1
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Yano J, Kern J, Yachandra VK. Structure Function Studies of Photosystem II Using X-Ray Free Electron Lasers. Annu Rev Biophys 2024; 53:343-365. [PMID: 39013027 DOI: 10.1146/annurev-biophys-071723-102519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
The structure and mechanism of the water-oxidation chemistry that occurs in photosystem II have been subjects of great interest. The advent of X-ray free electron lasers allowed the determination of structures of the stable intermediate states and of steps in the transitions between these intermediate states, bringing a new perspective to this field. The room-temperature structures collected as the photosynthetic water oxidation reaction proceeds in real time have provided important novel insights into the structural changes and the mechanism of the water oxidation reaction. The time-resolved measurements have also given us a view of how this reaction-which involves multielectron, multiproton processes-is facilitated by the interaction of the ligands and the protein residues in the oxygen-evolving complex. These structures have also provided a picture of the dynamics occurring in the channels within photosystem II that are involved in the transport of the substrate water to the catalytic center and protons to the bulk.
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Affiliation(s)
- Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA; , ,
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA; , ,
| | - Vittal K Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA; , ,
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2
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Liu J, Yang KR, Long Z, Armstrong WH, Brudvig GW, Batista VS. Water Ligands Regulate the Redox Leveling Mechanism of the Oxygen-Evolving Complex of the Photosystem II. J Am Chem Soc 2024; 146:15986-15999. [PMID: 38833517 DOI: 10.1021/jacs.4c02926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Understanding how water ligands regulate the conformational changes and functionality of the oxygen-evolving complex (OEC) in photosystem II (PSII) throughout the catalytic cycle of oxygen evolution remains a highly intriguing and unresolved challenge. In this study, we investigate the effect of water insertion (WI) on the redox state of the OEC by using the molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) hybrid methods. We find that water binding significantly reduces the free energy change for proton-coupled electron transfer (PCET) from Mn to YZ•, underscoring the important regulatory role of water binding, which is essential for enabling the OEC redox-leveling mechanism along the catalytic cycle. We propose a water binding mechanism in which WI is thermodynamically favored by the closed-cubane form of the OEC, with water delivery mediated by Ca2+ ligand exchange. Isomerization from the closed- to open-cubane conformation at three post-WI states highlights the importance of the location of the MnIII center in the OEC and the orientation of its Jahn-Teller axis to conformational changes of the OEC, which might be critical for the formation of the O-O bond. These findings reveal a complex interplay between conformational changes in the OEC and the ligand environment during the activation of the OEC by YZ•. Analogous regulatory effects due to water ligand binding are expected to be important for a wide range of catalysts activated by redox state transitions in aqueous environments.
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Affiliation(s)
- Jinchan Liu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Ke R Yang
- Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, China
| | - Zhuoran Long
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - William H Armstrong
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Gary W Brudvig
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, United States
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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3
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Barchenko M, O’Malley PJ. A Reappraisal of the S2 State of Nature's Water Oxidizing Complex in Its Low and High Spin Forms. J Phys Chem Lett 2024; 15:5883-5886. [PMID: 38804862 PMCID: PMC11163464 DOI: 10.1021/acs.jpclett.4c00997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 05/29/2024]
Abstract
Density functional theory calculated 14N hyperfine couplings are obtained for the Mn1 ligated π-N of residue His332 of the photosystem 2 water oxidizing complex. An open cubane, O4H, model closely matches the experimental coupling obtained for the high spin S = 5/2 form of the S2 state, supporting an open cubane structure for this state. We also investigate the unusual geometric features for the S2 state obtained by X-ray free electron laser structure determinations and rationalize it as an equilibrium occurring at room temperature between W1/O4 deprotonated and protonated forms of the open cubane structure.
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Affiliation(s)
- Maxim Barchenko
- Department of Chemistry,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, United
Kingdom
| | - Patrick J. O’Malley
- Department of Chemistry,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, United
Kingdom
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4
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Chernev P, Aydin AO, Messinger J. On the simulation and interpretation of substrate-water exchange experiments in photosynthetic water oxidation. PHOTOSYNTHESIS RESEARCH 2024:10.1007/s11120-024-01084-8. [PMID: 38512410 DOI: 10.1007/s11120-024-01084-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 02/01/2024] [Indexed: 03/23/2024]
Abstract
Water oxidation by photosystem II (PSII) sustains most life on Earth, but the molecular mechanism of this unique process remains controversial. The ongoing identification of the binding sites and modes of the two water-derived substrate oxygens ('substrate waters') in the various intermediates (Si states, i = 0, 1, 2, 3, 4) that the water-splitting tetra-manganese calcium penta-oxygen (Mn4CaO5) cluster attains during the reaction cycle provides central information towards resolving the unique chemistry of biological water oxidation. Mass spectrometric measurements of single- and double-labeled dioxygen species after various incubation times of PSII with H218O provide insight into the substrate binding modes and sites via determination of exchange rates. Such experiments have revealed that the two substrate waters exchange with different rates that vary independently with the Si state and are hence referred to as the fast (Wf) and the slow (WS) substrate waters. New insight for the molecular interpretation of these rates arises from our recent finding that in the S2 state, under special experimental conditions, two different rates of WS exchange are observed that appear to correlate with the high spin and low spin conformations of the Mn4CaO5 cluster. Here, we reexamine and unite various proposed methods for extracting and assigning rate constants from this recent data set. The analysis results in a molecular model for substrate-water binding and exchange that reconciles the expected non-exchangeability of the central oxo bridge O5 when located between two Mn(IV) ions with the experimental and theoretical assignment of O5 as WS in all S states. The analysis also excludes other published proposals for explaining the water exchange kinetics.
