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Kalendra V, Reiss KM, Banerjee G, Ghosh I, Baldansuren A, Batista VS, Brudvig GW, Lakshmi KV. Binding of the substrate analog methanol in the oxygen-evolving complex of photosystem II in the D1-N87A genetic variant of cyanobacteria. Faraday Discuss 2022; 234:195-213. [PMID: 35147155 DOI: 10.1039/d1fd00094b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solar water-splitting protein complex, photosystem II (PSII), catalyzes one of the most energetically demanding reactions in nature by using light energy to drive a catalyst capable of oxidizing water. The water oxidation reaction is catalyzed at the Mn4Ca-oxo cluster in the oxygen-evolving complex (OEC), which cycles through five light-driven S-state intermediates (S0-S4). A detailed mechanism of the reaction remains elusive as it requires knowledge of the delivery and binding of substrate water in the higher S-state intermediates. In this study, we use two-dimensional (2D) hyperfine sublevel correlation spectroscopy, in conjunction with quantum mechanics/molecular mechanics (QM/MM) and density functional theory (DFT), to probe the binding of the substrate analog, methanol, in the S2 state of the D1-N87A variant of PSII from Synechocystis sp. PCC 6803. The results indicate that the size and specificity of the "narrow" channel is altered in D1-N87A PSII, allowing for the binding of deprotonated 13C-labeled methanol at the Mn4(IV) ion of the catalytic cluster in the S2 state. This has important implications on the mechanistic models for water oxidation in PSII.
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Affiliation(s)
- Vidmantas Kalendra
- Department of Chemistry and Chemical Biology, The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA.
| | - Krystle M Reiss
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520, USA.
| | - Gourab Banerjee
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520, USA.
| | - Ipsita Ghosh
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520, USA.
| | - Amgalanbaatar Baldansuren
- Department of Chemistry and Chemical Biology, The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA.
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520, USA.
| | - Gary W Brudvig
- Department of Chemistry, Yale University, New Haven, Connecticut, 06520, USA.
| | - K V Lakshmi
- Department of Chemistry and Chemical Biology, The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA.
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2
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Gorka MJ, Baldansuren A, Malnati A, Gruszecki E, Golbeck JH, Lakshmi K. Shedding light on primary donors in photosynthetic reaction centers. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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3
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Bonitatibus PJ, Alvarez S, Armstrong WH, Baldansuren A, Gaspard ME, Lakshmi KV, Ziegler MS, Charles P. Synthesis, Crystal Structure, EPR, and DFT Studies of an Unusually Distorted Vanadium(II) Complex. Dalton Trans 2022; 51:12031-12036. [DOI: 10.1039/d2dt02392j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a synthesis and structure of the most highly distorted four-coordinate d3 ion known to date that also serves as the second known example of a bis(biphenolato) transition metal...
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4
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Gorka M, Baldansuren A, Malnati A, Gruszecki E, Golbeck JH, Lakshmi KV. Shedding Light on Primary Donors in Photosynthetic Reaction Centers. Front Microbiol 2021; 12:735666. [PMID: 34659164 PMCID: PMC8517396 DOI: 10.3389/fmicb.2021.735666] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 08/30/2021] [Indexed: 11/17/2022] Open
Abstract
Chlorophylls (Chl)s exist in a variety of flavors and are ubiquitous in both the energy and electron transfer processes of photosynthesis. The functions they perform often occur on the ultrafast (fs-ns) time scale and until recently, these have been difficult to measure in real time. Further, the complexity of the binding pockets and the resulting protein-matrix effects that alter the respective electronic properties have rendered theoretical modeling of these states difficult. Recent advances in experimental methodology, computational modeling, and emergence of new reaction center (RC) structures have renewed interest in these processes and allowed researchers to elucidate previously ambiguous functions of Chls and related pheophytins. This is complemented by a wealth of experimental data obtained from decades of prior research. Studying the electronic properties of Chl molecules has advanced our understanding of both the nature of the primary charge separation and subsequent electron transfer processes of RCs. In this review, we examine the structures of primary electron donors in Type I and Type II RCs in relation to the vast body of spectroscopic research that has been performed on them to date. Further, we present density functional theory calculations on each oxidized primary donor to study both their electronic properties and our ability to model experimental spectroscopic data. This allows us to directly compare the electronic properties of hetero- and homodimeric RCs.
