1
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Yocum CF. Photosystem 2 and the oxygen evolving complex: a brief overview. PHOTOSYNTHESIS RESEARCH 2022; 152:97-105. [PMID: 35294671 DOI: 10.1007/s11120-022-00910-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
These special issues of photosynthesis research present papers documenting progress in revealing the many aspects of photosystem 2, a unique, one-of-a-kind complex system that can reduce a plastoquinone to a plastoquinol on every second flash of light and oxidize 2 H2O to an O2 on every fourth flash. This overview is a brief personal assessment of the progress observed by the author over a four-decade research career, including a discussion of some remaining unsolved issues. It will come as no surprise to readers that there are remaining questions given the complexity of PS2, and the efforts that have been needed so far to uncover its secrets. In fact, most readers will have their own lists of outstanding questions.
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Affiliation(s)
- Charles F Yocum
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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2
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Monika, Ansari A. Effect of the ring size of TMC ligands in controlling C-H bond activation by metal-superoxo species. Dalton Trans 2022; 51:5878-5889. [PMID: 35347335 DOI: 10.1039/d2dt00491g] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Metal-superoxo species play a very important role in many metal-mediated catalytic transformation reactions. Their catalytic reactivity is affected by many factors such as the nature of metal ions and ring size of ligands. Herein, for the first time, we report DFT calculations on the electronic structures of a series of metal-superoxo species (M = V, Cr, Mn, Fe, and Co) with two ring size ligands, i.e., 13-TMC/14-TMC, and a detailed mechanistic study on the C-H bond activation of cyclohexa-1,4-diene followed by the effect of the ring size of ligands. Our DFT results showed that the electron density at the distal oxygen plays an important role in C-H bond activation. By computing the energetics of C-H bond activation and mapping the potential energy surface, it was found that the initial hydrogen abstraction is the rate-determining step with both TMC rings and all the studied metal-superoxo species. The significant electron density at the cyclohex-1,4-diene carbon indicates that the reaction proceeds via the proton-coupled electron transfer mechanism. By mapping the potential energy surfaces, we found that the 13-TMC ligated superoxo with the anti-isomer are more reactive than the 14-TMC superoxo species except for the iron-superoxo species where the 14-TMC ligated superoxo species is more reactive i.e. smaller ring size TMC is more reactive towards C-H bond activation. This is also supported by the structural correlation, i.e., the greater contraction in the smaller ring results in the metal being pushed out of plane along the z-axis, which reduces the steric hindrance. Thus, the ring size can help in designing catalysts with better efficiency for catalytic reactions.
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Affiliation(s)
- Monika
- Department of Chemistry, Central University of Haryana, India, 123031.
| | - Azaj Ansari
- Department of Chemistry, Central University of Haryana, India, 123031.
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3
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Bigness A, Vaddypally S, Zdilla MJ, Mendoza-Cortes JL. Ubiquity of cubanes in bioinorganic relevant compounds. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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4
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Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7090131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn4Ca cluster and is known as the oxygen evolving complex (OEC) of PSII. Two tyrosine residues D1-Tyr161 (YZ) and D2-Tyr160 (YD) are symmetrically placed in the two core subunits D1 and D2 and participate in proton coupled electron transfer reactions. YZ of PSII is near the OEC and mediates electron coupled proton transfer from Mn4Ca to the photooxidizable chlorophyll species P680+. YD does not directly interact with OEC, but is crucial for modulating the various S oxidation states of the OEC. In PSII from higher plants the environment of YD• radical has been extensively characterized only in spinach (Spinacia oleracea) Mn-depleted non functional PSII membranes. Here, we present a 2D-HYSCORE investigation in functional PSII of spinach to determine the electronic structure of YD• radical. The hyperfine couplings of the protons that interact with the YD• radical are determined and the relevant assignment is provided. A discussion on the similarities and differences between the present results and the results from studies performed in non functional PSII membranes from higher plants and PSII preparations from other organisms is given.
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5
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Yu J, Zhao C, Zhou R, Gao W, Wang S, Liu K, Chen S, Hu K, Mei L, Yuan L, Chai Z, Hu H, Shi W. Visible-Light-Enabled C-H Functionalization by a Direct Hydrogen Atom Transfer Uranyl Photocatalyst. Chemistry 2020; 26:16521-16529. [PMID: 32901978 DOI: 10.1002/chem.202003431] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/01/2020] [Indexed: 11/11/2022]
Abstract
The development of the uranyl cation as a powerful photocatalyst is seriously delayed in comparison with the advances in its fundamental and structural chemistry. However, its characteristic high oxidative capability in the excited state ([UO2 ]2+ * (+2.6 V vs. SHE; SHE=standard hydrogen electrode) combined with blue-light absorption (hv=380-500 nm) and a long-lived fluorescence lifetime up to microseconds have reveals that the uranyl cation approaches an ideal photocatalyst for visible-light-driven organic transformations. Described herein is the successful use of uranyl nitrate as a photocatalyst to enable C(sp3 )-H activation and C-C bond formation through hydrogen atom transfer (HAT) under blue-light irradiation. In particular, this operationally simple strategy provides an appropriate approach to the synthesis of diverse and valuable diarylmethane motifs. Mechanistic studies and DFT calculations have provided insights into the detailed mechanism of the photoinduced HAT pathway. This research suggests a general platform that could popularize promising uranyl photocatalytic performance.
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Affiliation(s)
- Jipan Yu
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Chongyang Zhao
- Department of Chemistry, Key Laboratory of Organic Optoelectronics and, Molecular Engineering of Ministry of Education, Tsinghua University, Beijing, 100084, P.R. China
| | - Rong Zhou
- College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, P.R. China
| | - Wenchao Gao
- College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, P.R. China
| | - Shuai Wang
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Kang Liu
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Siyu Chen
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Kongqiu Hu
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Lei Mei
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Liyong Yuan
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Zhifang Chai
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China.,Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo, 315201, P.R. China
| | - Hanshi Hu
- Department of Chemistry, Key Laboratory of Organic Optoelectronics and, Molecular Engineering of Ministry of Education, Tsinghua University, Beijing, 100084, P.R. China
| | - Weiqun Shi
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
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6
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Ibrahim M, Fransson T, Chatterjee R, Cheah MH, Hussein R, Lassalle L, Sutherlin KD, Young ID, Fuller FD, Gul S, Kim IS, Simon PS, de Lichtenberg C, Chernev P, Bogacz I, Pham CC, Orville AM, Saichek N, Northen T, Batyuk A, Carbajo S, Alonso-Mori R, Tono K, Owada S, Bhowmick A, Bolotovsky R, Mendez D, Moriarty NW, Holton JM, Dobbek H, Brewster AS, Adams PD, Sauter NK, Bergmann U, Zouni A, Messinger J, Kern J, Yachandra VK, Yano J. Untangling the sequence of events during the S 2 → S 3 transition in photosystem II and implications for the water oxidation mechanism. Proc Natl Acad Sci U S A 2020; 117:12624-12635. [PMID: 32434915 PMCID: PMC7293653 DOI: 10.1073/pnas.2000529117] [Citation(s) in RCA: 141] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In oxygenic photosynthesis, light-driven oxidation of water to molecular oxygen is carried out by the oxygen-evolving complex (OEC) in photosystem II (PS II). Recently, we reported the room-temperature structures of PS II in the four (semi)stable S-states, S1, S2, S3, and S0, showing that a water molecule is inserted during the S2 → S3 transition, as a new bridging O(H)-ligand between Mn1 and Ca. To understand the sequence of events leading to the formation of this last stable intermediate state before O2 formation, we recorded diffraction and Mn X-ray emission spectroscopy (XES) data at several time points during the S2 → S3 transition. At the electron acceptor site, changes due to the two-electron redox chemistry at the quinones, QA and QB, are observed. At the donor site, tyrosine YZ and His190 H-bonded to it move by 50 µs after the second flash, and Glu189 moves away from Ca. This is followed by Mn1 and Mn4 moving apart, and the insertion of OX(H) at the open coordination site of Mn1. This water, possibly a ligand of Ca, could be supplied via a "water wheel"-like arrangement of five waters next to the OEC that is connected by a large channel to the bulk solvent. XES spectra show that Mn oxidation (τ of ∼350 µs) during the S2 → S3 transition mirrors the appearance of OX electron density. This indicates that the oxidation state change and the insertion of water as a bridging atom between Mn1 and Ca are highly correlated.
