ, Boegschoten R, Commandeur JNM, Vermeulen NPE, Gooijer C, van der Zwan G. Active-site structure, binding and redox activity of the heme-thiolate enzyme CYP2D6 immobilized on coated Ag electrodes: a surface-enhanced resonance Raman scattering study. J Biol Inorg Chem 2008; 13:85-96. [PMID: 17899220 PMCID: PMC2099460 DOI: 10.1007/s00775-007-0303-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Accepted: 09/08/2007] [Indexed: 11/28/2022]
Abstract
Surface-enhance resonance Raman scattering spectra of the heme-thiolate enzyme cytochrome P450 2D6 (CYP2D6) adsorbed on Ag electrodes coated with 11-mercaptoundecanoic acid (MUA) were obtained in various experimental conditions. An analysis of these spectra, and a comparison between them and the RR spectra of CYP2D6 in solution, indicated that the enzyme's active site retained its nature of six-coordinated low-spin heme upon immobilization. Moreover, the spectral changes detected in the presence of dextromethorphan (a CYP2D6 substrate) and imidazole (an exogenous heme axial ligand) indicated that the immobilized enzyme also preserved its ability to reversibly bind a substrate and form a heme-imidazole complex. The reversibility of these processes could be easily verified by flowing alternately solutions of the various compounds and the buffer through a home-built spectroelectrochemical flow cell which contained a sample of immobilized protein, without the need to disassemble the cell between consecutive spectral data acquisitions. Despite immobilized CYP2D6 being effectively reduced by a sodium dithionite solution, electrochemical reduction via the Ag electrode was not able to completely reduce the enzyme, and led to its extensive inactivation. This behavior indicated that although the enzyme's ability to exchange electrons is not altered by immobilization per se, MUA-coated electrodes are not suited to perform direct electrochemistry of CYP2D6.
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Affiliation(s)
- Alois Bonifacio
- Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Diego Millo
- Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Peter H. J. Keizers
- Molecular Toxicology, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Roald Boegschoten
- Mechanical Workshop, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Jan N. M. Commandeur
- Molecular Toxicology, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Nico P. E. Vermeulen
- Molecular Toxicology, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Cees Gooijer
- Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
| | - Gert van der Zwan
- Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit Amsterdam, De Boelelaan 1083a, 1081 HV Amsterdam, The Netherlands
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Bernad S, Leygue N, Korri-Youssoufi H, Lecomte S. Kinetics of the electron transfer reaction of Cytochrome c 552 adsorbed on biomimetic electrode studied by time-resolved surface-enhanced resonance Raman spectroscopy and electrochemistry. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:1039-48. [PMID: 17549469 DOI: 10.1007/s00249-007-0173-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 04/23/2007] [Accepted: 04/24/2007] [Indexed: 10/23/2022]
Abstract
Cytochrome c (552) (Cyt-c (552)) and its redox partner ba ( 3 )-oxidase from Thermus thermophilus possess structural differences compared with Horse heart cytochrome c (cyt-c)/cytochrome c oxidase (CcO) system, where the recognition between partners and the electron transfer (ET) process is initiated via electrostatic interactions. We demonstrated in a previous study by surface-enhanced resonance Raman (SERR) spectroscopy that roughened silver electrodes coated with uncharged mixed self-assembled monolayers HS-(CH(2))( n )-CH(3)/HS-(CH(2))( n + 1)-OH 50/50, n = 5, 10 or 15, was a good model to mimic the Cyt-c (552) redox partner. All the adsorbed molecules are well oriented on such biomimetic electrodes and transfer one electron during the redox process. The present work focuses on the kinetic part of the heterogeneous ET process of Cyt-c (552) adsorbed onto electrodes coated with such mixed SAMs of different alkyl chain length. For that purpose, two complementary methods were combined. Firstly cyclic voltammetry shows that the ET between the adsorbed Cyt-c (552) and the biomimetic electrode is direct and reversible. Furthermore, it allows the estimation of both the density surface coverage of adsorbed Cyt-c (552) and the kinetic constants values. Secondly, time-resolved SERR (TR-SERR) spectroscopy showed that the ET process occurs without conformational change of the Cyt-c (552) heme group and allows the determination of kinetic constants. Results show that the kinetic constant values obtained by TR-SERR spectroscopy could be compared to those obtained from cyclic voltammetry. They are estimated at 200, 150 and 40 s(-1) for the ET of Cyt-c (552) adsorbed onto electrodes coated with mixed SAMs HS-(CH(2))( n )-CH(3)/HS-(CH(2))( n + 1)-OH 50/50, n = 5, 10 or 15, respectively.