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Affiliation(s)
- Michael Gorka
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States
| | - Amgalanbaatar Baldansuren
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Amanda Malnati
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Elijah Gruszecki
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - John H. Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States
- Department of Chemistry, The Pennsylvania State University, University Park, PA, United States
| | - K. V. Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch ’60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY, United States
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5
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Gorka M, Charles P, Kalendra V, Baldansuren A, Lakshmi KV, Golbeck JH. A dimeric chlorophyll electron acceptor differentiates type I from type II photosynthetic reaction centers. iScience 2021; 24:102719. [PMID: 34278250 PMCID: PMC8267441 DOI: 10.1016/j.isci.2021.102719] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 05/17/2021] [Accepted: 06/09/2021] [Indexed: 01/09/2023] Open
Abstract
This research addresses one of the most compelling issues in the field of photosynthesis, namely, the role of the accessory chlorophyll molecules in primary charge separation. Using a combination of empirical and computational methods, we demonstrate that the primary acceptor of photosystem (PS) I is a dimer of accessory and secondary chlorophyll molecules, Chl2A and Chl3A, with an asymmetric electron charge density distribution. The incorporation of highly coupled donors and acceptors in PS I allows for extensive delocalization that prolongs the lifetime of the charge-separated state, providing for high quantum efficiency. The discovery of this motif has widespread implications ranging from the evolution of naturally occurring reaction centers to the development of a new generation of highly efficient artificial photosynthetic systems. Video abstract
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Affiliation(s)
- Michael Gorka
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Philip Charles
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Vidmantas Kalendra
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Amgalanbaatar Baldansuren
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - K V Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.,Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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Lakshmi K, Mendez-Hernandez DD, Baldansuren A, Kalendra V, Charles P, Mark B, Marshall W, Molnar B, Moore TA, Moore AL. Understanding the Mechanism of Proton-Coupled Electron Transfer in the Bioinspired Artificial Photosynthetic Mimic, Benzimidazole Phenol Porphyrin. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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7
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Méndez-Hernández DD, Baldansuren A, Kalendra V, Charles P, Mark B, Marshall W, Molnar B, Moore TA, Lakshmi KV, Moore AL. HYSCORE and DFT Studies of Proton-Coupled Electron Transfer in a Bioinspired Artificial Photosynthetic Reaction Center. iScience 2020; 23:101366. [PMID: 32738611 PMCID: PMC7394912 DOI: 10.1016/j.isci.2020.101366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 06/22/2020] [Accepted: 07/10/2020] [Indexed: 11/24/2022] Open
Abstract
The photosynthetic water-oxidation reaction is catalyzed by the oxygen-evolving complex in photosystem II (PSII) that comprises the Mn4CaO5 cluster, with participation of the redox-active tyrosine residue (YZ) and a hydrogen-bonded network of amino acids and water molecules. It has been proposed that the strong hydrogen bond between YZ and D1-His190 likely renders YZ kinetically and thermodynamically competent leading to highly efficient water oxidation. However, a detailed understanding of the proton-coupled electron transfer (PCET) at YZ remains elusive owing to the transient nature of its intermediate states involving YZ⋅. Herein, we employ a combination of high-resolution two-dimensional 14N hyperfine sublevel correlation spectroscopy and density functional theory methods to investigate a bioinspired artificial photosynthetic reaction center that mimics the PCET process involving the YZ residue of PSII. Our results underscore the importance of proximal water molecules and charge delocalization on the electronic structure of the artificial reaction center. Structural factors are critical in the design of artificial photosynthetic systems Correlation between hyperfine couplings of the N atoms and electron spin density Spin density distribution affected by charge delocalization and explicit waters Spin density modulation by electronic coupling as observed with P680 and YZ in PSII
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Affiliation(s)
| | - Amgalanbaatar Baldansuren
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Vidmantas Kalendra
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Philip Charles
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Brian Mark
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - William Marshall
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Brian Molnar
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - K V Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
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8
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Pask CM, Greatorex S, Kulmaczewski R, Baldansuren A, McInnes EJL, Bamiduro F, Yamada M, Yoshinari N, Konno T, Halcrow MA. Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin-Crossover Compound From its Copper(II) and Zinc(II) Congeners. Chemistry 2020; 26:4833-4841. [PMID: 32017244 DOI: 10.1002/chem.202000101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Indexed: 11/12/2022]
Abstract
Annealing [FeL2 ][BF4 ]2 ⋅2 H2 O (L=2,6-bis-[5-methyl-1H-pyrazol-3-yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T1/2 =205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL2 ][BF4 ]2 ⋅2 H2 O and [ZnL2 ][BF4 ]2 ⋅2 H2 O are not perfectly isostructural but, unlike the iron compound, they undergo single-crystal-to-single-crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re-cooling. The low-temperature phase of [CuL2 ][BF4 ]2 involves ordering of its Jahn-Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low-temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high-spin iron compound, before the onset of spin-crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper-doped [Fe0.97 Cu0.03 L2 ][BF4 ]2 imply its low-spin phase contains two distinct cation environments in a 2:1 ratio.