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Affiliation(s)
- Mohamed Ibrahim
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10115 Berlin, Germany
| | - Thomas Fransson
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, 69120 Heidelberg, Germany
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Mun Hon Cheah
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden
| | - Rana Hussein
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10115 Berlin, Germany
| | - Louise Lassalle
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Kyle D Sutherlin
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Iris D Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Franklin D Fuller
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - In-Sik Kim
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Philipp S Simon
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Casper de Lichtenberg
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden
- Institutionen för Kemi, Kemiskt Biologiskt Centrum, Umeå Universitet, SE 90187 Umeå, Sweden
| | - Petko Chernev
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden
| | - Isabel Bogacz
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Cindy C Pham
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Allen M Orville
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, OX11 0DE Didcot, United Kingdom
- Research Complex at Harwell, Rutherford Appleton Laboratory, OX11 0FA Didcot, United Kingdom
| | - Nicholas Saichek
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Trent Northen
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Alexander Batyuk
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Sergio Carbajo
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, Sayo-cho, Sayo-gun, 679-5198 Hyogo, Japan
- RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, 679-5148 Hyogo, Japan
| | - Shigeki Owada
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Japan Synchrotron Radiation Research Institute, Sayo-cho, Sayo-gun, 679-5198 Hyogo, Japan
| | - Asmit Bhowmick
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Robert Bolotovsky
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Derek Mendez
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Nigel W Moriarty
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - James M Holton
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
| | - Holger Dobbek
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10115 Berlin, Germany
| | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Paul D Adams
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Department of Bioengineering, University of California, Berkeley, CA 94720
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Uwe Bergmann
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025
| | - Athina Zouni
- Institut für Biologie, Humboldt-Universität zu Berlin, D-10115 Berlin, Germany;
| | - Johannes Messinger
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75120 Uppsala, Sweden;
- Institutionen för Kemi, Kemiskt Biologiskt Centrum, Umeå Universitet, SE 90187 Umeå, Sweden
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Vittal K Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
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7
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Sen A, Vyas N, Pandey B, Jaccob M, Rajaraman G. Mechanistic Insights on the Formation of High‐Valent Mn
III/IV
=O Species Using Oxygen as Oxidant: A Theoretical Perspective. Isr J Chem 2020. [DOI: 10.1002/ijch.201900142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Asmita Sen
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
| | - Nidhi Vyas
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
- School of Biotechnology Jawaharlal Nehru University New Delhi 110067 India
| | - Bhawana Pandey
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
| | - Madhavan Jaccob
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
- Department of chemistry Loyola College Chennai 600 034
| | - Gopalan Rajaraman
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
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8
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Yee EF, Dzikovski B, Crane BR. Tuning Radical Relay Residues by Proton Management Rescues Protein Electron Hopping. J Am Chem Soc 2019; 141:17571-17587. [PMID: 31603693 DOI: 10.1021/jacs.9b05715] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Transient tyrosine and tryptophan radicals play key roles in the electron transfer (ET) reactions of photosystem (PS) II, ribonucleotide reductase (RNR), photolyase, and many other proteins. However, Tyr and Trp are not functionally interchangeable, and the factors controlling their reactivity are often unclear. Cytochrome c peroxidase (CcP) employs a Trp191•+ radical to oxidize reduced cytochrome c (Cc). Although a Tyr191 replacement also forms a stable radical, it does not support rapid ET from Cc. Here we probe the redox properties of CcP Y191 by non-natural amino acid substitution, altering the ET driving force and manipulating the protic environment of Y191. Higher potential fluorotyrosine residues increase ET rates marginally, but only addition of a hydrogen bond donor to Tyr191• (via Leu232His or Glu) substantially alters activity by increasing the ET rate by nearly 30-fold. ESR and ESEEM spectroscopies, crystallography, and pH-dependent ET kinetics provide strong evidence for hydrogen bond formation to Y191• by His232/Glu232. Rate measurements and rapid freeze quench ESR spectroscopy further reveal differences in radical propagation and Cc oxidation that support an increased Y191• formal potential of ∼200 mV in the presence of E232. Hence, Y191 inactivity results from a potential drop owing to Y191•+ deprotonation. Incorporation of a well-positioned base to accept and donate back a hydrogen bond upshifts the Tyr• potential into a range where it can effectively oxidize Cc. These findings have implications for the YZ/YD radicals of PS II, hole-hopping in RNR and cryptochrome, and engineering proteins for long-range ET reactions.
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Affiliation(s)
- Estella F Yee
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Boris Dzikovski
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States.,National Biomedical Center for Advanced ESR Technologies (ACERT) , Cornell University , Ithaca , New York 14850 , United States
| | - Brian R Crane
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
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9
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Kawashima K, Saito K, Ishikita H. Mechanism of Radical Formation in the H-Bond Network of D1-Asn298 in Photosystem II. Biochemistry 2018; 57:4997-5004. [DOI: 10.1021/acs.biochem.8b00574] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Keisuke Kawashima
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Keisuke Saito
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Hiroshi Ishikita
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
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10
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Cho J, Kwak J, Oh J, Kim D, Lee SY. Photoinduced Intermolecular Electron Transfer Mediated by the Colloidal Tyrosyl Bolaamphiphile Assembly. Chemphyschem 2018; 19:643-650. [DOI: 10.1002/cphc.201701099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Junghyun Cho
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 03722 Republic of Korea), Fax: (+82) 2-312-6401
| | - Jinyoung Kwak
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 03722 Republic of Korea), Fax: (+82) 2-312-6401
| | - Juwon Oh
- Spectroscopy Laboratory for Functional π-Electron Systems; and Department of Chemistry; Yonsei University; Seoul 03722 Republic of Korea
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-Electron Systems; and Department of Chemistry; Yonsei University; Seoul 03722 Republic of Korea
| | - Sang-Yup Lee
- Department of Chemical and Biomolecular Engineering; Yonsei University; Seoul 03722 Republic of Korea), Fax: (+82) 2-312-6401
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11
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Rice DB, Wijeratne GB, Burr AD, Parham JD, Day VW, Jackson TA. Steric and Electronic Influence on Proton-Coupled Electron-Transfer Reactivity of a Mononuclear Mn(III)-Hydroxo Complex. Inorg Chem 2016; 55:8110-20. [PMID: 27490691 DOI: 10.1021/acs.inorgchem.6b01217] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mononuclear hydroxomanganese(III) complex was synthesized utilizing the N5 amide-containing ligand 2-[bis(pyridin-2-ylmethyl)]amino-N-2-methyl-quinolin-8-yl-acetamidate (dpaq(2Me) ). This complex is similar to previously reported [Mn(III)(OH)(dpaq(H))](+) [Inorg. Chem. 2014, 53, 7622-7634] but contains a methyl group adjacent to the hydroxo moiety. This α-methylquinoline group in [Mn(III)(OH)(dpaq(2Me))](+) gives rise to a 0.1 Å elongation in the Mn-N(quinoline) distance relative to [Mn(III)(OH)(dpaq(H))](+). Similar bond elongation is observed in the corresponding Mn(II) complex. In MeCN, [Mn(III)(OH)(dpaq(2Me))](+) reacts rapidly with 2,2',6,6'-tetramethylpiperidine-1-ol (TEMPOH) at -35 °C by a concerted proton-electron transfer (CPET) mechanism (second-order rate constant k2 of 3.9(3) M(-1) s(-1)). Using enthalpies and entropies of activation from variable-temperature studies of TEMPOH oxidation by [Mn(III)(OH)(dpaq(2Me))](+) (ΔH(‡) = 5.7(3) kcal(-1) M(-1); ΔS(‡) = -41(1) cal M(-1) K(-1)), it was determined that [Mn(III)(OH)(dpaq(2Me))](+) oxidizes TEMPOH ∼240 times faster than [Mn(III)(OH)(dpaq(H))](+). The [Mn(III)(OH)(dpaq(2Me))](+) complex is also capable of oxidizing the stronger O-H and C-H bonds of 2,4,6-tri-tert-butylphenol and xanthene, respectively. However, for these reactions [Mn(III)(OH)(dpaq(2Me))](+) displays, at best, modest rate enhancement relative to [Mn(III)(OH)(dpaq(H))](+). A combination of density function theory (DFT) and cyclic voltammetry studies establish an increase in the Mn(III)/Mn(II) reduction potential of [Mn(III)(OH)(dpaq(2Me))](+) relative to [Mn(III)(OH)(dpaq(H))](+), which gives rise to a larger driving force for CPET for the former complex. Thus, more favorable thermodynamics for [Mn(III)(OH)(dpaq(2Me))](+) can account for the dramatic increase in rate with TEMPOH. For the more sterically encumbered substrates, DFT computations suggest that this effect is mitigated by unfavorable steric interactions between the substrate and the α-methylquinoline group of the dpaq(2Me) ligand. The DFT calculations, which reproduce the experimental activation free energies quite well, provide the first examination of the transition-state structure of mononuclear Mn(III)(OH) species during a CPET reaction.