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Affiliation(s)
- Sophie Bernad
- LADIR, CNRS/UPMC (UMR 7075), 2 rue Henri Dunant, 94320, Thiais, France
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11
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Bernad S, Soulimane T, Mehkalif Z, Lecomte S. Characterization and redox properties of cytochrome c552 from Thermus thermophilus adsorbed on different self-assembled thiol monolayers, used to model the chemical environment of the redox partner. Biopolymers 2006; 81:407-18. [PMID: 16365847 DOI: 10.1002/bip.20432] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The structure of cytochrome c552 (Cyt-c552) from Thermus thermophilus shows many differences to other c-type cytochromes. The rich lysine domain close to the heme does not exist in this cytochrome, allowing us to postulate that the interaction with its redox partner must be different to the cytochrome c/cytochrome c oxidase interaction. We report a study of Cyt-c552 adsorbed on self-assembled monolayers (SAMs) of functionalized alkanethiols used to mimic the chemical properties of its redox partner (ba3-oxydase). Hydrophilic (-COOH), polar (-OH), hydrophobic (-CH3), and mixed (-OH/-CH3) SAMs grafted on roughened silver electrodes were characterized by X-ray photoelectron spectroscopy. Surface enhanced resonance Raman spectroscopy (SERRS) was employed to determine the structure and the redox properties (E degrees and number of transferred electron) of the heme of Cyt-c552 adsorbed on roughened silver electrodes coated by the different SAMs. The surface that most closely models the environment of the ba3-oxidase is a mixed SAM formed by 50% polar [Ag-(CH2)5-CH2OH] and 50% hydrophobic [Ag-(CH2)5-CH3] alkanethiols. Only the native form B1(6cLS) of Cyt-c552 is detected by SERRS when the protein is adsorbed on such a surface that promotes a protein orientation favorable for the electron transfer (number of transferred electron = 1). We shall discuss the differences and similarities of the electron-transfer mechanism of Cyt-c552 compared to cyt-c.
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Affiliation(s)
- Sophie Bernad
- LADIR, CNRS/UPMC (UMR 7075), 2 rue Henri Dunant F-94320 Thiais, France.
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12
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Watanabe J, Morita T, Kimura S. Effects of Dipole Moment, Linkers, and Chromophores at Side Chains on Long-Range Electron Transfer through Helical Peptides. J Phys Chem B 2005; 109:14416-25. [PMID: 16852814 DOI: 10.1021/jp051592g] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Octadecapeptides carrying a ferrocene moiety at the molecular terminal were self-assembled on gold, and long-range electron transfer from the ferrocene moiety to gold was investigated by electrochemical methods. Effects on electron transfer of dipole moment of helical peptides, linkers connecting the peptide to gold, and chromophores introduced into the side chains were discussed. Cyclic voltammetry of the monolayers in an aqueous solution revealed that long-range electron transfer over 40 A occurred along the peptide molecule. Chronoamperometry showed that the long-range electron transfer should be ascribed to a hopping mechanism with use of amide groups as hopping sites. Electron transfer through the long peptide was not significantly accelerated by the dipole moment. However, the linker remarkably affected electron transfer depending on whether it was a methylene chain or a phenylene group, suggesting that local electron transfer between gold and the peptides should be the slowest step to determine the overall rate. Pyrenyl groups introduced into the side chains in the middle of the peptide molecule did not noticeably change electron transfer, probably because pyrenyl groups were too distant to allow direct electron transfer between them. Electrostatic potential profiles across the peptide monolayers were also calculated to explain reasonably the several interesting features in the present peptide systems.