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Affiliation(s)
- Christopher M Pask
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Sam Greatorex
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Amgalanbaatar Baldansuren
- School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,current address: Chemistry and Chemical Biology, 120 Cogswell, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY, 12180, USA
| | - Eric J L McInnes
- School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Faith Bamiduro
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Mihoko Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.,current address: Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
| | - Nobuto Yoshinari
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Takumi Konno
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.,Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
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9
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Korzyński MD, Braglia L, Borfecchia E, Lomachenko KA, Baldansuren A, Hendon CH, Lamberti C, Dincă M. Quo vadis niobium? Divergent coordination behavior of early-transition metals towards MOF-5. Chem Sci 2019; 10:5906-5910. [PMID: 31360395 PMCID: PMC6566296 DOI: 10.1039/c9sc01553a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/07/2019] [Indexed: 12/17/2022] Open
Abstract
Treatment of MOF-5 with NbCl4(THF)2 in acetonitrile leads to incorporation of Nb(iv) centers in a fashion that diverges from the established cation metathesis reactivity of this iconic material. A combination of X-ray absorption spectroscopy analysis and reactivity studies altogether supported by density functional theory computational studies document an unprecedented binding mode for the Zn4O(O2C-)6 secondary building units (SBUs), which in Nb(iv)-MOF-5 function as κ 2-chelating ligands for NbCl4 moieties, with no exchange of Zn2+ observed. This unusual reactivity expands the portfolio of post-synthetic modification techniques available for MOFs, exemplified here by MOF-5, and underscores the diverse coordination environments offered by this and potentially other MOFs towards heterometal species.
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Affiliation(s)
- Maciej D Korzyński
- Department of Chemistry , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , MA 02139 , USA .
| | - Luca Braglia
- CNR-Istituto Officina dei Materiali , TASC Laboratory in Area Science Park - Basovizza , Strada Statale 14 km 163.5 , 34149 Trieste , Italy
| | - Elisa Borfecchia
- Department of Chemistry , NIS , CrisDi , INSTM Centre of Reference , University of Turin , Via Quarello 15 , I-10135 Torino , Italy
- Center for Materials Science and Nanotechnology (SMN) , Department of Chemistry , University of Oslo , 1033 Blindern , 0315 Oslo , Norway
| | - Kirill A Lomachenko
- European Synchrotron Radiation Facility , 71 Avenue des Martyrs, CS 40220 , 38043 Grenoble Cedex 9 , France
| | - Amgalanbaatar Baldansuren
- EPSRC National EPR Facility , School of Chemistry , The University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Christopher H Hendon
- Materials Science Institute , Department of Chemistry and Biochemistry , University of Oregon , Eugene , Oregon 97403 , USA
| | - Carlo Lamberti
- Department of Physics , NIS , CrisDi , Interdepartmental Centers , INSTM Centre of Reference , University of Turin , Via Giuria 1 , I-10125 Torino , Italy
- The Smart Materials Research Institute , Southern Federal University , 178/24 Sladkova Street , Rostov-on-Don , 344090 , Russia
| | - Mircea Dincă
- Department of Chemistry , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , MA 02139 , USA .
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10
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Greatorex S, Vincent KB, Baldansuren A, McInnes EJL, Patmore NJ, Sproules S, Halcrow MA. Rigidification of a macrocyclic tris-catecholate scaffold leads to electronic localisation of its mixed valent redox product. Chem Commun (Camb) 2019; 55:2281-2284. [DOI: 10.1039/c8cc10122a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
One-electron oxidation of the compound shown shows no evidence for intervalence charge transfer in the macrocylic ligand radical product. In contrast, related [{Pt(L)}3(μ3-ctc˙)]+ (H6ctc = cyclotricatechylene), exhibits class II mixed valency.