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Affiliation(s)
- Derek B Rice
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
| | - Gayan B Wijeratne
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
| | - Andrew D Burr
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
| | - Joshua D Parham
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
| | - Victor W Day
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
| | - Timothy A Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
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12
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Hayashi T, Yamaguchi A, Hashimoto K, Nakamura R. Stability of organic compounds on the oxygen-evolving center of photosystem II and manganese oxide water oxidation catalysts. Chem Commun (Camb) 2016; 52:13760-13763. [DOI: 10.1039/c6cc07092b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Carboxyl groups, abundant residues around the Mn4cluster of photosystem II, stably facilitated electrochemical water oxidation by Mn oxides.
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Affiliation(s)
- Toru Hayashi
- Department of Applied Chemistry
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Akira Yamaguchi
- Biofunctional Catalyst Research Team
- RIKEN Center for Sustainable Resource Science (CSRS)
- Wako
- Japan
| | | | - Ryuhei Nakamura
- Biofunctional Catalyst Research Team
- RIKEN Center for Sustainable Resource Science (CSRS)
- Wako
- Japan
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13
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Oliver TAA, Zhang Y, Roy A, Ashfold MNR, Bradforth SE. Exploring Autoionization and Photoinduced Proton-Coupled Electron Transfer Pathways of Phenol in Aqueous Solution. J Phys Chem Lett 2015; 6:4159-4164. [PMID: 26722792 DOI: 10.1021/acs.jpclett.5b01861] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The excited state dynamics of phenol in water have been investigated using transient absorption spectroscopy. Solvated electrons and vibrationally cold phenoxyl radicals are observed upon 200 and 267 nm excitation, but with formation time scales that differ by more than 4 orders of magnitude. The impact of these findings is assessed in terms of the relative importance of autoionization versus proton-coupled electron transfer mechanisms in this computationally tractable model system.
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Affiliation(s)
- Thomas A A Oliver
- School of Chemistry, University of Bristol , Bristol, BS8 1TS, United Kingdom
| | - Yuyuan Zhang
- University of Southern California , Los Angeles, California 90089, United States
| | - Anirban Roy
- University of Southern California , Los Angeles, California 90089, United States
| | - Michael N R Ashfold
- School of Chemistry, University of Bristol , Bristol, BS8 1TS, United Kingdom
| | - Stephen E Bradforth
- University of Southern California , Los Angeles, California 90089, United States
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14
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Zhang Z, Coats KL, Chen Z, Hubin TJ, Yin G. Influence of Calcium(II) and Chloride on the Oxidative Reactivity of a Manganese(II) Complex of a Cross-Bridged Cyclen Ligand. Inorg Chem 2014; 53:11937-47. [DOI: 10.1021/ic501342c] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Zhan Zhang
- Key
Laboratory for Large-Format Battery Materials and System, Ministry
of Education, School of Chemistry and Chemical Engineering, Hubei
Key Laboratory of Material Chemistry and Service Failure, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Katherine L. Coats
- Department
of Chemistry and Physics, Southwestern Oklahoma State University, 100
Campus Drive, Weatherford, Oklahoma 73096, United States
| | - Zhuqi Chen
- Key
Laboratory for Large-Format Battery Materials and System, Ministry
of Education, School of Chemistry and Chemical Engineering, Hubei
Key Laboratory of Material Chemistry and Service Failure, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
| | - Timothy J. Hubin
- Department
of Chemistry and Physics, Southwestern Oklahoma State University, 100
Campus Drive, Weatherford, Oklahoma 73096, United States
| | - Guochuan Yin
- Key
Laboratory for Large-Format Battery Materials and System, Ministry
of Education, School of Chemistry and Chemical Engineering, Hubei
Key Laboratory of Material Chemistry and Service Failure, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
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15
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Wijeratne GB, Corzine B, Day VW, Jackson TA. Saturation kinetics in phenolic O-H bond oxidation by a mononuclear Mn(III)-OH complex derived from dioxygen. Inorg Chem 2014; 53:7622-34. [PMID: 25010596 DOI: 10.1021/ic500943k] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The mononuclear hydroxomanganese(III) complex, [Mn(III)(OH)(dpaq)](+), which is supported by the amide-containing N5 ligand dpaq (dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate) was generated by treatment of the manganese(II) species, [Mn(II)(dpaq)](OTf), with dioxygen in acetonitrile solution at 25 °C. This oxygenation reaction proceeds with essentially quantitative yield (greater than 98% isolated yield) and represents a rare example of an O2-mediated oxidation of a manganese(II) complex to generate a single product. The X-ray diffraction structure of [Mn(III)(OH)(dpaq)](+) reveals a short Mn-OH distance of 1.806(13) Å, with the hydroxo moiety trans to the amide function of the dpaq ligand. No shielding of the hydroxo group is observed in the solid-state structure. Nonetheless, [Mn(III)(OH)(dpaq)](+) is remarkably stable, decreasing in concentration by only 10% when stored in MeCN at 25 °C for 1 week. The [Mn(III)(OH)(dpaq)](+) complex participates in proton-coupled electron transfer reactions with substrates with relatively weak O-H and C-H bonds. For example, [Mn(III)(OH)(dpaq)](+) oxidizes TEMPOH (TEMPOH = 2,2'-6,6'-tetramethylpiperidine-1-ol), which has a bond dissociation free energy (BDFE) of 66.5 kcal/mol, in MeCN at 25 °C. The hydrogen/deuterium kinetic isotope effect of 1.8 observed for this reaction implies a concerted proton-electron transfer pathway. The [Mn(III)(OH)(dpaq)](+) complex also oxidizes xanthene (C-H BDFE of 73.3 kcal/mol in dimethylsulfoxide) and phenols, such as 2,4,6-tri-t-butylphenol, with BDFEs of less than 79 kcal/mol. Saturation kinetics were observed for phenol oxidation, implying an initial equilibrium prior to the rate-determining step. On the basis of a collective body of evidence, the equilibrium step is attributed to the formation of a hydrogen-bonding complex between [Mn(III)(OH)(dpaq)](+) and the phenol substrates.
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Affiliation(s)
- Gayan B Wijeratne
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States
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16
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Ashe D, Alleyne T, Wilson M, Svistunenko D, Nicholls P. Redox equilibration after one-electron reduction of cytochrome c oxidase: radical formation and a possible hydrogen relay mechanism. Arch Biochem Biophys 2014; 554:36-43. [PMID: 24811894 DOI: 10.1016/j.abb.2014.04.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/09/2014] [Accepted: 04/25/2014] [Indexed: 11/17/2022]
Abstract
Kinetic studies using UV/visible and EPR spectroscopy were carried out to follow the distribution of electrons within beef heart cytochrome c oxidase (CcO), both active and cyanide-inhibited, following addition of reduced cytochrome c as electron donor. In the initial one-electron reduced state the electron is shared between three redox centers, heme a, CuA and a third site, probably CuB. Using a rapid freeze system and the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) a protein radical was also detected. The EPR spectrum of the DMPO adduct of this radical was consistent with tyrosyl radical capture. This may be a feature of a charge relay mechanism involved in some part of the CcO electron transfer system from bound cytochrome c via CuA and heme a to the a3CuB binuclear center.
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Affiliation(s)
- Damian Ashe
- Biochemistry Unit, Department of Pre-Clinical Sciences, Faculty of Medical Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Trevor Alleyne
- Biochemistry Unit, Department of Pre-Clinical Sciences, Faculty of Medical Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Michael Wilson
- Molecular Biophysics Research Group, School of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UK
| | - Dimitri Svistunenko
- Molecular Biophysics Research Group, School of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UK
| | - Peter Nicholls
- Molecular Biophysics Research Group, School of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UK.