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Affiliation(s)
- Jun Watanabe
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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Bernad S, Oellerich S, Soulimane T, Noinville S, Baron MH, Paternostre M, Lecomte S. Interaction of horse heart and thermus thermophilus type c cytochromes with phospholipid vesicles and hydrophobic surfaces. Biophys J 2005; 86:3863-72. [PMID: 15189883 PMCID: PMC1304288 DOI: 10.1529/biophysj.103.025114] [Citation(s) in RCA: 29] [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
The binding of horse heart cytochrome c (cyt-c) and Thermus thermophilus cytochrome c(552) (cyt-c(552)) to dioleoyl phosphatidylglycerol (DOPG) vesicles was investigated using Fourier transform infrared (FTIR) spectroscopy and turbidity measurements. FTIR spectra revealed that the tertiary structures of both cytochromes became more open when bound to DOPG vesicles, but this was more pronounced for cyt-c. Their secondary structures were unchanged. Turbidity measurements showed important differences in their behavior bound to the negatively charged DOPG vesicles. Both cytochromes caused the liposomes to aggregate and flocculate, but the ways they did so differed. For cyt-c, more than a monolayer was adsorbed onto the liposome surface prior to aggregation due to charge neutralization, whereas cyt c(552) caused aggregation at a protein/lipid ratio well below that required for charge neutralization. Therefore, although cyt-c may cause liposomes to aggregate by electrostatic interaction, cyt-c(552) does not act in this way. FTIR-attenuated total reflection spectroscopy (FTIR-ATR) revealed that cyt-c lost much of its secondary structure when bound to the hydrophobic surface of octadecyltrichlorosilane, whereas cyt-c(552) folds its domains into a beta-structure. This hydrophobic effect may be the key to the difference between the behaviors of the two cytochromes when bound to DOPG vesicles.
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Affiliation(s)
- Sophie Bernad
- Laboratoire de Dynamique, Interactions et Reactivite, CNRS-Universite Paris VI, Thais, France.
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14
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Murgida DH, Hildebrandt P. Electron-transfer processes of cytochrome C at interfaces. New insights by surface-enhanced resonance Raman spectroscopy. Acc Chem Res 2004; 37:854-61. [PMID: 15612675 DOI: 10.1021/ar0400443] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The heme protein cytochrome c acts as an electron carrier at the mitochondrial-membrane interface and thus exerts its function under the influence of strong electric fields. To assess possible consequences of electric fields on the redox processes of cytochrome c, the protein can be immobilized to self-assembled monolayers on electrodes and studied by surface-enhanced resonance Raman spectroscopy. Such model systems may mimic some essential features of biological interfaces including local electric field strengths. It is shown that physiologically relevant electric field strengths can effectively modulate the electron-transfer dynamics and induce conformational transitions.
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Affiliation(s)
- Daniel H Murgida
- Technische Universität Berlin, Institut für Chemie, Max Volmer Laboratorium für Biophysikalische Chemie, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
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15
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Asakura N, Kamachi T, Okura I. Direct monitoring of the electron pool effect of cytochrome c3 by highly sensitive EQCM measurements. J Biol Inorg Chem 2004; 9:1007-16. [PMID: 15517437 DOI: 10.1007/s00775-004-0604-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2004] [Accepted: 09/28/2004] [Indexed: 10/26/2022]
Abstract
Cytochrome c(3) from Desulfovibrio vulgaris has four hemes per molecule, and a redox change at the hemes alters the conformation of the protein, leading to a redox-dependent change in the interaction of cytochrome c(3) with redox partners (an electron acceptor or an electron donor). The redox-dependent change in this interaction was directly monitored by the high-performance electrochemical quartz crystal microbalance (EQCM) technique that has been improved to give high sensitivity in solution. In this method, cytochrome c(3) molecules in solution associate electrostatically with a viologen-immobilized quartz crystal electrode as a monolayer, and redox of the associating cytochrome c(3) is controlled by the immobilized viologen. This technique makes it possible to measure the access of cytochrome c(3) to the electrode or repulsion from the electrode, and hence interconversion between an electrostatic complex and an electron transfer complex on the cytochrome c(3) and the viologen as a mass change accompanying a potential sweep is monitored. In addition, simultaneous measurement of a mass change and a potential step reveals that the cytochrome c(3) stores electrons when the four hemes are reduced (an electron pool effect), that is, the oxidized cytochrome c(3) facilitates acceptance of electrons from the immobilized viologen molecule, but the reduced cytochrome c(3) donates the accepted electrons to the viologen with difficulty.