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Affiliation(s)
- Sam Greatorex
- School of Chemistry
- University of Leeds
- Leeds LS2 9JT
- UK
| | - Kevin B. Vincent
- Department of Chemical Sciences
- University of Huddersfield
- Huddersfield HD1 3DH
- UK
| | | | - Eric J. L. McInnes
- School of Chemistry and Photon Science Institute
- University of Manchester
- Manchester M13 9PL
- UK
| | - Nathan J. Patmore
- Department of Chemical Sciences
- University of Huddersfield
- Huddersfield HD1 3DH
- UK
| | - Stephen Sproules
- WestCHEM, School of Chemistry
- University of Glasgow
- Glasgow G12 8QQ
- UK
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11
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Sanz S, O'Connor HM, Comar P, Baldansuren A, Pitak MB, Coles SJ, Weihe H, Chilton NF, McInnes EJL, Lusby PJ, Piligkos S, Brechin EK. Modular [Fe III8M II6] n+ (M II = Pd, Co, Ni, Cu) Coordination Cages. Inorg Chem 2018; 57:3500-3506. [PMID: 29323893 DOI: 10.1021/acs.inorgchem.7b02674] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The reaction of the simple metalloligand [FeIIIL3] [HL = 1-(4-pyridyl)butane-1,3-dione] with a variety of different MII salts results in the formation of a family of heterometallic cages of formulae [FeIII8PdII6L24]Cl12 (1), [FeIII8CuII6L24(H2O)4Br4]Br8 (2), [FeIII8CuII6L24(H2O)10](NO3)12 (3), [FeIII8NiII6L24(SCN)11Cl] (4), and [FeIII8CoII6L24(SCN)10(H2O)2]Cl2 (5). The metallic skeleton of each cage describes a cube in which the FeIII ions occupy the eight vertices and the MII ions lie at the center of the six faces. Direct-current magnetic susceptibility and magnetization measurements on 3-5 reveal the presence of weak antiferromagnetic exchange between the metal ions in all three cases. Computational techniques known in theoretical nuclear physics as statistical spectroscopy, which exploit the moments of the Hamiltonian to calculate relevant thermodynamic properties, determine JFe-Cu = 0.10 cm-1 for 3 and JFe-Ni = 0.025 cm-1 for 4. Q-band electron paramagnetic resonance spectra of 1 reveal a significantly wider spectral width in comparison to [FeL3], indicating that the magnitude of the FeIII zero-field splitting is larger in the heterometallic cage than in the monomer.
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Affiliation(s)
- Sergio Sanz
- EaStCHEM School of Chemistry , University of Edinburgh , David Brewster Road , Edinburgh EH9 3FJ , U.K
| | - Helen M O'Connor
- EaStCHEM School of Chemistry , University of Edinburgh , David Brewster Road , Edinburgh EH9 3FJ , U.K
| | - Priyanka Comar
- EaStCHEM School of Chemistry , University of Edinburgh , David Brewster Road , Edinburgh EH9 3FJ , U.K
| | - Amgalanbaatar Baldansuren
- Engineering and Physical Sciences Research Council (EPSRC) National Electron Paramagnetic Resonance (EPR) Facility, School of Chemistry and Photon Science Institute , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Mateusz B Pitak
- UK National Crystallography Service, Chemistry , University of Southampton , Highfield Campus , Southampton SO17 1BJ , U.K
| | - Simon J Coles
- UK National Crystallography Service, Chemistry , University of Southampton , Highfield Campus , Southampton SO17 1BJ , U.K
| | - Høgni Weihe
- Department of Chemistry , University of Copenhagen , Universitetsparken 5 , Copenhagen DK-2100 , Denmark
| | - Nicholas F Chilton
- Engineering and Physical Sciences Research Council (EPSRC) National Electron Paramagnetic Resonance (EPR) Facility, School of Chemistry and Photon Science Institute , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Eric J L McInnes
- Engineering and Physical Sciences Research Council (EPSRC) National Electron Paramagnetic Resonance (EPR) Facility, School of Chemistry and Photon Science Institute , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Paul J Lusby
- EaStCHEM School of Chemistry , University of Edinburgh , David Brewster Road , Edinburgh EH9 3FJ , U.K
| | - Stergios Piligkos
- Department of Chemistry , University of Copenhagen , Universitetsparken 5 , Copenhagen DK-2100 , Denmark
| | - Euan K Brechin
- EaStCHEM School of Chemistry , University of Edinburgh , David Brewster Road , Edinburgh EH9 3FJ , U.K
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Abstract
A family of heterometallic Anderson-type ‘wheels’ of general formula [MIII2MII5(hmp)12]4+ has been extended to include MIII = Cr, Al; MII = Co, Ni, Fe, Mn, Cu and Zn, alongside the ‘extended’ [AlIII6CuII7(OH)12(hmp)12]8+.