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17
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Kuchenreuther JM, Myers WK, Stich TA, George SJ, NejatyJahromy Y, Swartz JR, Britt RD. A Radical Intermediate in Tyrosine Scission to the CO and CN- Ligands of FeFe Hydrogenase. Science 2013; 342:472-5. [DOI: 10.1126/science.1241859] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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18
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Bonin J, Robert M. Photoinduced Proton-Coupled Electron Transfers in Biorelevant Phenolic Systems. Photochem Photobiol 2011; 87:1190-203. [DOI: 10.1111/j.1751-1097.2011.00996.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Service RJ, Yano J, McConnell I, Hwang HJ, Niks D, Hille R, Wydrzynski T, Burnap RL, Hillier W, Debus RJ. Participation of glutamate-354 of the CP43 polypeptide in the ligation of manganese and the binding of substrate water in photosystem II. Biochemistry 2010; 50:63-81. [PMID: 21114287 DOI: 10.1021/bi1015937] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the current X-ray crystallographic structural models of photosystem II, Glu354 of the CP43 polypeptide is the only amino acid ligand of the oxygen-evolving Mn(4)Ca cluster that is not provided by the D1 polypeptide. To further explore the influence of this structurally unique residue on the properties of the Mn(4)Ca cluster, the CP43-E354Q mutant of the cyanobacterium Synechocystis sp. PCC 6803 was characterized with a variety of biophysical and spectroscopic methods, including polarography, EPR, X-ray absorption, FTIR, and mass spectrometry. The kinetics of oxygen release in the mutant were essentially unchanged from those in wild type. In addition, the oxygen flash yields exhibited normal period four oscillations having normal S state parameters, although the yields were lower, correlating with the mutant's lower steady-state rate (approximately 20% compared to wild type). Experiments conducted with H(2)(18)O showed that the fast and slow phases of substrate water exchange in CP43-E354Q thylakoid membranes were accelerated 8.5- and 1.8-fold, respectively, in the S(3) state compared to wild type. Purified oxygen-evolving CP43-E354Q PSII core complexes exhibited a slightly altered S(1) state Mn-EXAFS spectrum, a slightly altered S(2) state multiline EPR signal, a substantially altered S(2)-minus-S(1) FTIR difference spectrum, and an unusually long lifetime for the S(2) state (>10 h) in a substantial fraction of reaction centers. In contrast, the S(2) state Mn-EXAFS spectrum was nearly indistinguishable from that of wild type. The S(2)-minus-S(1) FTIR difference spectrum showed alterations throughout the amide and carboxylate stretching regions. Global labeling with (15)N and specific labeling with l-[1-(13)C]alanine revealed that the mutation perturbs both amide II and carboxylate stretching modes and shifts the symmetric carboxylate stretching modes of the α-COO(-) group of D1-Ala344 (the C-terminus of the D1 polypeptide) to higher frequencies by 3-4 cm(-1) in both the S(1) and S(2) states. The EPR and FTIR data implied that 76-82% of CP43-E354Q PSII centers can achieve the S(2) state and that most of these can achieve the S(3) state, but no evidence for advancement beyond the S(3) state was observed in the FTIR data, at least not in a majority of PSII centers. Although the X-ray absorption and EPR data showed that the CP43-E354Q mutation only subtly perturbs the structure and spin state of the Mn(4)Ca cluster in the S(2) state, the FTIR and H(2)(18)O exchange data show that the mutation strongly influences other properties of the Mn(4)Ca cluster, altering the response of numerous carboxylate and amide groups to the increased positive charge that develops on the cluster during the S(1) to S(2) transition and weakening the binding of both substrate water molecules (or water-derived ligands), especially the one that exchanges rapidly in the S(3) state. The FTIR data provide evidence that CP43-Glu354 coordinates to the Mn(4)Ca cluster in the S(1) state as a bridging ligand between two metal ions but provide no compelling evidence that this residue changes its coordination mode during the S(1) to S(2) transition. The H(2)(18)O exchange data provide evidence that CP43-Glu354 interacts with the Mn ion that ligates the substrate water molecule (or water-derived ligand) that is in rapid exchange in the S(3) state.
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Affiliation(s)
- Rachel J Service
- Department of Biochemistry, University of California, Riverside, California 92521, United States
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20
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Haddy A, Ore BM. An alternative method for calcium depletion of the oxygen evolving complex of photosystem II as revealed by the dark-stable multiline EPR signal. Biochemistry 2010; 49:3805-14. [PMID: 20373758 DOI: 10.1021/bi901700n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dark-stable multiline EPR signal of photosystem II (PSII) is associated with a slow-decaying S(2) state that is due to Ca(2+) loss from the oxygen evolving complex. Formation of the signal was observed in intact PSII in the presence of 100-250 mM NaCl at pH 5.5. Both moderately high NaCl concentration and decreased pH were required for its appearance in intact PSII. It was estimated that only a portion of oxygen evolving complexes was responsible for the signal (about 20% in 250 mM NaCl), based on the loss of the normal S(2)-state multiline signal. The formation of the dark-stable multiline signal in intact PSII at pH 5.5 could be reversed by addition of 15 mM Ca(2+) in the presence of moderately high NaCl, confirming that it was the absence of Ca(2+) that led to its appearance. Formation of the dark-stable multiline signal in NaCl-washed PSII, which lacks the PsbP (23 kDa) and PsbQ (17 kDa) subunits, was observed in about 80% of the sample in the presence of 150 mM NaCl at pH 5.5, but some signal was also observed under normal buffer conditions. In both intact and NaCl-washed PSII, the S(2)Y(Z). signal, which is also characteristic of Ca(2+) depletion, appeared upon subsequent illumination. Formation of the dark-stable multiline signal took place in the absence of Ca(2+) chelator or polycarboxylic acids, indicating that the signal did not require their direct binding as has been proposed previously. The conditions used here were milder than those used to produce the signal in previous studies and included a preillumination protocol to maximize the dark-stable S(2) state. Based on these conditions, it is suggested that Ca(2+) release occurred through protonation of key residues that coordinate Ca(2+) at low pH, followed by displacement of Ca(2+) with Na(+) by mass action at the moderately high NaCl concentration.
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Affiliation(s)
- Alice Haddy
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, North Carolina 27402, USA.
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21
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22
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Bögershausen O, Haumann M, Junge W. Photosynthetic oxygen evolution: H/D isotope effects and the coupling between electron and proton transfer during transitions S2⟹3 and S3⟹S4→S0. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19961001210] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Lee YK, Whittaker MM, Whittaker JW. The electronic structure of the Cys-Tyr(*) free radical in galactose oxidase determined by EPR spectroscopy. Biochemistry 2010; 47:6637-49. [PMID: 18512952 DOI: 10.1021/bi800305d] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Galactose oxidase is a metalloenzyme containing a novel metalloradical complex in its active site, comprised of a mononuclear copper ion associated with a protein free radical. The free radical has been shown to be localized on an intrinsic redox cofactor, 3'-(S-cysteinyl)tyrosine (Cys-Tyr), formed by a posttranslational covalent coupling of tyrosine and cysteine side chains in a self-processing reaction. The role of the thioether linkage in the function of the Cys-Tyr cofactor is unresolved, and some computational studies have suggested that the thioether substituent has a negligible effect on the properties of the tyrosyl free radical. In order to address this question experimentally, we have incorporated site-selectively labeled tyrosine ((2)H, (13)C, (17)O) into galactose oxidase using an engineered tyrosine auxotroph strain of Pichia pastoris . (33)S was also incorporated into the protein. EPR spectra for the Cys-Tyr(*) free radical in each of these isotopic variants were analyzed to extract nuclear hyperfine parameters for comparison with theoretical predictions, and the unpaired spin distribution in the free radical was reconstructed from the hyperfine data. These labeling studies allow the first comprehensive experimental evaluation of the effect of the thioether linkage on the properties of Cys-Tyr(*) and indicate that previous calculations significantly underestimated the contribution of this feature to the electronic ground state of the free radical.
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Affiliation(s)
- Yuk-Ki Lee
- Department of Environmental and Biomolecular Systems, OGI School of Science and Engineering, Oregon Health and Science University, 20000 Northwest Walker Road, Beaverton, Oregon 97006-8921, USA
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24
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Ren Y, Zhang C, Bao H, Shen J, Zhao J. Probing tyrosine Z oxidation in Photosystem II core complex isolated from spinach by EPR at liquid helium temperatures. PHOTOSYNTHESIS RESEARCH 2009; 99:127-138. [PMID: 19214772 DOI: 10.1007/s11120-009-9410-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 01/23/2009] [Indexed: 05/27/2023]
Abstract
Tyrosine Z (Tyr(Z)) oxidation observed at liquid helium temperatures provides new insights into the structure and function of Tyr(Z) in active Photosystem II (PSII). However, it has not been reported in PSII core complex from higher plants. Here, we report Tyr(Z) oxidation in the S(1) and S(2) states in PSII core complex from spinach for the first time. Moreover, we identified a 500 G-wide symmetric EPR signal (peak position g = 2.18, trough position g = 1.85) together with the g = 2.03 signal induced by visible light at 10 K in the S(1) state in the PSII core complex. These two signals decay with a similar rate in the dark and both disappear in the presence of 6% methanol. We tentatively assign this new feature to the hyperfine structure of the S(1)Tyr(Z)(*) EPR signal. Furthermore, EPR signals of the S(2) state of the Mn-cluster, the oxidation of the non-heme iron, and the S(1)Tyr(Z)(*) in PSII core complexes and PSII-enriched membranes from spinach are compared, which clearly indicate that both the donor and acceptor sides of the reaction center are undisturbed after the removal of LHCII. These results suggest that the new spinach PSII core complex is suitable for the electron transfer study of PSII at cryogenic temperatures.