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Affiliation(s)
- Petko Chernev
- Molecular Biomimetics, Department of Chemistry - Ångström Laboratory, 75120, Uppsala, Sweden
| | - A Orkun Aydin
- Molecular Biomimetics, Department of Chemistry - Ångström Laboratory, 75120, Uppsala, Sweden
| | - Johannes Messinger
- Molecular Biomimetics, Department of Chemistry - Ångström Laboratory, 75120, Uppsala, Sweden.
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5
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Drosou M, Pantazis DA. Comprehensive Evaluation of Models for Ammonia Binding to the Oxygen Evolving Complex of Photosystem II. J Phys Chem B 2024; 128:1333-1349. [PMID: 38299511 PMCID: PMC10875651 DOI: 10.1021/acs.jpcb.3c06304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/08/2024] [Accepted: 01/17/2024] [Indexed: 02/02/2024]
Abstract
The identity and insertion pathway of the substrate oxygen atoms that are coupled to dioxygen by the oxygen-evolving complex (OEC) remains a central question toward understanding Nature's water oxidation mechanism. In several studies, ammonia has been used as a small "water analogue" to elucidate the pathway of substrate access to the OEC and to aid in determining which of the oxygen ligands of the tetramanganese cluster are substrates for O-O bond formation. On the basis of structural and spectroscopic investigations, five first-sphere binding modes of ammonia have been suggested, involving either substitution of an existing H2O/OH-/O2- group or addition as an extra ligand to a metal ion of the Mn4CaO5 cluster. Some of these modes, specifically the ones involving substitution, have already been subject to spectroscopy-oriented quantum chemical investigations, whereas more recent suggestions that postulate the addition of ammonia have not been examined so far with quantum chemistry for their agreement with spectroscopic data. Herein, we use a common structural framework and theoretical methodology to evaluate structural models of the OEC that represent all proposed modes of first-sphere ammonia interaction with the OEC in its S2 state. Criteria include energetic, magnetic, kinetic, and spectroscopic properties compared against available experimental EPR, ENDOR, ESEEM, and EDNMR data. Our results show that models featuring ammonia replacing one of the two terminal water ligands on Mn4 align best with experimental data, while they definitively exclude substitution of a bridging μ-oxo ligand as well as incorporation of ammonia as a sixth ligand on Mn1 or Mn4.
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Affiliation(s)
- Maria Drosou
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
- Inorganic
Chemistry Laboratory, National and Kapodistrian
University of Athens, Panepistimiopolis, Zografou 15771, Greece
| | - Dimitrios A. Pantazis
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
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6
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Shiau AA, Lee HB, Oyala PH, Agapie T. Coordination Number in High-Spin-Low-Spin Equilibrium in Cluster Models of the S 2 State of the Oxygen Evolving Complex. J Am Chem Soc 2023; 145:14592-14598. [PMID: 37366634 PMCID: PMC10575483 DOI: 10.1021/jacs.3c04464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
The S2 state of the Oxygen Evolving Complex (OEC) of Photosystem II (PSII) shows high-spin (HS) and low-spin (LS) EPR signals attributed to distinct structures based on computation. Five-coordinate MnIII centers are proposed in these species but are absent in available spectroscopic model complexes. Herein, we report the synthesis, crystal structure, electrochemistry, SQUID magnetometry, and EPR spectroscopy of a MnIIIMnIV3O4 cuboidal complex featuring five-coordinate MnIII. This cluster displays a spin ground state of S = 5/2, while conversion to a six-coordinate Mn upon treatment with water results in a spin state change to S = 1/2. These results demonstrate that coordination number, without dramatic changes within the Mn4O4 core, has a substantial effect on spectroscopy.