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Affiliation(s)
| | - Gary S. Nichol
- EaStCHEM School of Chemistry
- The University of Edinburgh
- Edinburgh
- UK
| | | | - Eric J. L. McInnes
- School of Chemistry and Photon Science Institute
- The University of Manchester
- Manchester
- UK
| | - Euan K. Brechin
- EaStCHEM School of Chemistry
- The University of Edinburgh
- Edinburgh
- UK
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13
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Taguchi AT, Miyajima-Nakano Y, Fukazawa R, Lin MT, Baldansuren A, Gennis RB, Hasegawa K, Kumasaka T, Dikanov SA, Iwasaki T. Unpaired Electron Spin Density Distribution across Reduced [2Fe-2S] Cluster Ligands by 13Cβ-Cysteine Labeling. Inorg Chem 2017; 57:741-746. [DOI: 10.1021/acs.inorgchem.7b02676] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexander T. Taguchi
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Yoshiharu Miyajima-Nakano
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Risako Fukazawa
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | | | - Amgalanbaatar Baldansuren
- Department of Veterinary
Clinical Medicine, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Robert B. Gennis
- Department of Biochemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Kazuya Hasegawa
- Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Sayo, Hyogo 679-5198, Japan
| | - Takashi Kumasaka
- Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Sayo, Hyogo 679-5198, Japan
| | - Sergei A. Dikanov
- Department of Veterinary
Clinical Medicine, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Toshio Iwasaki
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
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14
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Griffiths K, Tsipis AC, Kumar P, Townrow OPE, Abdul-Sada A, Akien GR, Baldansuren A, Spivey AC, Kostakis GE. 3d/4f Coordination Clusters as Cooperative Catalysts for Highly Diastereoselective Michael Addition Reactions. Inorg Chem 2017; 56:9563-9573. [DOI: 10.1021/acs.inorgchem.7b01011] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kieran Griffiths
- Department of Chemistry,
School of Life Sciences, University of Sussex, Brighton BN1 9QJ, U.K
| | - Athanassios C. Tsipis
- Laboratory of Inorganic and General Chemistry,
Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece
| | - Prashant Kumar
- Department of Chemistry,
School of Life Sciences, University of Sussex, Brighton BN1 9QJ, U.K
| | - Oliver P. E. Townrow
- Department of Chemistry,
School of Life Sciences, University of Sussex, Brighton BN1 9QJ, U.K
| | - Alaa Abdul-Sada
- Department of Chemistry,
School of Life Sciences, University of Sussex, Brighton BN1 9QJ, U.K
| | - Geoffrey R. Akien
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K
| | | | - Alan C. Spivey
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - George E. Kostakis
- Department of Chemistry,
School of Life Sciences, University of Sussex, Brighton BN1 9QJ, U.K
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15
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Sanz S, O'Connor HM, Martí-Centelles V, Comar P, Pitak MB, Coles SJ, Lorusso G, Palacios E, Evangelisti M, Baldansuren A, Chilton NF, Weihe H, McInnes EJL, Lusby PJ, Piligkos S, Brechin EK. [MIII2MII3] n+ trigonal bipyramidal cages based on diamagnetic and paramagnetic metalloligands. Chem Sci 2017; 8:5526-5535. [PMID: 28970932 PMCID: PMC5618769 DOI: 10.1039/c7sc00487g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/18/2017] [Indexed: 11/24/2022] Open
Abstract
A family of five [MIII2MII3] n+ trigonal bipyramidal cages (MIII = Fe, Cr and Al; MII = Co, Zn and Pd; n = 0 for 1-3 and n = 6 for 4-5) of formulae [Fe2Co3L6Cl6] (1), [Fe2Zn3L6Br6] (2), [Cr2Zn3L6Br6] (3), [Cr2Pd3L6(dppp)3](OTf)6 (4) and [Al2Pd3L6(dppp)3](OTf)6 (5) (where HL is 1-(4-pyridyl)butane-1,3-dione and dppp is 1,3-bis(diphenylphosphino)propane) are reported. Neutral cages 1-3 were synthesised using the tritopic [MIIIL3] metalloligand in combination with the salts CoIICl2 and ZnIIBr2, which both act as tetrahedral linkers. The assembly of the cis-protected [PdII(dppp)(OTf)2] with [MIIIL3] afforded the anionic cages 4-5 of general formula [MIII2PdII3](OTf)6. The metallic skeleton of all cages describes a trigonal bipyramid with the MIII ions occupying the two axial sites and the MII ions sitting in the three equatorial positions. Direct current (DC) magnetic susceptibility, magnetisation and heat capacity measurements on 1 reveal weak antiferromagnetic exchange between the FeIII and CoII ions. EPR spectroscopy demonstrates that the distortion imposed on the {MO6} coordination sphere of [MIIIL3] by complexation in the {MIII2MII3} supramolecules results in a small, but measurable, increase of the zero field splitting at MIII. Complete active space self-consistent field (CASSCF) calculations on the three unique CoII sites of 1 suggest DCo ≈ -14 cm-1 and E/D ≈ 0.1, consistent with the magnetothermal and spectroscopic data.