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Affiliation(s)
- Yanan Ren
- Laboratory of Photochemistry, Beijing National Laboratory of Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
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25
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Teutloff C, Pudollek S, Keßen S, Broser M, Zouni A, Bittl R. Electronic structure of the tyrosine D radical and the water-splitting complex from pulsed ENDOR spectroscopy on photosystem II single crystals. Phys Chem Chem Phys 2009; 11:6715-26. [DOI: 10.1039/b908093g] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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26
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Mino H, Kawamori A. The differences in microenvironments and functions of tyrosine radicals YZ and YD in photosystem II studied by EPR. PHOTOSYNTHESIS RESEARCH 2008; 98:151-157. [PMID: 18985433 DOI: 10.1007/s11120-008-9380-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Accepted: 10/09/2008] [Indexed: 05/27/2023]
Abstract
Electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) were performed to investigate the difference in microenvironments and functions between tyrosine Z (Y(Z)) and tyrosine D (Y(D)). Mn-depletion or Ca(2+)-depletion causes extension of the lifetime of tyrosine radical Y(Z)(*), which can be trapped by rapid freezing after illumination at about 250 K. Above pH 6.5, Y(Z)(*) radical in Mn-depleted PS II shows similar EPR and ENDOR spectra similar to that of Y(D)(*) radical, which are ascribed to a typical neutral tyrosine radical. Below pH 6.5, Y(Z)(*) radical shows quite different EPR and ENDOR spectra. ENDOR spectra show the spin density distribution of the low-pH form of Y(Z)(*) that has been quite different from the high-pH form of Y(Z)(*). The spin density distribution of the low-pH Y(Z)(*) can be explained by a cation radical or the neutral radical induced by strong electrostatic interaction. The pH dependence of the activation energy of the recombination rate between Y(Z)(*) and Q(A)(-) shows a gap of 4.4 kJ/mol at pH 6.0-6.5. In the Ca(2+)-depleted PS II, Y(Z)(*) signal was the mixture of the cation-like and normal neutral radicals, and the pH dependence of Y(Z)(*) spectrum in Ca(2+)-depleted PS II is considerably different from the neutral radical found in Mn-depleted PS II. Based on the recent structure data of cyanobacterial PS II, the pH dependence of Y(Z)(*) could be ascribed to the modification of the local structure and hydrogen-bonding network induced by the dissociation of ASP170 near Y(Z).
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Affiliation(s)
- Hiroyuki Mino
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan.
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27
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Bao H, Zhang C, Kawakami K, Ren Y, Shen JR, Zhao J. Acceptor side effects on the electron transfer at cryogenic temperatures in intact photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1109-15. [DOI: 10.1016/j.bbabio.2008.04.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 04/16/2008] [Accepted: 04/16/2008] [Indexed: 10/22/2022]
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28
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Clausen J, Junge W. The terminal reaction cascade of water oxidation: proton and oxygen release. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1311-8. [PMID: 18640091 DOI: 10.1016/j.bbabio.2008.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 06/09/2008] [Accepted: 06/12/2008] [Indexed: 10/21/2022]
Abstract
In cyanobacteria, algae and plants Photosystem II produces the oxygen we breathe. Driven and clocked by light quanta, the catalytic Mn(4)Ca-tyrosine centre accumulates four oxidising equivalents before it abstracts four electrons from water, liberating dioxygen and protons. Aiming at intermediates of the terminal four-electron cascade, we previously have suppressed this reaction by elevating the oxygen pressure, thereby stabilising one redox intermediate. Here, we established a similar suppression by increasing the proton concentration. Data were analysed in terms of only one (peroxy) redox intermediate between the fourfold oxidised Mn(4)Ca-tyrosine centre and oxygen release. The surprising result was that the release into the bulk of one proton per dioxygen is linked to the first and rate-limiting electron transfer in the cascade rather than to the second which produces free oxygen. The penultimate intermediate might thus be conceived as a fully deprotonated peroxy-moiety.
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Affiliation(s)
- Juergen Clausen
- Abteilung Biophysik, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
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29
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Moore GF, Hambourger M, Gervaldo M, Poluektov OG, Rajh T, Gust D, Moore TA, Moore AL. A bioinspired construct that mimics the proton coupled electron transfer between P680*+ and the Tyr(Z)-His190 pair of photosystem II. J Am Chem Soc 2008; 130:10466-7. [PMID: 18642819 DOI: 10.1021/ja803015m] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A bioinspired hybrid system, composed of colloidal TiO2 nanoparticles surface modified with a photochemically active mimic of the PSII chlorophyll-Tyr-His complex, undergoes photoinduced stepwise electron transfer coupled to proton motion at the phenolic site. Low temperature electron paramagnetic resonance studies reveal that injected electrons are localized on TiO2 nanoparticles following photoexcitation. At 80 K, 95% of the resulting holes are localized on the phenol moiety and 5% are localized on the porphyrin. At 4.2 K, 52% of the holes remain trapped on the porphyrin. The anisotropic coupling tensors of the phenoxyl radical are resolved in the photoinduced D-band EPR spectra and are in good agreement with previously reported g-tensors of tyrosine radicals in photosystem II. The observed temperature dependence of the charge shift is attributed to restricted nuclear motion at low temperature and is reminiscent of the observation of a trapped high-energy state in the natural system. Electrochemical studies show that the phenoxyl/phenol couple of the model system is chemically reversible and thermodynamically capable of water oxidation.
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Affiliation(s)
- Gary F Moore
- Center for Bioenergy and Photosynthesis, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA
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30
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Ioannidis N, Zahariou G, Petrouleas V. The EPR spectrum of tyrosine Z* and its decay kinetics in O2-evolving photosystem II preparations. Biochemistry 2008; 47:6292-300. [PMID: 18494501 DOI: 10.1021/bi800390r] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The O2-evolving complex of photosystem II, Mn 4Ca, cycles through five oxidation states, S0,..., S4, during its catalytic function, which involves the gradual abstraction of four electrons and four protons from two bound water molecules. The direct oxidant of the complex is the tyrosine neutral radical, YZ(*), which is transiently produced by the highly oxidizing power of the photoexcited chlorophyll species P680. EPR characterization of YZ(*) has been limited, until recently, to inhibited (non-oxygen-evolving) preparations. A number of relatively recent papers have demonstrated the trapping of YZ(*) in O2-evolving preparations at liquid helium temperatures as an intermediate of the S0 to S1, S1 to S2, and S2 to S3 transitions. The respective EPR spectra are broadened and split at g approximately 2 by the magnetic interaction with the Mn cluster, but this interaction collapses at temperatures higher than about 100K [Zahariou et al. (2007) Biochemistry 46, 14335 -14341]. We have conducted a study of the Tyr Z(*) transient in the temperature range 77-240 K by employing rapid or slow EPR scans. The results reveal for the first time high-resolution X-band spectra of Tyr Z(*) in the functional system and at temperatures close to the onset of the S-state transitions. We have simulated the S 2Y Z(*) spectrum using the simulation algorithm of Svistunenko and Cooper [(2004) Biophys. J. 87, 582 -595]. The small g(x) = 2.00689 value inferred from the analysis suggests either a H-bonding of Tyr Z (*) (presumably with His190) that is stronger than what has been assumed from studies of Tyr D(*) or Tyr Z(*) in Mn-depleted preparations or a more electropositive environment around Tyr Z(*). The study has also yielded for the first time direct information on the temperature variation of the YZ(*)/QA(-) recombination reaction in the various S states. The reaction follows biphasic kinetics with the slow phase dominating at low temperatures and the fast phase dominating at high temperatures. It is tentatively proposed that the slow phase represents the action of the YZ(*)/YZ(-) redox couple while the fast phase represents that of the YZ(*)/YZH couple; it is inferred that Tyr Z at elevated temperatures is protonated at rest. It is also proposed that YZ(*)/YZH is the couple that oxidizes the Mn cluster during the S1-S2 and S2-S3 transitions. A simple mechanism ensuring a rapid (concerted) protonation of Tyr Z upon oxidation of the Mn cluster is discussed, and also, a structure-based molecular model suggesting the participation of His190 into two hydrogen bonds is proposed.
