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Baserga F, Dragelj J, Kozuch J, Mohrmann H, Knapp EW, Stripp ST, Heberle J. Quantification of Local Electric Field Changes at the Active Site of Cytochrome c Oxidase by Fourier Transform Infrared Spectroelectrochemical Titrations. Front Chem 2021; 9:669452. [PMID: 33987170 PMCID: PMC8111224 DOI: 10.3389/fchem.2021.669452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/24/2021] [Indexed: 11/30/2022] Open
Abstract
Cytochrome c oxidase (CcO) is a transmembrane protein complex that reduces molecular oxygen to water while translocating protons across the mitochondrial membrane. Changes in the redox states of its cofactors trigger both O2 reduction and vectorial proton transfer, which includes a proton-loading site, yet unidentified. In this work, we exploited carbon monoxide (CO) as a vibrational Stark effect (VSE) probe at the binuclear center of CcO from Rhodobacter sphaeroides. The CO stretching frequency was monitored as a function of the electrical potential, using Fourier transform infrared (FTIR) absorption spectroelectrochemistry. We observed three different redox states (R4CO, R2CO, and O), determined their midpoint potential, and compared the resulting electric field to electrostatic calculations. A change in the local electric field strength of +2.9 MV/cm was derived, which was induced by the redox transition from R4CO to R2CO. We performed potential jump experiments to accumulate the R2CO and R4CO species and studied the FTIR difference spectra in the protein fingerprint region. The comparison of the experimental and computational results reveals that the key glutamic acid residue E286 is protonated in the observed states, and that its hydrogen-bonding environment is disturbed upon the redox transition of heme a3. Our experiments also suggest propionate A of heme a3 changing its protonation state in concert with the redox state of a second cofactor, heme a. This supports the role of propionic acid side chains as part of the proton-loading site.
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Affiliation(s)
- Federico Baserga
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Jovan Dragelj
- Macromolecular Modelling Group, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Modeling of Biomolecular Systems, Technische Universität Berlin, Berlin, Germany
| | - Jacek Kozuch
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Hendrik Mohrmann
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Ernst-Walter Knapp
- Macromolecular Modelling Group, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
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Schultz BJ, Mohrmann H, Lorenz-Fonfria VA, Heberle J. Protein dynamics observed by tunable mid-IR quantum cascade lasers across the time range from 10ns to 1s. Spectrochim Acta A Mol Biomol Spectrosc 2018; 188:666-674. [PMID: 28110813 DOI: 10.1016/j.saa.2017.01.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 12/29/2016] [Accepted: 01/04/2017] [Indexed: 06/06/2023]
Abstract
We have developed a spectrometer based on tunable quantum cascade lasers (QCLs) for recording time-resolved absorption spectra of proteins in the mid-infrared range. We illustrate its performance by recording time-resolved difference spectra of bacteriorhodopsin in the carboxylic range (1800-1700cm-1) and on the CO rebinding reaction of myoglobin (1960-1840cm-1), at a spectral resolution of 1cm-1. The spectrometric setup covers the time range from 4ns to nearly a second with a response time of 10-15ns. Absorption changes as low as 1×10-4 are detected in single-shot experiments at t>1μs, and of 5×10-6 in kinetics obtained after averaging 100 shots. While previous time-resolved IR experiments have mostly been conducted on hydrated films of proteins, we demonstrate here that the brilliance of tunable quantum cascade lasers is superior to perform ns time-resolved experiments even in aqueous solution (H2O).