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Affiliation(s)
- Angela A Shiau
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd MC 127-72, Pasadena, California 91125, United States
| | - Heui Beom Lee
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd MC 127-72, Pasadena, California 91125, United States
| | - Paul H Oyala
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd MC 127-72, Pasadena, California 91125, United States
| | - Theodor Agapie
- Department of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E California Blvd MC 127-72, Pasadena, California 91125, United States
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7
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Shevela D, Kern JF, Govindjee G, Messinger J. Solar energy conversion by photosystem II: principles and structures. PHOTOSYNTHESIS RESEARCH 2023; 156:279-307. [PMID: 36826741 PMCID: PMC10203033 DOI: 10.1007/s11120-022-00991-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 12/01/2022] [Indexed: 05/23/2023]
Abstract
Photosynthetic water oxidation by Photosystem II (PSII) is a fascinating process because it sustains life on Earth and serves as a blue print for scalable synthetic catalysts required for renewable energy applications. The biophysical, computational, and structural description of this process, which started more than 50 years ago, has made tremendous progress over the past two decades, with its high-resolution crystal structures being available not only of the dark-stable state of PSII, but of all the semi-stable reaction intermediates and even some transient states. Here, we summarize the current knowledge on PSII with emphasis on the basic principles that govern the conversion of light energy to chemical energy in PSII, as well as on the illustration of the molecular structures that enable these reactions. The important remaining questions regarding the mechanism of biological water oxidation are highlighted, and one possible pathway for this fundamental reaction is described at a molecular level.
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Affiliation(s)
- Dmitry Shevela
- Department of Chemistry, Chemical Biological Centre, Umeå University, 90187, Umeå, Sweden.
| | - Jan F Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Govindjee Govindjee
- Department of Plant Biology, Department of Biochemistry and Center of Biophysics & Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Johannes Messinger
- Department of Chemistry, Chemical Biological Centre, Umeå University, 90187, Umeå, Sweden.
- Molecular Biomimetics, Department of Chemistry - Ångström, Uppsala University, 75120, Uppsala, Sweden.
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8
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Drosou M, Comas-Vilà G, Neese F, Salvador P, Pantazis DA. Does Serial Femtosecond Crystallography Depict State-Specific Catalytic Intermediates of the Oxygen-Evolving Complex? J Am Chem Soc 2023; 145:10604-10621. [PMID: 37137865 DOI: 10.1021/jacs.3c00489] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Recent advances in serial femtosecond crystallography (SFX) of photosystem II (PSII), enabled by X-ray free electron lasers (XFEL), provided the first geometric models of distinct intermediates in the catalytic S-state cycle of the oxygen-evolving complex (OEC). These models are obtained by flash-advancing the OEC from the dark-stable state (S1) to more oxidized intermediates (S2 and S3), eventually cycling back to the most reduced S0. However, the interpretation of these models is controversial because geometric parameters within the Mn4CaO5 cluster of the OEC do not exactly match those expected from coordination chemistry for the spectroscopically verified manganese oxidation states of the distinct S-state intermediates. Here we focus on the first catalytic transition, S1 → S2, which represents a one-electron oxidation of the OEC. Combining geometric and electronic structure criteria, including a novel effective oxidation state approach, we analyze existing 1-flash (1F) SFX-XFEL crystallographic models that should depict the S2 state of the OEC. We show that the 1F/S2 equivalence is not obvious, because the Mn oxidation states and total unpaired electron counts encoded in these models are not fully consistent with those of a pure S2 state and with the nature of the S1 → S2 transition. Furthermore, the oxidation state definition in two-flashed (2F) structural models is practically impossible to elucidate. Our results advise caution in the extraction of electronic structure information solely from the literal interpretation of crystallographic models and call for re-evaluation of structural and mechanistic interpretations that presume exact correspondence of such models to specific catalytic intermediates of the OEC.
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Affiliation(s)
- Maria Drosou
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Gerard Comas-Vilà
- Institute of Computational Chemistry and Catalysis, Chemistry Department, University of Girona, Montilivi Campus, Girona, Catalonia 17003, Spain
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Pedro Salvador
- Institute of Computational Chemistry and Catalysis, Chemistry Department, University of Girona, Montilivi Campus, Girona, Catalonia 17003, Spain
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
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9
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Guo Y, Messinger J, Kloo L, Sun L. Alternative Mechanism for O 2 Formation in Natural Photosynthesis via Nucleophilic Oxo-Oxo Coupling. J Am Chem Soc 2023; 145:4129-4141. [PMID: 36763485 DOI: 10.1021/jacs.2c12174] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
O2 formation in photosystem II (PSII) is a vital event on Earth, but the exact mechanism remains unclear. The presently prevailing theoretical model is "radical coupling" (RC) involving a Mn(IV)-oxyl unit in an "open-cubane" Mn4CaO6 cluster, which is supported experimentally by the S3 state of cyanobacterial PSII featuring an additional Mn-bound oxygenic ligand. However, it was recently proposed that the major structural form of the S3 state of higher plants lacks this extra ligand, and that the resulting S4 state would feature instead a penta-coordinate dangler Mn(V)=oxo, covalently linked to a "closed-cubane" Mn3CaO4 cluster. For this proposal, we explore here a large number of possible pathways of O-O bond formation and demonstrate that the "nucleophilic oxo-oxo coupling" (NOOC) between Mn(V)=oxo and μ3-oxo is the only eligible mechanism in such a system. The reaction is facilitated by a specific conformation of the cluster and concomitant water binding, which is delayed compared to the RC mechanism. An energetically feasible process is described starting from the valid S4 state through the sequential formation of peroxide and superoxide, followed by O2 release and a second water insertion. The newly found mechanism is consistent with available experimental thermodynamic and kinetic data and thus a viable alternative pathway for O2 formation in natural photosynthesis, in particular for higher plants.