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Affiliation(s)
- Nikolaos Ioannidis
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi Attikis, Greece
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31
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Yeagle GJ, Gilchrist ML, McCarrick RM, Britt RD. Multifrequency pulsed electron paramagnetic resonance study of the S2 state of the photosystem II manganese cluster. Inorg Chem 2008; 47:1803-14. [PMID: 18330971 DOI: 10.1021/ic701680c] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Multifrequency electron spin-echo envelope modulation (ESEEM) spectroscopy is employed to measure the strength of the hyperfine coupling of magnetic nuclei to the paramagnetic (S = 1/2) S2 form of photosystem II (PSII). Previous X-band-frequency ESEEM studies indicated that one or more histidine nitrogens are electronically coupled to the tetranuclear manganese cluster in the S2 state of PSII. However, the spectral resolution was relatively poor at the approximately 9 GHz excitation frequency, precluding any in-depth analysis of the corresponding bonding interaction between the detected histidine and the manganese cluster. Here we report ESEEM experiments using higher X-, P-, and Ka-band microwave frequencies to target PSII membranes isolated from spinach. The X- to P-band ESEEM spectra suffer from the same poor resolution as that observed in previous experiments, while the Ka-band spectra show remarkably well-resolved features that allow for the direct determination of the nuclear quadrupolar couplings for a single I = 1(14)N nucleus. The Ka-band results demonstrate that at an applied field of 1.1 T we are much closer to the exact cancellation limit (alpha iso = 2nu(14)N) that optimizes ESEEM spectra. These results reveal hyperfine (alpha iso = 7.3 +/- 0.20 MHz and alpha dip = 0.50 +/- 0.10 MHz) and nuclear quadrupolar (e(2)qQ = 1.98 +/- 0.05 MHz and eta = 0.84 +/- 0.06) couplings for a single (14)N nucleus magnetically coupled to the manganese cluster in the S 2 state of PSII. These values are compared to the histidine imidazole nitrogen hyperfine and nuclear quadrupolar couplings found in superoxidized manganese catalase as well as (14)N couplings in relevant manganese model complexes.
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Affiliation(s)
- Gregory J Yeagle
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, USA
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Pecoraro VL, Hsieh WY. In search of elusive high-valent manganese species that evaluate mechanisms of photosynthetic water oxidation. Inorg Chem 2008; 47:1765-78. [PMID: 18330968 DOI: 10.1021/ic7017488] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Significant progress in the understanding of biological water oxidation has occurred during the past 25 years. Today we have a somewhat clearer description of the structure of the Mn4Ca cluster and an idea of the appropriate oxidation states for the enzyme during catalysis. At issue is the mechanism of water oxidation. Depending on one's belief of the manganese ion oxidation levels at the catalytically active S4 configuration, one can invoke a variety of different processes that could lead to water oxidation. We have suggested that the most likely process is the nucleophilic attack of a water bound to calcium (or manganese) onto a highly electrophilic Mn(V)=O center. In this Article, we explore the difficulties of preparing Mn(V) in dimeric systems and the even more arduous task of definitively assigning oxidation states to such highly reactive species.
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Affiliation(s)
- Vincent L Pecoraro
- Department of Chemistry and Biophysics, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
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33
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González-Pérez S, Quijano C, Romero N, Melø TB, Radi R, Arellano JB. Peroxynitrite inhibits electron transport on the acceptor side of higher plant photosystem II. Arch Biochem Biophys 2008; 473:25-33. [DOI: 10.1016/j.abb.2008.02.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 02/11/2008] [Accepted: 02/16/2008] [Indexed: 01/18/2023]
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34
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Affiliation(s)
- My Hang V Huynh
- DE-1: High Explosive Science and Technology Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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35
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Meyer TJ, Huynh MHV, Thorp HH. The Possible Role of Proton-Coupled Electron Transfer (PCET) in Water Oxidation by Photosystem II. Angew Chem Int Ed Engl 2007; 46:5284-304. [PMID: 17604381 DOI: 10.1002/anie.200600917] [Citation(s) in RCA: 410] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
All higher life forms use oxygen and respiration as their primary energy source. The oxygen comes from water by solar-energy conversion in photosynthetic membranes. In green plants, light absorption in photosystem II (PSII) drives electron-transfer activation of the oxygen-evolving complex (OEC). The mechanism of water oxidation by the OEC has long been a subject of great interest to biologists and chemists. With the availability of new molecular-level protein structures from X-ray crystallography and EXAFS, as well as the accumulated results from numerous experiments and theoretical studies, it is possible to suggest how water may be oxidized at the OEC. An integrated sequence of light-driven reactions that exploit coupled electron-proton transfer (EPT) could be the key to water oxidation. When these reactions are combined with long-range proton transfer (by sequential local proton transfers), it may be possible to view the OEC as an intricate structure that is "wired for protons".
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Affiliation(s)
- Thomas J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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36
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Meyer T, Huynh M, Thorp H. Zur möglichen Rolle des protonengekoppelten Elektronentransfers (PCET) bei der Oxidation von Wasser durch das Photosystem II. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200600917] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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37
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Popelková H, Yocum CF. Current status of the role of Cl(-) ion in the oxygen-evolving complex. PHOTOSYNTHESIS RESEARCH 2007; 93:111-21. [PMID: 17200880 DOI: 10.1007/s11120-006-9121-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 12/04/2006] [Indexed: 05/07/2023]
Abstract
This minireview summarizes the current state of knowledge concerning the role of Cl(-) in the oxygen-evolving complex (OEC) of photosystem II (PSII). The model that proposes that Cl(-) is a Mn ligand is discussed in light of more recent work. Studies of Cl(-) specificity, stoichiometry, kinetics, and retention by extrinsic polypeptides are discussed, as are the results that fail to detect Cl(-) ligation to Mn and results that show a lack of a requirement for Cl(-) in PSII-catalyzed H(2)O oxidation. Mutagenesis experiments in cyanobacteria and higher plants that produce evidence for a correlation between Cl(-) retention and stable interactions among intrinsic and extrinsic polypeptides are summarized, and spectroscopic data on the interaction between PSII and Cl(-) are discussed. Lastly, the question of the site of Cl(-) action in PSII is discussed in connection with the current crystal structures of the enzyme.
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Affiliation(s)
- Hana Popelková
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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38
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Miqyass M, van Gorkom HJ, Yocum CF. The PSII calcium site revisited. PHOTOSYNTHESIS RESEARCH 2007; 92:275-87. [PMID: 17235491 DOI: 10.1007/s11120-006-9124-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 12/08/2006] [Indexed: 05/07/2023]
Abstract
Oxidation of H2O by photosystem II is a unique redox reaction in that it requires Ca2+ as well as Cl- as obligatory activators/cofactors of the reaction, which is catalyzed by Mn atoms. The properties of the binding site for Ca2+ in this reaction resemble those of other Ca2+ binding proteins, and recent X-ray structural data confirm that the metal is in fact ligated at least in part by amino acid side chain oxo anions. Removal of Ca2+ blocks water oxidation chemistry at an early stage in the cycle of redox reactions that result in O-O bond formation, and the intimate involvement of Ca2+ in this reaction that is implied by this result is confirmed by an ever-improving set of crystal structures of the cyanobacterial enzyme. Here, we revisit the photosystem II Ca2+ site, in part to discuss the additional information that has appeared since our earlier review of this subject (van Gorkom HJ, Yocum CF In: Wydrzynski TJ, Satoh K (eds) Photosystem II: the light-driven water:plastoquinone oxidoreductase), and also to reexamine earlier data, which lead us to conclude that all S-state transitions require Ca2+.
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Affiliation(s)
- M Miqyass
- Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, Leiden, RA 2300, The Netherlands
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Haddy A. EPR spectroscopy of the manganese cluster of photosystem II. PHOTOSYNTHESIS RESEARCH 2007; 92:357-68. [PMID: 17551843 DOI: 10.1007/s11120-007-9194-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 05/03/2007] [Indexed: 05/15/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy is a valuable tool for understanding the oxidation state and chemical environment of the Mn4Ca cluster of photosystem II. Since the discovery of the multiline signal from the S2 state, EPR spectroscopy has continued to reveal details about the catalytic center of oxygen evolution. At present EPR signals from nearly all of the S-states of the Mn4Ca cluster, as well as from modified and intermediate states, have been observed. This review article describes the various EPR signals obtained from the Mn4Ca cluster, including the metalloradical signals due to interaction of the cluster with a nearby organic radical.
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Affiliation(s)
- Alice Haddy
- Department of Chemistry and Biochemistry, University of North Carolina at Greensboro, Greensboro, NC 27402, USA.