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Affiliation(s)
- Bernd-Joachim Schultz
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Hendrik Mohrmann
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Victor A Lorenz-Fonfria
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany; Department of Biochemistry and Molecular Biology, Universitat de València, Dr. Moliner 50, 46100 Burjassot, Spain; Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), Universitat de València, Dr. Moliner 50, 46100 Burjassot, Spain
| | - Joachim Heberle
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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Mohrmann H, Dragelj J, Baserga F, Knapp EW, Stripp ST, Heberle J. The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation. Phys Chem Chem Phys 2017. [PMID: 29067359 DOI: 10.1039/c7cp06480b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytochrome c oxidase (CcO) is a membrane protein of the respiratory chain that catalytically reduces molecular oxygen (O2) to water while translocating protons across the membrane. The enzyme hosts two copper and two heme iron moieties (heme a/heme a3). The atomic details of the sequential steps that go along with this redox-driven proton translocation are a matter of debate. Particularly for the reductive phase of CcO that precedes oxygen binding experimental data are scarce. Here, we use CcO under anaerobic conditions where carbon monoxide (CO) is bound to heme a3 which in tandem with CuB forms the binuclear center (BNC). Fourier-transform infrared (FTIR) absorption spectroscopy is combined with electro-chemistry to probe different redox and protonation states populated by variation of the external electrostatic potential. With this approach, the redox behavior of heme a and the BNC could be separated and the corresponding redox potentials were determined. We also infer the protonation of one of the propionate side chains of heme a3 to correlate with the oxidation of heme a. Experimental changes in the local electric field surrounding CO bound to heme a3 are determined by their vibrational Stark effect and agree well with electrostatic computations. The comparison of experimental and computational results indicates that changes of the heme a3/CuB redox state are coupled to proton transfer towards heme a3. The latter supports the role of the heme a3 propionate D as proton loading site.
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Affiliation(s)
- Hendrik Mohrmann
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Jovan Dragelj
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 36A, 14195 Berlin, Germany
| | - Federico Baserga
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Ernst-Walter Knapp
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 36A, 14195 Berlin, Germany
| | - Sven T Stripp
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Joachim Heberle
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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Mohrmann H, Heberle J. Reply to "Comment on 'Transient Conformational Changes of Sensory Rhodopsin II Investigated by Vibrational Stark Effect Probes'". J Phys Chem B 2017; 121:7397-7399. [PMID: 28689420 DOI: 10.1021/acs.jpcb.7b03453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hendrik Mohrmann
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
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Mohrmann H, Dragelj J, Baserga F, Knapp EW, Stripp ST, Heberle J. Retraction: The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation. Phys Chem Chem Phys 2017; 19:32143. [DOI: 10.1039/c7cp90263h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Retraction of ‘The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation’ by Hendrik Mohrmann et al., Phys. Chem. Chem. Phys., 2017, DOI: 10.1039/c7cp06480b.
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Affiliation(s)
- Hendrik Mohrmann
- Experimental Molecular Biophysics
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Jovan Dragelj
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Federico Baserga
- Experimental Molecular Biophysics
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Ernst-Walter Knapp
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Sven T. Stripp
- Experimental Molecular Biophysics
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Joachim Heberle
- Experimental Molecular Biophysics
- Freie Universität Berlin
- 14195 Berlin
- Germany
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Mohrmann H, Kube I, Lórenz-Fonfría VA, Engelhard M, Heberle J. Transient Conformational Changes of Sensory Rhodopsin II Investigated by Vibrational Stark Effect Probes. J Phys Chem B 2016; 120:4383-7. [DOI: 10.1021/acs.jpcb.6b01900] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hendrik Mohrmann
- Department
of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Ines Kube
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Víctor A. Lórenz-Fonfría
- Department
of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Martin Engelhard
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Joachim Heberle
- Department
of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, 14195 Berlin, Germany
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Sezer M, Kielb P, Kuhlmann U, Mohrmann H, Schulz C, Heinrich D, Schlesinger R, Heberle J, Weidinger IM. Surface Enhanced Resonance Raman Spectroscopy Reveals Potential Induced Redox and Conformational Changes of Cytochrome c Oxidase on Electrodes. J Phys Chem B 2015; 119:9586-91. [PMID: 26135359 DOI: 10.1021/acs.jpcb.5b03206] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Immobilization of Cytochrome c oxidase (CcO) on electrodes makes voltage-driven reduction of oxygen to water possible. Efficient catalytic turnover in CcO/electrode systems is, however, often observed at large overpotentials that cannot be rationalized by the redox properties of the enzyme itself. To understand the structural basis for this observation, CcO was electrostatically adsorbed on amino-functionalized Ag electrodes, and the redox transitions of heme a and a3 were monitored via surface enhanced resonance Raman spectroscopy (SERRS) as a function of applied potential. Under completely anaerobic conditions, the reduction of heme a3 could be seen at potentials close to those measured in solution indicating an intact catalytic center. However, in the immobilized state, a new non-native heme species was observed that exhibited a redox potential much more negative than measured for the native hemes. Analysis of the high and low frequency SERR spectra indicated that this new species is formed from heme a upon axial loss of one histidine ligand. It is concluded that the formation of the non-native heme a species alters the potential-dependent electron supply to the catalytic reaction and, thus, can have a impact on the applicability of this enzyme in biofuel cells.