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Affiliation(s)
- Yu Guo
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Johannes Messinger
- Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), Umeå SE-90187, Sweden
- Molecular Biomimetics, Department of Chemistry─Ångström Laboratory, Uppsala University, Uppsala SE-75120, Sweden
| | - Lars Kloo
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-10044, Sweden
| | - Licheng Sun
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
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10
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Lubitz W, Pantazis DA, Cox N. Water oxidation in oxygenic photosynthesis studied by magnetic resonance techniques. FEBS Lett 2023; 597:6-29. [PMID: 36409002 DOI: 10.1002/1873-3468.14543] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/23/2022]
Abstract
The understanding of light-induced biological water oxidation in oxygenic photosynthesis is of great importance both for biology and (bio)technological applications. The chemically difficult multistep reaction takes place at a unique protein-bound tetra-manganese/calcium cluster in photosystem II whose structure has been elucidated by X-ray crystallography (Umena et al. Nature 2011, 473, 55). The cluster moves through several intermediate states in the catalytic cycle. A detailed understanding of these intermediates requires information about the spatial and electronic structure of the Mn4 Ca complex; the latter is only available from spectroscopic techniques. Here, the important role of Electron Paramagnetic Resonance (EPR) and related double resonance techniques (ENDOR, EDNMR), complemented by quantum chemical calculations, is described. This has led to the elucidation of the cluster's redox and protonation states, the valence and spin states of the manganese ions and the interactions between them, and contributed substantially to the understanding of the role of the protein surrounding, as well as the binding and processing of the substrate water molecules, the O-O bond formation and dioxygen release. Based on these data, models for the water oxidation cycle are developed.
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Affiliation(s)
- Wolfgang Lubitz
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim/Ruhr, Germany
| | | | - Nicholas Cox
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
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11
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Isobe H, Shoji M, Suzuki T, Shen JR, Yamaguchi K. Roles of the Flexible Primary Coordination Sphere of the Mn 4CaO x Cluster: What Are the Immediate Decay Products of the S3 State? J Phys Chem B 2022; 126:7212-7228. [DOI: 10.1021/acs.jpcb.2c02596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hiroshi Isobe
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Mitsuo Shoji
- Center for Computational Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - Takayoshi Suzuki
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Kizashi Yamaguchi
- Institute for NanoScience Design, Osaka University, Toyonaka, Osaka 560-0043, Japan
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12
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Guo Y, Messinger J, Kloo L, Sun L. Reversible Structural Isomerization of Nature's Water Oxidation Catalyst Prior to O-O Bond Formation. J Am Chem Soc 2022; 144:11736-11747. [PMID: 35748306 PMCID: PMC9264352 DOI: 10.1021/jacs.2c03528] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
Photosynthetic water
oxidation is catalyzed by a manganese–calcium
oxide cluster, which experiences five “S-states” during
a light-driven reaction cycle. The unique “distorted chair”-like
geometry of the Mn4CaO5(6) cluster shows structural
flexibility that has been frequently proposed to involve “open”
and “closed”-cubane forms from the S1 to
S3 states. The isomers are interconvertible in the S1 and S2 states, while in the S3 state,
the open-cubane structure is observed to dominate inThermosynechococcus elongatus (cyanobacteria) samples.
In this work, using density functional theory calculations, we go
beyond the S3+Yz state to the S3nYz• → S4+Yz step, and report for the first time
that the reversible isomerism, which is suppressed in the S3+Yz state, is fully recovered
in the ensuing S3nYz• state due to the proton release
from a manganese-bound water ligand. The altered coordination strength
of the manganese–ligand facilitates formation of the closed-cubane
form, in a dynamic equilibrium with the open-cubane form. This tautomerism
immediately preceding dioxygen formation may constitute the rate limiting
step for O2 formation, and exert a significant influence
on the water oxidation mechanism in photosystem II.