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Affiliation(s)
- S Sanz
- EaStCHEM School of Chemistry , The University of Edinburgh , David Brewster Road , Edinburgh , EH9 3FJ , UK . ; ;
| | - H M O'Connor
- EaStCHEM School of Chemistry , The University of Edinburgh , David Brewster Road , Edinburgh , EH9 3FJ , UK . ; ;
| | - V Martí-Centelles
- EaStCHEM School of Chemistry , The University of Edinburgh , David Brewster Road , Edinburgh , EH9 3FJ , UK . ; ;
| | - P Comar
- EaStCHEM School of Chemistry , The University of Edinburgh , David Brewster Road , Edinburgh , EH9 3FJ , UK . ; ;
| | - M B Pitak
- UK National Crystallography Service , Chemistry , University of Southampton , Highfield Campus , Southampton , SO17 1BJ , UK
| | - S J Coles
- UK National Crystallography Service , Chemistry , University of Southampton , Highfield Campus , Southampton , SO17 1BJ , UK
| | - G Lorusso
- Instituto de Ciencia de Materiales de Aragón (ICMA) , CSIC - Universidad de Zaragoza , Departamento de Física de la Materia Condensada , 50009 Zaragoza , Spain
| | - E Palacios
- Instituto de Ciencia de Materiales de Aragón (ICMA) , CSIC - Universidad de Zaragoza , Departamento de Física de la Materia Condensada , 50009 Zaragoza , Spain
| | - M Evangelisti
- Instituto de Ciencia de Materiales de Aragón (ICMA) , CSIC - Universidad de Zaragoza , Departamento de Física de la Materia Condensada , 50009 Zaragoza , Spain
| | - A Baldansuren
- School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
| | - N F Chilton
- School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
| | - H Weihe
- Department of Chemistry , University of Copenhagen , Universitetsparken 5 , DK-2100 , Copenhagen , Denmark .
| | - E J L McInnes
- School of Chemistry , The University of Manchester , Oxford Road , Manchester , M13 9PL , UK .
| | - P J Lusby
- EaStCHEM School of Chemistry , The University of Edinburgh , David Brewster Road , Edinburgh , EH9 3FJ , UK . ; ;
| | - S Piligkos
- Department of Chemistry , University of Copenhagen , Universitetsparken 5 , DK-2100 , Copenhagen , Denmark .
| | - E K Brechin
- EaStCHEM School of Chemistry , The University of Edinburgh , David Brewster Road , Edinburgh , EH9 3FJ , UK . ; ;
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16
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Abstract
The formation mechanism and bonding in a rare vanadocene complex with N-heterocyclic silylene (1,3-bis(2,6-diisopropylphenyl)-1,3-diaza-2-silacyclopent-4-en-2-ylidene) is elucidated using a combination of experimental and theoretical techniques.