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Affiliation(s)
- Noriyuki Asakura
- Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, 226-8501, Yokohama, Japan
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Lecomte S, Ricoux R, Mahy JP, Korri-Youssoufi H. Microperoxidase 8 adsorbed on a roughened silver electrode as a monomeric high-spin penta-coordinated species: characterization by SERR spectroscopy and electrochemistry. J Biol Inorg Chem 2004; 9:850-8. [PMID: 15340868 DOI: 10.1007/s00775-004-0586-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2004] [Accepted: 07/26/2004] [Indexed: 10/26/2022]
Abstract
Microperoxidase 8 (MP8), a heme octapeptide obtained by hydrolytic digestion of cytochrome c, was adsorbed at the surface of a roughened silver electrode in order to provide a new supported biomimetic system for hemoproteins. A combination of two techniques was used to study its redox and coordination properties: electrochemistry and surface-enhanced resonance Raman (SERR) spectroscopy. This allowed us to show that MP8 could be adsorbed as a monolayer at the surface of the roughened silver electrode, where it could undergo a reversible electron transfer. Under those conditions, a redox potential of -0.4 V vs. SCE (-0.16 V vs. NHE) was measured for MP8, which was almost identical to that reported for N-acetyl-MP8 in aqueous solution. In addition, whereas MP8 appeared to aggregate in solution, and led to a mixture of high-spin penta-coordinated (5cHS) and low-spin hexa-coordinated (6cLS) iron(III) or iron(II) species, it was recovered almost exclusively as a monomeric high-spin penta-coordinated species at the surface of the electrode, both in the reduced and in the oxidized states. This then allowed a free coordination site on the iron, on the distal face of MP8 accessible to ligands. Accordingly, experiments performed in the presence of potassium cyanide demonstrated that MP8 adsorbed on a silver electrode could be ligated by a sixth CN(-) ligand. Thus there is the possibility of binding several kinds of ligands such as O(2) or H(2)O(2), which will open the way to biocatalysis of oxidation reactions at the surface of an electrode, or ligands such as drugs which will lead to the design of new biosensors for molecules of biological interest.
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Affiliation(s)
- Sophie Lecomte
- LADIR, CNRS/UPMC, 2 rue Henri Dunant, 94320 Thiais, France.
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Bonifacio A, Millo D, Gooijer C, Boegschoten R, van der Zwan G. Linearly Moving Low-Volume Spectroelectrochemical Cell for Microliter-Scale Surface-Enhanced Resonance Raman Spectroscopy of Heme Proteins. Anal Chem 2004; 76:1529-31. [PMID: 14987114 DOI: 10.1021/ac0350615] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Surface-enhanced resonance Raman spectra of cytochrome c on silver electrodes coated with self-assembled monolayers of mercaptopropionic acid were recorded at different potentials using 50 microL of a micromolar solution. For this purpose, a linearly moving, low-volume, small spectroelectrochemical cell was designed and used together with a Raman microprobe. The quality of the spectra obtained is good, and the spectra show essentially the same features reported by other authors using much larger volumes. The cell described in this paper is shown to be useful for studying the spectroelectrochemistry of photosensitive compounds such as heme proteins, which are available only in very small amounts (nanomoles to picomoles).