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Affiliation(s)
- Yu Guo
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
| | - Johannes Messinger
- Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), SE-90187 Umeå, Sweden.,Molecular Biomimetics, Department of Chemistry─Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
| | - Lars Kloo
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Licheng Sun
- Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, China.,Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, China
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13
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Flesher DA, Liu J, Wiwczar JM, Reiss K, Yang KR, Wang J, Askerka M, Gisriel CJ, Batista VS, Brudvig GW. Glycerol binding at the narrow channel of photosystem II stabilizes the low-spin S 2 state of the oxygen-evolving complex. PHOTOSYNTHESIS RESEARCH 2022; 152:167-175. [PMID: 35322325 PMCID: PMC9427693 DOI: 10.1007/s11120-022-00911-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 03/02/2022] [Indexed: 05/11/2023]
Abstract
The oxygen-evolving complex (OEC) of photosystem II (PSII) cycles through redox intermediate states Si (i = 0-4) during the photochemical oxidation of water. The S2 state involves an equilibrium of two isomers including the low-spin S2 (LS-S2) state with its characteristic electron paramagnetic resonance (EPR) multiline signal centered at g = 2.0, and a high-spin S2 (HS-S2) state with its g = 4.1 EPR signal. The relative intensities of the two EPR signals change under experimental conditions that shift the HS-S2/LS-S2 state equilibrium. Here, we analyze the effect of glycerol on the relative stability of the LS-S2 and HS-S2 states when bound at the narrow channel of PSII, as reported in an X-ray crystal structure of cyanobacterial PSII. Our quantum mechanics/molecular mechanics (QM/MM) hybrid models of cyanobacterial PSII show that the glycerol molecule perturbs the hydrogen-bond network in the narrow channel, increasing the pKa of D1-Asp61 and stabilizing the LS-S2 state relative to the HS-S2 state. The reported results are consistent with the absence of the HS-S2 state EPR signal in native cyanobacterial PSII EPR spectra and suggest that the narrow water channel hydrogen-bond network regulates the relative stability of OEC catalytic intermediates during water oxidation.
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Affiliation(s)
- David A Flesher
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Jinchan Liu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Jessica M Wiwczar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Krystle Reiss
- Department of Chemistry, Yale University, New Haven, CT, 05620, USA
| | - Ke R Yang
- Department of Chemistry, Yale University, New Haven, CT, 05620, USA
| | - Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Mikhail Askerka
- Department of Chemistry, Yale University, New Haven, CT, 05620, USA
| | | | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, CT, 05620, USA
| | - Gary W Brudvig
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
- Department of Chemistry, Yale University, New Haven, CT, 05620, USA.
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14
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Relative energies among S3 intermediates in the photosystem II revealed by DLPNO coupled cluster and hybrid DFT calculations. Possible pathways of water insertion in the S2 to S3 transition. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139439] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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15
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Debus RJ. Alteration of the O 2-Producing Mn 4Ca Cluster in Photosystem II by the Mutation of a Metal Ligand. Biochemistry 2021; 60:3841-3855. [PMID: 34898175 DOI: 10.1021/acs.biochem.1c00504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The O2-evolving Mn4Ca cluster in photosystem II (PSII) is arranged as a distorted Mn3Ca cube that is linked to a fourth Mn ion (denoted as Mn4) by two oxo bridges. The Mn4 and Ca ions are bridged by residue D1-D170. This is also the only residue known to participate in the high-affinity Mn(II) site that participates in the light-driven assembly of the Mn4Ca cluster. In this study, we use Fourier transform infrared difference spectroscopy to characterize the impact of the D1-D170E mutation. On the basis of analyses of carboxylate and carbonyl stretching modes and the O-H stretching modes of hydrogen-bonded water molecules, we show that this mutation alters the extensive network of hydrogen bonds that surrounds the Mn4Ca cluster in the same manner as that of many other mutations. It also alters the equilibrium between conformers of the Mn4Ca cluster in the dark-stable S1 state so that a high-spin form of the S2 state is produced during the S1-to-S2 transition instead of the low-spin form that gives rise to the S2 state multiline electron paramagnetic resonance signal. The mutation may also change the coordination mode of the carboxylate group at position 170 to unidentate ligation of Mn4. This is the first mutation of a metal ligand in PSII that substantially impacts the spectroscopic signatures of the Mn4Ca cluster without substantially eliminating O2 evolution. The results have significant implications for our understanding of the roles of alternate active/inactive conformers of the Mn4Ca cluster in the mechanism of O2 formation.