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40
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Affiliation(s)
- James P McEvoy
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA
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41
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Zhang C. Low-barrier hydrogen bond plays key role in active photosystem II--a new model for photosynthetic water oxidation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1767:493-9. [PMID: 17254545 DOI: 10.1016/j.bbabio.2006.12.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 11/27/2006] [Accepted: 12/14/2006] [Indexed: 10/23/2022]
Abstract
The function and mechanism of Tyr(Z) in active photosystem II (PSII) is one of the long-standing issues in the study of photosynthetic water oxidation. Based on recent investigations on active PSII and theoretical studies, a new model is proposed, in which D1-His190 acts as a bridge, to form a low-barrier hydrogen bond (LBHB) with Tyr(Z), and a coordination bond to Mn or Ca ion of the Mn-cluster. Accordingly, this new model differs from previous proposals concerning the mechanism of Tyr(Z) function in two aspects. First, the LBHB plays a key role to decrease the activation energy for Tyr(Z) oxidation and Tyr(Z)(.) reduction during photosynthetic water oxidation. Upon the oxidation of Tyr(Z), the hydrogen bond between Tyr(Z) and His190 changes from a LBHB to a weak hydrogen bond, and vice versa upon Tyr(Z)(.) reduction. In both stages, the electron transfer and proton transfer are coupled. Second, the positive charge formed after Tyr(Z) oxidation may play an important role for water oxidation. It can be delocalized on the Mn-cluster, thus helps to accelerate the proton release from substrate water on Mn-cluster. This model is well reconciled with observations of the S-state dependence of Tyr(Z) oxidation and Tyr(Z)(.) reduction, proton release, isotopic effect and recent EPR experiments. Moreover, the difference between Tyr(Z) and Tyr(D) in active PSII can also be readily rationalized. The His190 binding to the Mn-cluster predicted in this model is contradictious to the recent structure data, however, it has been aware that the crystal structure of the Mn-cluster and its environment are significantly modified by X-ray due to radiation damage and are different from that in active PSII. It is suggested that the His190 may be protonated during the radiation damage, which leads to the loss of its binding to Mn-cluster and the strong hydrogen bond with Tyr(Z). This type of change arising from radiation damage has been confirmed in other enzyme systems.
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Affiliation(s)
- Chunxi Zhang
- Laboratory of Photochemistry, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
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Noodleman L, Han WG. Structure, redox, pK a, spin. A golden tetrad for understanding metalloenzyme energetics and reaction pathways. J Biol Inorg Chem 2006; 11:674-94. [PMID: 16830148 DOI: 10.1007/s00775-006-0136-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 06/14/2006] [Indexed: 10/24/2022]
Abstract
After a review of the current status of density functional theory (DFT) for spin-polarized and spin-coupled systems, we focus on the resting states and intermediates of redox-active metalloenzymes and electron transfer proteins, showing how comparisons of DFT-calculated spectroscopic parameters with experiment and evaluation of related energies and geometries provide important information. The topics we examine include (1) models for the active-site structure of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X; (2) the coupling of electron transfer to proton transfer in manganese superoxide dismutase, with implications for reaction kinetics; (3) redox, pK(a), and electronic structure issues in the Rieske iron-sulfur protein, including their connection to coupled electron/proton transfer, and an analysis of how partial electron delocalization strongly alters the electron paramagnetic resonance spectrum; (4) the connection between protein-induced structural distortion and the electronic structure of oxidized high-potential 4Fe4S proteins with implications for cluster reactivity; (5) an analysis of cluster assembly and central-atom insertion into the FeMo cofactor center of nitrogenase based on DFT structural and redox potential calculations.
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Affiliation(s)
- Louis Noodleman
- Department of Molecular Biology, TPC15, The Scripps Research Institute, La Jolla, CA 92037, USA.
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43
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Zhang C. Interaction between tyrosineZ and substrate water in active photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:781-6. [PMID: 16843429 DOI: 10.1016/j.bbabio.2006.05.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2005] [Revised: 05/17/2006] [Accepted: 05/18/2006] [Indexed: 11/30/2022]
Abstract
In the field of photosynthetic water oxidation it has been under debate whether Tyrosine(Z) (Tyr(Z)) acts as a hydrogen or an electron acceptor from water. In the former concept, direct contact of Tyr(Z) with substrate water has been assumed. However, there is no direct evidence for the interaction between Tyr(Z) and substrate water in active Photosystem II (PSII), instead most experiments have been performed on inhibited PSII. Here, this problem is tackled in active PSII by combining low temperature EPR measurements and quantum chemistry calculations. EPR measurements observed that the maximum yield of Tyr(Z) oxidation at cryogenic temperature in the S(0) and S(1) states was around neutral pH and was essentially pH-independent. The yield of Tyr(Z) oxidation decreased at acidic and alkaline pH, with pKs at 4.7-4.9 and 7.7, respectively. The observed pH-dependent parts at low and high values of pH can be explained as due to sample inactivation, rather than active PSII. The reduction kinetics of Tyr(Z)(.) in the S(0) and S(1) states were pH independent at pH range from 4.5 to 8. Therefore, the change of the pH in bulk solution probably has no effect on the Tyr(Z) oxidation and Tyr(Z)(.) reduction at cryogenic temperature in the S(0) and S(1) states of the active PSII. Theoretical calculations indicate that Tyr(Z) becomes more difficult to oxidize when a H(2)O molecule interacts directly with it. It is suggested that Tyr(Z) is probably located in a hydrophobic environment with no direct interaction with the substrate H(2)O in active PSII. These results provide new insights on the function and mechanism of water oxidation in PSII.
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Affiliation(s)
- Chunxi Zhang
- Service de Bioénergétique, CNRS URA 2096, Département de Biologie Joliot-Curie, CEA Saclay, Gif-Sur-Yvette, France.
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Liu B, Shen PP, Shi W, Song YG, Li W, Nie Z, Liu Y. Highly efficient photoactivation of Mn-depleted photosystem II by imidazole-liganded manganese complexes. J Biol Inorg Chem 2006; 11:626-32. [PMID: 16791645 DOI: 10.1007/s00775-006-0111-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Accepted: 04/18/2006] [Indexed: 11/26/2022]
Abstract
The oxygen-evolving complex (OEC) of Mn-depleted photosystem II (PSII) can be reconstituted in the presence of exogenous Mn or a Mn complex under weak illumination, a process called photoactivation. Synthetic Mn complexes could provide a powerful system to analyze the assembly of the OEC. In this work, four mononuclear Mn complexes, [(terpy)2Mn(II)(OOCH3)] x 2 H2O (where terpy is 2,2':6',2''-terpyridine), Mn(II)(bzimpy)2, Mn(II)(bp)2(CH3CH2OH)2 [where bzimpy is 2,6-bis(2-benzimidazol-2-yl)pyridine] and [Mn(III)(HL)(L)(py)(CH3OH)]CH3OH (where py is pyridine) were used in photoactivation experiments. Measurements of the photoreduction of 2,6-dichorophenolindophenol and oxygen evolution demonstrate that photoactivation is more efficient when Mn complexes are used instead of MnCl2 in reconstructed PSII preparations. The most efficient recoveries of oxygen evolution and electron transport activities are obtained from a complex, [Mn(III)(HL)(L)(py)(CH3OH)]CH3OH, that contains both imidazole and phenol groups. Its recovery of the rate of oxygen evolution is as high as 79% even in the absence of the 33-kDa peptide. The imidazole ligands of the Mn complex probably accelerate P680*+ reduction and consequently facilitate the process of photoactivation. Also, the strong intermolecular hydrogen bond probably facilitates interaction with the Mn-depleted PSII via reorganization of the hydrogen-bonding network, and therefore promotes the recovery of oxygen evolution and electron transport activities.
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Affiliation(s)
- Bin Liu
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100080, China
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45
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Mino H, Itoh S. The origin of split EPR signals in the Ca2+-depleted photosystem II. PHOTOSYNTHESIS RESEARCH 2005; 84:333-7. [PMID: 16049794 DOI: 10.1007/s11120-005-0476-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2004] [Accepted: 01/12/2005] [Indexed: 05/03/2023]
Abstract
A light-driven reaction model for the Ca2+-depleted Photosystem (PS) II is proposed to explain the split signal observed in electron paramagnetic resonance (EPR) spectra based on a comparison of EPR assignments with recent x-ray structural data. The split signal has a splitting linewidth of 160 G at around g = 2 and is seen upon illumination of the Ca2+-depleted PS II in the S2 state associated with complete or partial disappearance of the S2 state multiline signal. Another g=2 broad ESR signal with a 110 G linewidth was produced by 245 K illumination for a short period in the Ca2+-depleted PS II in S1 state. At the same time a normal YZ . radical signal was also efficiently trapped. The g=2 broad signal is attributed to an intermediate S1X. state in equilibrium with the trapped YZ . radical. Comparison with x-ray structural data suggests that one of the split signals (doublet signal) is attributable to interaction between His 190 and the YZ . radical, and other signals is attributable to interaction between His 337 and the manganese cluster, providing further clues as to the mechanism of water oxidation in photosynthetic oxygen evolution.
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Affiliation(s)
- Hiroyuki Mino
- Division of Material Science (Physics), Graduate school of Science, Nagoya University, Furou, Chikusa, Nagoya 464-8602, Japan.