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Affiliation(s)
- Alois Bonifacio
- Department of Analytical Chemistry and Applied Spectroscopy, Laser Centre, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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18
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Wackerbarth H, Hildebrandt P. Redox and conformational equilibria and dynamics of cytochrome c at high electric fields. Chemphyschem 2003; 4:714-24. [PMID: 12901303 DOI: 10.1002/cphc.200200618] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cytochrome c (Cyt-c) adsorbed in the electrical double layer of the Ag electrode/electrolyte interface has been studied by stationary and time-resolved surface-enhanced resonance Raman spectroscopy to analyse the effect of strong electric fields on structure and reaction equilibria and dynamics of the protein. In the potential range between +0.1 and -0.55 V (versus saturated calomel electrode), the adsorbed Cyt-c forms a potential-dependent reversible equilibrium between the native state B1 and a conformational state B2. The redox potentials of the bis-histidine-coordinated six-coordinated low-spin and five-coordinated high-spin substates of B2 were determined to be -0.425 and -0.385 V, respectively, whereas the additional six-coordinated aquo-histidine-coordinated high-spin substate was found to be redox-inactive. The redox potential for the conformational state B1 was found to be the same as in solution in agreement with the structural identity of the adsorbed B1 and the native Cyt-c. For all three redox-active species, the formal heterogeneous electron transfer rate constants are small and of the same order of magnitude (3-13 s-1), which implies that the rate-limiting step is largely independent of the redox-site structure. These findings, as well as the slow and potential-dependent transitions between the various conformational (sub-)states, can be rationalized in terms of an electric field-induced increase of the activation energy for proton-transfer steps linked to protein structural reorganisation. Further increasing the electric field strength by shifting the electrode potential above +0.1 V leads to irreversible structural changes that are attributed to an unfolding of the polypeptide chain.
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Affiliation(s)
- Hainer Wackerbarth
- Danmarks Tekniske Universitet Biouorganisk Kemi Bygning 207, 2800 Lyngby, Denmark
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19
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Rivas L, Hippler-Mreyen S, Engelhard M, Hildebrandt P. Electric-field dependent decays of two spectroscopically different M-states of photosensory rhodopsin II from Natronobacterium pharaonis. Biophys J 2003; 84:3864-73. [PMID: 12770892 PMCID: PMC1302968 DOI: 10.1016/s0006-3495(03)75114-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2002] [Accepted: 01/22/2003] [Indexed: 10/21/2022] Open
Abstract
Sensory rhodopsin II (NpSRII) from Natronobacterium pharaonis was studied by resonance Raman (RR) spectroscopic techniques. Using gated 413-nm excitation, time-resolved RR measurements of the solubilized photoreceptor were carried out to probe the photocycle intermediates that are formed in the submillisecond time range. For the first time, two M-like intermediates were identified on the basis of their C=C stretching bands at 1568 and 1583 cm(-1), corresponding to the early M(L)(400) state with a lifetime of 30 micro s and the subsequent M(1)(400) state with a lifetime of 2 ms, respectively. The unusually high C=C stretching frequency of M(1)(400) has been attributed to an unprotonated retinal Schiff base in a largely hydrophobic environment, implying that the M(L)(400) --> M(1)(400) transition is associated with protein structural changes in the vicinity of the chromophore binding pocket. Time-resolved surface enhanced resonance Raman experiments of NpSRII electrostatically bound onto a rotating Ag electrode reveal that the photoreceptor runs through the photocycle also in the immobilized state. Surface enhanced resonance Raman spectra are very similar to the RR spectra of the solubilized protein, ruling out adsorption-induced structural changes in the retinal binding pocket. The photocycle kinetics, however, is sensitively affected by the electrode potential such that at 0.0 V (versus Ag/AgCl) the decay times of M(L)(400) and M(1)(400) are drastically slowed down. Upon decreasing the potential to -0.4 V, that corresponds to a decrease of the interfacial potential drop and thus of the electric field strength at the protein binding site, the photocycle kinetics becomes similar to that of NpSRII in solution. The electric-field dependence of the protein structural changes associated with the M-state transitions, which in the present spectroscopic work is revealed on a molecular level, appears to be related to the electric-field control of bacteriorhodopsin's photocycle, which has been shown to be of functional relevance.