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Affiliation(s)
- Mikko M. Hänninen
- School of Chemistry
- The University of Manchester
- Manchester
- UK
- Department of Chemistry
| | | | - Thomas Pugh
- School of Chemistry
- The University of Manchester
- Manchester
- UK
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17
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Taguchi AT, Baldansuren A, Dikanov SA. Basic and Combination Cross-Features in X- and Q-band HYSCORE of the 15N Labeled Bacteriochlorophyll a Cation Radical. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/zpch-2016-0815] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Chlorophylls are an essential class of cofactors found in all photosynthetic organisms. Upon absorbing a photon, the excited state energy of the chlorophyll can either be transferred to another acceptor molecule, or be used to drive electron transfer. When acting as the primary donor in the bacterial photosynthetic reaction center, light-induced charge separation results in the formation of a cationic bacteriochlorophyll dimer. The hyperfine interactions between the unpaired electron of the 15N labeled bacteriochlorophyll cation radical and its four pyrrole nitrogens are probed with X- and Q-band 15N HYSCORE spectroscopy in frozen solution. The powder-type HYSCORE shows the basic (ν
α(β), ν
β(α)) cross-features as well as several types of combination cross-features. The nitrogen tensors were resolved in the squared-frequency representation of the HYSCORE spectra, and simulations of the combination peaks allowed for further refinement of the hyperfine coupling constants. The nitrogen tensors were found to have coupling constants a=3.28 MHz, T=1.23 MHz (N1 and N2), a=4.10 MHz, T=1.25 MHz (N3), and a=4.35 MHz, T=1.70 MHz (N4). The combination features were assigned based on a linear regression analysis of the cross-ridges in the squared-frequency representation as well as spectral simulations. The methodology discussed here will provide an important foundation for analyzing and understanding complex two-dimensional spectra from several I=1/2 nuclei.
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Affiliation(s)
- Alexander T. Taguchi
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Amgalanbaatar Baldansuren
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sergei A. Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA , Phone: +(217) 300-2209
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18
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Hua C, Baldansuren A, Tuna F, Collison D, D'Alessandro DM. In Situ Spectroelectrochemical Investigations of the Redox-Active Tris[4-(pyridin-4-yl)phenyl]amine Ligand and a Zn(2+) Coordination Framework. Inorg Chem 2016; 55:7270-80. [PMID: 27419690 DOI: 10.1021/acs.inorgchem.6b00981] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An investigation of the redox-active tris[4-(pyridin-4-yl)phenyl]amine (NPy3) ligand in the solution state and upon its incorporation into the solid-state metal-organic framework (MOF) [Zn(NPy3)(NO2)2·xMeOH·xDMF]n (MeOH = methanol and DMF = N,N-dimethylformamide) was conducted using in situ UV/vis/near-IR, electron paramagentic resonance (EPR), and fluorescence spectroelectrochemical experiments. Through this multifaceted approach, the properties of the ligand and framework were elucidated and quantified as a function of the redox state of the triarylamine core, which can undergo a one-electron oxidation to its radical cation. The use of pulsed EPR experiments revealed that the radical generated was highly delocalized throughout the entire ligand backbone. This combination of techniques provides comprehensive insight into electronic delocalization in a framework system and demonstrates the utility of in situ spectroelectrochemical methods in assessing electroactive MOFs.
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Affiliation(s)
- Carol Hua
- School of Chemistry, The University of Sydney , Sydney, New South Wales 2006, Australia
| | - Amgalanbaatar Baldansuren
- School of Chemistry and Photon Science Institute, The University of Manchester , Manchester M13 9PL, United Kingdom
| | - Floriana Tuna
- School of Chemistry and Photon Science Institute, The University of Manchester , Manchester M13 9PL, United Kingdom
| | - David Collison
- School of Chemistry and Photon Science Institute, The University of Manchester , Manchester M13 9PL, United Kingdom
| | - Deanna M D'Alessandro
- School of Chemistry, The University of Sydney , Sydney, New South Wales 2006, Australia
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19
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Frandsen KEH, Simmons TJ, Dupree P, Poulsen JCN, Hemsworth GR, Ciano L, Johnston EM, Tovborg M, Johansen KS, von Freiesleben P, Marmuse L, Fort S, Cottaz S, Driguez H, Henrissat B, Lenfant N, Tuna F, Baldansuren A, Davies GJ, Lo Leggio L, Walton PH. The molecular basis of polysaccharide cleavage by lytic polysaccharide monooxygenases. Nat Chem Biol 2016; 12:298-303. [PMID: 26928935 DOI: 10.1038/nchembio.2029] [Citation(s) in RCA: 221] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/12/2016] [Indexed: 12/27/2022]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are copper-containing enzymes that oxidatively break down recalcitrant polysaccharides such as cellulose and chitin. Since their discovery, LPMOs have become integral factors in the industrial utilization of biomass, especially in the sustainable generation of cellulosic bioethanol. We report here a structural determination of an LPMO-oligosaccharide complex, yielding detailed insights into the mechanism of action of these enzymes. Using a combination of structure and electron paramagnetic resonance spectroscopy, we reveal the means by which LPMOs interact with saccharide substrates. We further uncover electronic and structural features of the enzyme active site, showing how LPMOs orchestrate the reaction of oxygen with polysaccharide chains.