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Mino H, Itoh S. EPR properties of a g=2 broad signal trapped in an S1 state in Ca2+-depleted Photosystem II. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1708:42-9. [PMID: 15949982 DOI: 10.1016/j.bbabio.2005.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2004] [Revised: 12/18/2004] [Accepted: 01/06/2005] [Indexed: 11/19/2022]
Abstract
We investigated a new EPR signal that gives a broad line shape around g=2 in Ca(2+)-depleted Photosystem (PS) II. The signal was trapped by illumination at 243 K in parallel with the formation of Y(Z)*. The ratio of the intensities between the g=2 broad signal and the Y(Z)* signal was 1:3, assuming a Gaussian line shape for the former. The g=2 broad signal and the Y(Z)* signal decayed together in parallel with the appearance of the S(2) state multiline at 243 K. The g=2 broad signal was assigned to be an intermediate S(1)X* state in the transition from the S(1) to the S(2) state, where X* represents an amino acid radical nearby manganese cluster, such as D1-His337. The signal is in thermal equilibrium with Y(Z)*. Possible reactions in the S state transitions in Ca(2+)-depleted PS II were discussed.
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Affiliation(s)
- Hiroyuki Mino
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocyo, Chikusa, Nagoya 464-8602, Japan.
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47
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Berthomieu C, Hienerwadel R. Vibrational spectroscopy to study the properties of redox-active tyrosines in photosystem II and other proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1707:51-66. [PMID: 15721606 DOI: 10.1016/j.bbabio.2004.03.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Accepted: 03/31/2004] [Indexed: 11/27/2022]
Abstract
Tyrosine radicals play catalytic roles in essential metalloenzymes. Their properties--midpoint potential, stability...--or environment varies considerably from one enzyme to the other. To understand the origin of these properties, the redox tyrosines are studied by a number of spectroscopic techniques, including Fourier transform infrared (FTIR) and resonance Raman (RR) spectroscopy. An increasing number of vibrational data are reported for the (modified-) redox active tyrosines in ribonucleotide reductases, photosystem II, heme catalase and peroxidases, galactose and glyoxal oxidases, and cytochrome oxidase. The spectral markers for the tyrosinyl radicals have been recorded on models of (substituted) phenoxyl radicals, free or coordinated to metals. We review these vibrational data and present the correlations existing between the vibrational modes of the radicals and their properties and interactions formed with their environment: we present that the nu7a(C-O) mode of the radical, observed both by RR and FTIR spectroscopy at 1480-1515 cm(-1), is a sensitive marker of the hydrogen bonding status of (substituted)-phenoxyl and Tyr*, while the nu8a(C-C) mode may probe coordination of the Tyr* to a metal. For photosystem II, the information obtained by light-induced FTIR difference spectroscopy for the two redox tyrosines TyrD and TyrZ and their hydrogen bonding partners is discussed in comparison with those obtained by other spectroscopic methods.
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Affiliation(s)
- Catherine Berthomieu
- CEA-Cadarache, Laboratoire de Bioénergétique Cellulaire, UMR 6191 CNRS-CEA-Aix-Marseille II, Univ.-Méditerranée CEA 1000, Bât. 156, F-13108 Saint-Paul-lez-Durance, Cedex, France.
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48
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van Gorkom HJ, Yocum CF. The Calcium and Chloride Cofactors. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2005. [DOI: 10.1007/1-4020-4254-x_14] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Kim SH, Gregor W, Peloquin JM, Brynda M, Britt RD. Investigation of the calcium-binding site of the oxygen evolving complex of photosystem II using 87Sr ESEEM spectroscopy. J Am Chem Soc 2004; 126:7228-37. [PMID: 15186160 DOI: 10.1021/ja030614e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The proximity of the calcium/strontium binding site of the oxygen evolving complex (OEC) of photosystem II (PSII) to the paramagnetic Mn cluster is explored with (87)Sr three-pulse electron spin-echo envelope modulation (ESEEM) spectroscopy. CW-EPR spectra of Sr(2+)-substituted Ca(2+)-depleted PSII membranes show the modified g = 2 multiline EPR signal as previously reported. We performed three-pulse ESEEM on this modified multiline signal of the Mn cluster using natural abundance Sr and (87)Sr, respectively. Three-pulse ESEEM of the natural abundance Sr sample exhibits no detectable modulation by the 7% abundance (87)Sr. On the other hand, that of the (87)Sr enriched (93%) sample clearly reveals modulation arising from the I = (9)/(2) (87)Sr nucleus weakly magnetically coupled to the Mn cluster. Using a simple point dipole approximation for the electron spin, analysis of the (87)Sr ESEEM modulation depth via an analytic expression suggests a Mn-Ca (Sr) distance of 4.5 A. Simulation of three-pulse ESEEM with a numerical matrix diagonalization procedure gave good agreement with this analytical result. A more appropriate tetranuclear magnetic/structural model for the Mn cluster converts the 4.5 A point dipole distance to a 3.8-5.0 A range of distances. DFT calculations of (43)Ca and (87)Sr quadrupolar interactions on Ca (and Sr substituted) binding sites in various proteins suggest that the lack of the nuclear quadrupole induced splitting in the ESEEM spectrum of (87)Sr enriched PSII samples is related to a very high degree of symmetry of the ligands surrounding the Sr(2+) ion in the substituted Ca site. Numerical simulations show that moderate (87)Sr quadrupolar couplings decrease the envelope modulation relative to the zero quadrupole case, and therefore we consider that the 3.8-5.0 A range obtained without quadrupolar coupling included in the simulation represents an upper limit to the actual manganese-calcium distance. This (87)Sr pulsed EPR spectroscopy provides independent direct evidence that the calcium/strontium binding site is close to the Mn cluster in the OEC of PSII.
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Affiliation(s)
- Sun Hee Kim
- Department of Chemistry, University of California, Davis, California 95616, USA
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50
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MacBeth CE, Gupta R, Mitchell-Koch KR, Young VG, Lushington GH, Thompson WH, Hendrich MP, Borovik AS. Utilization of hydrogen bonds to stabilize M-O(H) units: synthesis and properties of monomeric iron and manganese complexes with terminal oxo and hydroxo ligands. J Am Chem Soc 2004; 126:2556-67. [PMID: 14982465 DOI: 10.1021/ja0305151] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Non-heme iron and manganese species with terminal oxo ligands are proposed to be key intermediates in a variety of biological and synthetic systems; however, the stabilization of these types of complexes has proven difficult because of the tendency to form oxo-bridged complexes. Described herein are the design, isolation, and properties for a series of mononuclear Fe(III) and Mn(III) complexes with terminal oxo or hydroxo ligands. Isolation of the complexes was facilitated by the tripodal ligand tris[(N'-tert-butylureaylato)-N-ethyl]aminato ([H(3)1](3-)), which creates a protective hydrogen bond cavity around the M(III)-O(H) units (M(III) = Fe and Mn). The M(III)-O(H) complexes are prepared by the activation of dioxygen and deprotonation of water. In addition, the M(III)-O(H) complexes can be synthesized using oxygen atom transfer reagents such as N-oxides and hydroxylamines. The [Fe(III)H(3)1(O)](2-) complex also can be made using sulfoxides. These findings support the proposal of a high valent M(IV)-oxo species as an intermediate during dioxygen cleavage. Isotopic labeling studies show that oxo ligands in the [M(III)H(3)1(O)](2-) complexes come directly from the cleavage of dioxygen: for [Fe(III)H(3)1(O)](2-) the nu(Fe-(16)O) = 671 cm(-1), which shifts 26 cm(-1) in [Fe(III)H(3)1((18)O)](2-) (nu(Fe-(18)O) = 645 cm(-1)); a nu(Mn-(16)O) = 700 cm(-1) was observed for [Mn(III)H(3)1((16)O)](2-), which shifts to 672 cm(-1) in the Mn-(18)O isotopomer. X-ray diffraction studies show that the Fe-O distance is 1.813(3) A in [Fe(III)H(3)1(O)](2-), while a longer bond is found in [Fe(III)H(3)1(OH)](-) (Fe-O at 1.926(2) A); a similar trend was found for the Mn(III)-O(H) complexes, where a Mn-O distance of 1.771(5) A is observed for [Mn(III)H(3)1(O)](2-) and 1.873(2) A for [Mn(III)H(3)1(OH)](-). Strong intramolecular hydrogen bonds between the urea NH groups of [H(3)1](3-) and the oxo and oxygen of the hydroxo ligand are observed in all the complexes. These findings, along with density functional theory calculations, indicate that a single sigma-bond exists between the M(III) centers and the oxo ligands, and additional interactions to the oxo ligands arise from intramolecular H-bonds, which illustrates that noncovalent interactions may replace pi-bonds in stabilizing oxometal complexes.
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Affiliation(s)
- Cora E MacBeth
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA
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