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Affiliation(s)
- Laura Rivas
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, P-2781-901 Oeiras, Portugal
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Asakura N, Kamachi T, Okura I. Application of electrochemical quartz crystal microbalance technique to direct monitoring of cytochrome c3 function as the electron pool during intermolecular electron transfer. Anal Biochem 2003; 314:153-7. [PMID: 12633616 DOI: 10.1016/s0003-2697(02)00642-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Noriyuki Asakura
- Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Yokohama, 226-8501, Japan
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21
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Shiryaeva IM, Collman JP, Boulatov R, Sunderland CJ. Nonideal electrochemical behavior of biomimetic iron porphyrins: interfacial potential distribution across multilayer films. Anal Chem 2003; 75:494-502. [PMID: 12585475 DOI: 10.1021/ac025918i] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electrochemical behavior of multilayer films formed by iron porphyrins deposited on an edge plane graphite electrode has been examined under anaerobic conditions. In the scan rate interval (1-250 mV/s) where the electrode reaction is reversible, CV diagrams of these films demonstrate substantial deviations from ideality in broadening and separation of the peaks. A model that describes the observed behavior is proposed by taking into account the potential distribution at the electrode/film interface and the concentration dependence of surface activity coefficients. The peak separation is described in terms of the electric double layer that affects the potential difference driving the electrode reaction. The effective potential difference deviates from the applied value due to the potential distribution across the film. The interfacial potential distribution depends on the ionic concentration inside the film. When different ionic concentrations are assumed for oxidation and reduction, different shifts from the applied potential lead to a hysteresis of the peaks. The peak broadening is modeled by using the lattice theory expression for the surface activity coefficients. The model shows that the midpoint potentials of the redox centers depend on the ionic concentration inside the film. At low ionic concentrations, they are remarkably close to the midpoints of the cytochrome c oxidase heme a3/CuB site.
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Affiliation(s)
- Irina M Shiryaeva
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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22
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Léger C, Jones AK, Albracht SPJ, Armstrong FA. Effect of a Dispersion of Interfacial Electron Transfer Rates on Steady State Catalytic Electron Transport in [NiFe]-hydrogenase and Other Enzymes. J Phys Chem B 2002. [DOI: 10.1021/jp0265687] [Citation(s) in RCA: 217] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christophe Léger
- Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom, and Swammerdam Institute for Life Sciences, Biochemistry, University of Amsterdam, Plantage Muidergracht 12, NL-1018 TV Amsterdam, The Netherlands
| | - Anne K. Jones
- Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom, and Swammerdam Institute for Life Sciences, Biochemistry, University of Amsterdam, Plantage Muidergracht 12, NL-1018 TV Amsterdam, The Netherlands
| | - Simon P. J. Albracht
- Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom, and Swammerdam Institute for Life Sciences, Biochemistry, University of Amsterdam, Plantage Muidergracht 12, NL-1018 TV Amsterdam, The Netherlands
| | - Fraser A. Armstrong
- Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom, and Swammerdam Institute for Life Sciences, Biochemistry, University of Amsterdam, Plantage Muidergracht 12, NL-1018 TV Amsterdam, The Netherlands
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On the calculation of rate constants by approximating the Fermi–Dirac distribution with a step function. J Electroanal Chem (Lausanne) 2002. [DOI: 10.1016/s0022-0728(01)00688-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
Cytochrome c (Cyt-c) was electrostatically bound to self-assembled monolayers (SAM) on an Ag electrode, which are formed by omega-carboxyl alkanethiols of different chain lengths (C(x)). The dynamics of the electron-transfer (ET) reaction of the adsorbed heme protein, initiated by a rapid potential jump to the redox potential, was monitored by time-resolved surface enhanced resonance Raman (SERR) spectroscopy. Under conditions of the present experiments, only the reduced and oxidized forms of the native protein state contribute to the SERR spectra. Thus, the data obtained from the spectra were described by a one-step relaxation process yielding the rate constants of the ET between the adsorbed Cyt-c and the electrode for a driving force of zero electronvolts. For C(16)- and C(11)-SAMs, the respective rate constants of 0.073 and 43 s(-1) correspond to an exponential distance dependence of the ET (beta = 1.28 A(-1)), very similar to that observed for long-range intramolecular ET of redox proteins. Upon further decreasing the chain length, the rate constant only slightly increases to 134 s(-1) at C(6)- and remains essentially unchanged at C(3)- and C(2)-SAMs. The onset of the nonexponential distance dependence is paralleled by a kinetic H/D effect that increases from 1.2 at C(6)- to 4.0 at C(2)-coatings, indicating a coupling of the redox reaction with proton-transfer (PT) steps. These PT processes are attributed to the rearrangement of the hydrogen-bonding network of the protein associated with the transition between the oxidized and reduced state of Cyt-c. Since this unusual kinetic behavior has not been observed for electron-transferring proteins in solution, it is concluded that at the Ag/SAM interface the energy barrier for the PT processes of the adsorbed Cyt-c is raised by the electric field. This effect increases upon reducing the distance to the electrode, until nuclear tunneling becomes the rate-limiting step of the redox process. The electric field dependence of the proton-coupled ET may represent a possible mechanism for controlling biological redox reactions via changes of the transmembrane potential.