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Affiliation(s)
- Murat Sezer
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Patrycja Kielb
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Uwe Kuhlmann
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Hendrik Mohrmann
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Claudia Schulz
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Dorothea Heinrich
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Ramona Schlesinger
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Joachim Heberle
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Inez M Weidinger
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
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Nebrich E, Mohrmann H. Streulicht- und Temperaturverlauf bei der Kondensation von Äthanoldampf / Pattern of Change of Light Scattering and Temperature during the Condensation of Ethanol Vapor. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/znb-1969-1004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Saturated ethanol vapour in an atmosphere of nitrogen was expanded in a cloud chamber. The condensation arising thereby was shown by light scattering. At the same time the temperature curve occurring after the expansion was measured by means of a resistance thermometer.
Experiments with twenty different expansion ratios (from E=1,083 to E= 1,324) were carried out at room temperature. The expansions were polytropic at n = 1,24.
Supersaturations were obtained at about 1,3 and 1,5 regardless of E and never attained the critical value of 2,1. Nevertheless a condensation was shown every time, although nuclei were not present. The cloud vanished shortly after its appearence, long before the initial temperature could be reached again. The formation as well as start and finish of the evaporation of this “subcritical fog” can be traced exactly in the registered temperature curves. The simultaneous light scatteringand temperature measurement make a stronger interpretation of the temperature curves recorded by STACHORSKA also possible.
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Affiliation(s)
- E. Nebrich
- Physiologisch-Chemisches Institut der Universität Göttingen (Strahlenbiochemisches Labor)
| | - H. Mohrmann
- Physiologisch-Chemisches Institut der Universität Göttingen (Strahlenbiochemisches Labor)
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Jazieh AR, Soora I, Mohrmann H. The reality of mammography utilization in the state of Arkansas. J Ark Med Soc 2000; 97:132-3. [PMID: 12876815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
The Arkansas Mammography Data Collection Project, funded by the Arkansas Department of Health, aimed to determine the mammography screening patterns throughout the state of Arkansas. Data were obtained from 92 mammoraphy centers out of 112 centers (82%). A total of 157,976 mammography data sets were obtained for 148,586 women. Mammography rate was 22.7% for women 40 years and older and 24.1% for women 50 years and older. Mammography rates per county varied from 0.3% to 42.6%. The overall low rate of mammography utilization reflects the need to intensify public health interventions and continuous evaluations of these interventions.
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Mohrmann H, Thier P. The influence of structured visual backgrounds on smooth-pursuit initiation, steady-state pursuit and smooth-pursuit termination. Biol Cybern 1995; 73:83-93. [PMID: 7654852 DOI: 10.1007/bf00199058] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Smooth-pursuit eye movements were recorded in two rhesus monkeys in order to compare the influence of structured visual backgrounds on smooth-pursuit initiation, steady-state pursuit and pursuit termination. Different target trajectories were used in order to study smooth-pursuit initiation and termination. The influence of visual backgrounds on pursuit initiation was characterized by recording ocular responses elicited by step-ramp target displacements starting from straight ahead. Pursuit termination was characterized by analysing the transition from steady-state smooth-pursuit to fixation when a centripetally directed target ramp was terminated by a small target step in the direction of the ramp as soon as the target had come close to the straightahead position. The quantification of steady-state pursuit was based on ocular responses elicited by either paradigm. In accordance with previous work, we found that the onset of smooth-pursuit eye movements was delayed and initial eye acceleration reduced in the presence of a structured visual background. Likewise, mean eye velocity during steady-state pursuit was reduced by structured visual backgrounds. However, neither the latency nor the time course of smooth-pursuit termination was altered when the homogeneous background was replaced by a structured visual background. The lack of sensitivity of pursuit termination to the presence of visual structured backgrounds supports a previous contention that pursuit termination is mediated by a process which is different from the ones mediating smooth-pursuit initiation and steady-state pursuit. The absence of any noticeable effect of structured backgrounds on pursuit termination suggests that at least the fast component of the optokinetic reflex is suppressed during pursuit termination.
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Affiliation(s)
- H Mohrmann
- Sektion für Visuelle Sensomotorik, Neurologische Universitätsklinik, Tübingen, Germany
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