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Affiliation(s)
- Richard J Debus
- Department of Biochemistry, University of California, Riverside, California 92521, United States
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16
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de Lichtenberg C, Kim CJ, Chernev P, Debus RJ, Messinger J. The exchange of the fast substrate water in the S 2 state of photosystem II is limited by diffusion of bulk water through channels - implications for the water oxidation mechanism. Chem Sci 2021; 12:12763-12775. [PMID: 34703563 PMCID: PMC8494045 DOI: 10.1039/d1sc02265b] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/31/2021] [Indexed: 12/02/2022] Open
Abstract
The molecular oxygen we breathe is produced from water-derived oxygen species bound to the Mn4CaO5 cluster in photosystem II (PSII). Present research points to the central oxo-bridge O5 as the 'slow exchanging substrate water (Ws)', while, in the S2 state, the terminal water ligands W2 and W3 are both discussed as the 'fast exchanging substrate water (Wf)'. A critical point for the assignment of Wf is whether or not its exchange with bulk water is limited by barriers in the channels leading to the Mn4CaO5 cluster. In this study, we measured the rates of H2 16O/H2 18O substrate water exchange in the S2 and S3 states of PSII core complexes from wild-type (WT) Synechocystis sp. PCC 6803, and from two mutants, D1-D61A and D1-E189Q, that are expected to alter water access via the Cl1/O4 channels and the O1 channel, respectively. We found that the exchange rates of Wf and Ws were unaffected by the E189Q mutation (O1 channel), but strongly perturbed by the D61A mutation (Cl1/O4 channel). It is concluded that all channels have restrictions limiting the isotopic equilibration of the inner water pool near the Mn4CaO5 cluster, and that D61 participates in one such barrier. In the D61A mutant this barrier is lowered so that Wf exchange occurs more rapidly. This finding removes the main argument against Ca-bound W3 as fast substrate water in the S2 state, namely the indifference of the rate of Wf exchange towards Ca/Sr substitution.
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Affiliation(s)
- Casper de Lichtenberg
- Department of Chemistry, Umeå University Linnaeus väg 6 (KBC huset), SE-901 87 Umeå Sweden
- Molecular Biomimetics, Department of Chemistry - Ångström Laboratory, Uppsala University POB 523 SE-75120 Uppsala Sweden
| | - Christopher J Kim
- Department of Biochemistry, University of California Riverside California 92521 USA
| | - Petko Chernev
- Molecular Biomimetics, Department of Chemistry - Ångström Laboratory, Uppsala University POB 523 SE-75120 Uppsala Sweden
| | - Richard J Debus
- Department of Biochemistry, University of California Riverside California 92521 USA
| | - Johannes Messinger
- Department of Chemistry, Umeå University Linnaeus väg 6 (KBC huset), SE-901 87 Umeå Sweden
- Molecular Biomimetics, Department of Chemistry - Ångström Laboratory, Uppsala University POB 523 SE-75120 Uppsala Sweden
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17
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Corry TA, Rummel F, O'Malley PJ. Bonding and Magnetic Exchange Pathways in Nature's Water-Oxidizing Complex. J Phys Chem B 2021; 125:7147-7154. [PMID: 34180671 DOI: 10.1021/acs.jpcb.1c03864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nature of the bonding and magnetic exchange pathways of the water-oxidizing complex of photosystem 2 is explored using broken symmetry density functional theory. The electronic structure and superexchange pathways are illustrated and analyzed using corresponding orbitals and intrinsic bond orbitals. These demonstrate a dominating influence on the bonding and magnetic interactions by both the geometrical structure of the Mn4CaO5 core complex and the ionic interactions of the oxo bridges with the neighboring Ca2+ ion. The demonstrated ionic nature of the Ca2+ bonds is proposed to contribute to the stabilization of the oxygen atoms participating in O-O bond formation.
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Affiliation(s)
- Thomas A Corry
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Felix Rummel
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Patrick J O'Malley
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K
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18
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Zahariou G, Ioannidis N, Sanakis Y, Pantazis DA. Arrested Substrate Binding Resolves Catalytic Intermediates in Higher-Plant Water Oxidation. Angew Chem Int Ed Engl 2021; 60:3156-3162. [PMID: 33030775 PMCID: PMC7898718 DOI: 10.1002/anie.202012304] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/05/2022]
Abstract
Among the intermediate catalytic steps of the water-oxidizing Mn4 CaO5 cluster of photosystem II (PSII), the final metastable S3 state is critically important because it binds one substrate and precedes O2 evolution. Herein, we combine X- and Q-band EPR experiments on native and methanol-treated PSII of Spinacia oleracea and show that methanol-treated PSII preparations of the S3 state correspond to a previously uncharacterized high-spin (S=6) species. This is confirmed as a major component also in intact photosynthetic membranes, coexisting with the previously known intermediate-spin conformation (S=3). The high-spin intermediate is assigned to a water-unbound form, with a MnIV3 subunit interacting ferromagnetically via anisotropic exchange with a coordinatively unsaturated MnIV ion. These results resolve and define the structural heterogeneity of the S3 state, providing constraints on the S3 to S4 transition, on substrate identity and delivery pathways, and on the mechanism of O-O bond formation.
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Affiliation(s)
- Georgia Zahariou
- Institute of Nanoscience & Nanotechnology, NCSR “Demokritos”Athens15310Greece
| | - Nikolaos Ioannidis
- Institute of Nanoscience & Nanotechnology, NCSR “Demokritos”Athens15310Greece
| | - Yiannis Sanakis
- Institute of Nanoscience & Nanotechnology, NCSR “Demokritos”Athens15310Greece
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für KohlenforschungKaiser-Wilhelm-Platz 145470Mülheim an der RuhrGermany
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19
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Orio M, Pantazis DA. Successes, challenges, and opportunities for quantum chemistry in understanding metalloenzymes for solar fuels research. Chem Commun (Camb) 2021; 57:3952-3974. [DOI: 10.1039/d1cc00705j] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Overview of the rich and diverse contributions of quantum chemistry to understanding the structure and function of the biological archetypes for solar fuel research, photosystem II and hydrogenases.