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Affiliation(s)
- D H Murgida
- Contribution from the Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
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Wackerbarth H, Murgida D, Oellerich S, Döpner S, Rivas L, Hildebrandt P. Dynamics and mechanism of the electron transfer process of cytochrome c probed by resonance Raman and surface enhanced resonance Raman spectroscopy. J Mol Struct 2001. [DOI: 10.1016/s0022-2860(00)00808-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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26
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Murgida D, Hildebrandt P. The heterogeneous electron transfer of cytochrome c adsorbed on Ag electrodes coated with ω-carboxyl alkanethiols. A surface enhanced resonance Raman spectroscopic study. J Mol Struct 2001. [DOI: 10.1016/s0022-2860(00)00781-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Lecomte S, Hilleriteau C, Forgerit JP, Revault M, Baron MH, Hildebrandt P, Soulimane T. Structural Changes of Cytochromec552 fromThermus thermophilus Adsorbed on Anionic and Hydrophobic Surfaces Probed by FTIR and 2D-FTIR Spectroscopy. Chembiochem 2001. [DOI: 10.1002/1439-7633(20010302)2:3<180::aid-cbic180>3.0.co;2-b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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Murgida DH, Hildebrandt P. Elektronentransferdynamik von adsorbiertem Cytochromc auf selbstorganisierten Monoschichten - eine Untersuchung mit zeitaufgelöster oberflächenverstärkter Resonanz-Raman-Spektroskopie. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20010216)113:4<751::aid-ange7510>3.0.co;2-g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Murgida DH, Hildebrandt P. Active-Site Structure and Dynamics of Cytochrome c Immobilized on Self-Assembled Monolayers-A Time-Resolved Surface Enhanced Resonance Raman Spectroscopic Study This work was supported by the Deutsche Forschungsgemeinschaft, the Volkswagenstiftung, and the Alexander-von-Humboldt Foundation. Angew Chem Int Ed Engl 2001; 40:728-731. [PMID: 11241605 DOI: 10.1002/1521-3773(20010216)40:4<728::aid-anie7280>3.0.co;2-p] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Daniel H. Murgida
- Max-Planck-Institut für Strahlenchemie Stiftstrasse 34-36, 45470 Mülheim an der Ruhr (Germany)
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30
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Murgida DH, Hildebrandt P. Heterogeneous Electron Transfer of Cytochrome c on Coated Silver Electrodes. Electric Field Effects on Structure and Redox Potential. J Phys Chem B 2001. [DOI: 10.1021/jp003742n] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel H. Murgida
- Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Peter Hildebrandt
- Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
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31
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Dick LA, Haes AJ, Van Duyne RP. Distance and Orientation Dependence of Heterogeneous Electron Transfer: A Surface-Enhanced Resonance Raman Scattering Study of Cytochrome c Bound to Carboxylic Acid Terminated Alkanethiols Adsorbed on Silver Electrodes. J Phys Chem B 2000. [DOI: 10.1021/jp0029717] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lisa A. Dick
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113
| | - Amanda J. Haes
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113
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