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Affiliation(s)
- Maylis Orio
- Aix-Marseille Université
- CNRS
- iSm2
- Marseille
- France
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung
- Kaiser-Wilhelm-Platz 1
- 45470 Mülheim an der Ruhr
- Germany
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20
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Abstract
We derive a model that provides an exact solution to the substrate-water exchange kinetics in a double-conformation system and use this model to interpret recently published data for Ca2+- and Sr2+-containing PSII in the S2 state, in which the g = 2.0 and g = 4.1 conformations coexist. The component concentrations derived from the kinetic model provide an analytic description of the substrate-water exchange kinetics, allowing us to more accurately interpret the results. Based on this model and the previously reported data on the S2 state g = 2.0 conformation, we obtain the substrate-water exchange rates of the g = 4.1 conformation and the conformational change rates. Two conclusions are made from the analyses. First, contrary to previous reports, there is no significant effect of substituting Sr2+ for Ca2+ on any of the exchange rate constants. Second, the exchange rate of the slowly-exchanging water (Ws) in the S2 state g = 4.1 conformation is much faster than that in the S2 state g = 2.0 conformation. The second conclusion is consistent with the assignment of Ws to W1 or W2 bound as terminal ligands to Mn4; Mn4 has been proposed to undergo an oxidation state change from Mn(IV) in the g = 2.0 conformation to Mn(III) in the g = 4.1 conformation.
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21
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Zahariou G, Ioannidis N, Sanakis Y, Pantazis DA. Arrested Substrate Binding Resolves Catalytic Intermediates in Higher‐Plant Water Oxidation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202012304] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Georgia Zahariou
- Institute of Nanoscience & Nanotechnology, NCSR “Demokritos” Athens 15310 Greece
| | - Nikolaos Ioannidis
- Institute of Nanoscience & Nanotechnology, NCSR “Demokritos” Athens 15310 Greece
| | - Yiannis Sanakis
- Institute of Nanoscience & Nanotechnology, NCSR “Demokritos” Athens 15310 Greece
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1 45470 Mülheim an der Ruhr Germany
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22
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de Lichtenberg C, Avramov AP, Zhang M, Mamedov F, Burnap RL, Messinger J. The D1-V185N mutation alters substrate water exchange by stabilizing alternative structures of the Mn 4Ca-cluster in photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148319. [PMID: 32979346 DOI: 10.1016/j.bbabio.2020.148319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/15/2020] [Accepted: 09/19/2020] [Indexed: 11/30/2022]
Abstract
In photosynthesis, the oxygen-evolving complex (OEC) of the pigment-protein complex photosystem II (PSII) orchestrates the oxidation of water. Introduction of the V185N mutation into the D1 protein was previously reported to drastically slow O2-release and strongly perturb the water network surrounding the Mn4Ca cluster. Employing time-resolved membrane inlet mass spectrometry, we measured here the H218O/H216O-exchange kinetics of the fast (Wf) and slow (Ws) exchanging substrate waters bound in the S1, S2 and S3 states to the Mn4Ca cluster of PSII core complexes isolated from wild type and D1-V185N strains of Synechocystis sp. PCC 6803. We found that the rate of exchange for Ws was increased in the S1 and S2 states, while both Wf and Ws exchange rates were decreased in the S3 state. Additionally, we used EPR spectroscopy to characterize the Mn4Ca cluster and its interaction with the redox active D1-Tyr161 (YZ). In the S2 state, we observed a greatly diminished multiline signal in the V185N-PSII that could be recovered by addition of ammonia. The split signal in the S1 state was not affected, while the split signal in the S3 state was absent in the D1-V185N mutant. These findings are rationalized by the proposal that the N185 residue stabilizes the binding of an additional water-derived ligand at the Mn1 site of the Mn4Ca cluster via hydrogen bonding. Implications for the sites of substrate water binding are discussed.
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Affiliation(s)
- Casper de Lichtenberg
- Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), SE-901 87 Umeå, Sweden; Molecular Biomimetics, Department of Chemistry - Ångström, Uppsala University, POB 523, SE-75120 Uppsala, Sweden
| | - Anton P Avramov
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, United States
| | - Minquan Zhang
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, United States
| | - Fikret Mamedov
- Molecular Biomimetics, Department of Chemistry - Ångström, Uppsala University, POB 523, SE-75120 Uppsala, Sweden
| | - Robert L Burnap
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, United States
| | - Johannes Messinger
- Department of Chemistry, Umeå University, Linnaeus väg 6 (KBC huset), SE-901 87 Umeå, Sweden; Molecular Biomimetics, Department of Chemistry - Ångström, Uppsala University, POB 523, SE-75120 Uppsala, Sweden.
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23
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Kim CJ, Debus RJ. Roles of D1-Glu189 and D1-Glu329 in O2 Formation by the Water-Splitting Mn4Ca Cluster in Photosystem II. Biochemistry 2020; 59:3902-3917. [DOI: 10.1021/acs.biochem.0c00541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher J. Kim
- Department of Biochemistry, University of California, Riverside, California 92521, United States
| | - Richard J. Debus
- Department of Biochemistry, University of California, Riverside, California 92521, United States
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24
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Boussac A, Sellés J, Sugiura M. What can we still learn from the electrochromic band-shifts in Photosystem II? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148176. [PMID: 32061653 DOI: 10.1016/j.bbabio.2020.148176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 01/29/2020] [Accepted: 02/10/2020] [Indexed: 11/17/2022]
Abstract
Electrochromic band-shifts have been investigated in Photosystem II (PSII) from Thermosynechoccocus elongatus. Firstly, by using Mn-depleted PsbA1-PSII and PsbA3-PSII in which the QX absorption of PheD1 differs, a band-shift in the QX region of PheD2 centered at ~ 544 nm has been identified upon the oxidation, at pH 8.6, of TyrD. In contrast, a band-shift due to the formation of either QA•- or TyrZ• is observed in PsbA3-PSII at ~ 546 nm, as expected with E130 H-bonded to PheD1 and at ~ 544 nm as expected with Q130 H-bonded to PheD1. Secondly, electrochromic band-shifts in the Chla Soret region have been measured in O2-evolving PSII in PsbA3-PSII, in the PsbA3/H198Q mutant in which the Soret band of PD1 is blue shifted and in the PsbA3/T179H mutant. Upon TyrZ•QA•- formation the Soret band of PD1 is red shifted and the Soret band of ChlD1 is blue shifted. In contrast, only PD1 undergoes a detectable S-state dependent electrochromism. Thirdly, the time resolved S-state dependent electrochromism attributed to PD1 is biphasic for all the S-state transitions except for S1 to S2, and shows that: i) the proton release in S0 to S1 occurs after the electron transfer and ii) the proton release and the electron transfer kinetics in S2 to S3, in T. elongatus, are significantly faster than often considered. The nature of S2TyrZ• is discussed in view of the models in the literature involving intermediate states in the S2 to S3 transition.
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Affiliation(s)
- Alain Boussac
- I(2)BC, CNRS UMR 9198, CEA Saclay, 91191 Gif-sur-Yvette, France.
| | - Julien Sellés
- Institut de Biologie Physico-Chimique, CNRS UMR 7141 and Sorbonne Université, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Miwa Sugiura
- Proteo-Science Research Center and Graduate School of Science and Technology, Ehime University, Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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25
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Abstract
The oxygen-evolving center (OEC) in photosystem II (PSII) of plants, algae and cyanobacteria is a unique natural catalyst that splits water into electrons, protons and dioxygen. The crystallographic studies of PSII have revealed that the OEC is an asymmetric Mn4CaO5-cluster. The understanding of the structure-function relationship of this natural Mn4CaO5-cluster is impeded mainly due to the complexity of the protein environment and lack of a rational chemical model as a reference. Although it has been a great challenge for chemists to synthesize the OEC in the laboratory, significant advances have been achieved recently. Different artificial complexes have been reported, especially a series of artificial Mn4CaO4-clusters that closely mimic both the geometric and electronic structures of the OEC in PSII, which provides a structurally well-defined chemical model to investigate the structure-function relationship of the natural Mn4CaO5-cluster. The deep investigations on this artificial Mn4CaO4-cluster could provide new insights into the mechanism of the water-splitting reaction in natural photosynthesis and may help the development of efficient catalysts for the water-splitting reaction in artificial photosynthesis.
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26
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de Lichtenberg C, Messinger J. Substrate water exchange in the S2 state of photosystem II is dependent on the conformation of the Mn4Ca cluster. Phys Chem Chem Phys 2020; 22:12894-12908. [DOI: 10.1039/d0cp01380c] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The structural flexibility of the Mn4Ca cluster in photosystem II supports the exchange of the central O5 bridge.
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27
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Ravari AK, Zhu G, Ezhov R, Pineda-Galvan Y, Page A, Weinschenk W, Yan L, Pushkar Y. Unraveling the Mechanism of Catalytic Water Oxidation via de Novo Synthesis of Reactive Intermediate. J Am Chem Soc 2019; 142:884-893. [PMID: 31865704 DOI: 10.1021/jacs.9b10265] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Alireza Karbakhsh Ravari
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Guibo Zhu
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Roman Ezhov
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Yuliana Pineda-Galvan
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Allison Page
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Whitney Weinschenk
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Lifen Yan
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
| | - Yulia Pushkar
- Department of Physics, Purdue University, 525 Northwestern, West Lafayette, Indiana 47907, United States
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