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Affiliation(s)
| | - Thomas J Simmons
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Paul Dupree
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | | | - Luisa Ciano
- Department of Chemistry, University of York, York, UK
| | | | | | | | | | - Laurence Marmuse
- Centre de Recherches sur les Macromolecules Végétales (CERMAV), Université de Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Grenoble, France
| | - Sébastien Fort
- Centre de Recherches sur les Macromolecules Végétales (CERMAV), Université de Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Grenoble, France
| | - Sylvain Cottaz
- Centre de Recherches sur les Macromolecules Végétales (CERMAV), Université de Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Grenoble, France
| | - Hugues Driguez
- Centre de Recherches sur les Macromolecules Végétales (CERMAV), Université de Grenoble Alpes, Centre National de la Recherche Scientifique (CNRS), Grenoble, France
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques (AFMB), CNRS, Aix-Marseille Université, Marseille, France.,Institut National de la Recherche Agronomique (INRA), AFMB, Marseille, France.,Department of Biological Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Nicolas Lenfant
- Architecture et Fonction des Macromolécules Biologiques (AFMB), CNRS, Aix-Marseille Université, Marseille, France.,Institut National de la Recherche Agronomique (INRA), AFMB, Marseille, France
| | - Floriana Tuna
- Engineering and Physical Sciences Research Council (EPSRC) National EPR Facility, School of Chemistry and Photon Science Institute, University of Manchester, Manchester, UK
| | - Amgalanbaatar Baldansuren
- Engineering and Physical Sciences Research Council (EPSRC) National EPR Facility, School of Chemistry and Photon Science Institute, University of Manchester, Manchester, UK
| | | | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Paul H Walton
- Department of Chemistry, University of York, York, UK
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20
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Loughrey JJ, Patmore NJ, Baldansuren A, Fielding AJ, McInnes EJL, Hardie MJ, Sproules S, Halcrow MA. Platinum(ii) complexes of mixed-valent radicals derived from cyclotricatechylene, a macrocyclic tris-dioxolene. Chem Sci 2015; 6:6935-6948. [PMID: 29861932 PMCID: PMC5951140 DOI: 10.1039/c5sc02776d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 08/18/2015] [Indexed: 01/10/2023] Open
Abstract
Three complexes of cyclotricatechylene (H6ctc), [{PtL}3(μ3-ctc)], have been synthesised: (L = 1,2-bis(diphenylphosphino)benzene {dppb}, 1; L = 1,2-bis(diphenylphosphino)ethane {dppe}, 2; L = 4,4'-bis(tert-butyl)-2,2'-bipyridyl { t Bu2bipy}, 3). The complexes show three low-potential, chemically reversible voltammetric oxidations separated by ca. 180 mV, corresponding to stepwise oxidation of the [ctc]6- catecholato rings to the semiquinonate level. The redox series [1]0/1+/2+/3+ and [3]0/1+/2+/3+ have been characterised by UV/vis/NIR spectroelectrochemistry. The mono- and di-cations have class II mixed valent character, with reduced radical delocalisation compared to an analogous bis-dioxolene system. The SOMO composition of [1˙]+ and [3˙]+ has been delineated by cw EPR, ENDOR and HYSCORE spectroscopies, with the aid of two monometallic model compounds [PtL(DBsq˙)]+ (DBsqH = 3,5-bis(tert-butyl)-1,2-benzosemiquinone; L = dppe or t Bu2bipy). DF and time-dependent DF calculations confirm these interpretations, and demonstrate changes to spin-delocalisation in the ctc macrocycle as it is sequentially oxidised.
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Affiliation(s)
- Jonathan J Loughrey
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , UK .
| | - Nathan J Patmore
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK
| | - Amgalanbaatar Baldansuren
- School of Chemistry and Photon Science Institute , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Alistair J Fielding
- School of Chemistry and Photon Science Institute , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Eric J L McInnes
- School of Chemistry and Photon Science Institute , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Michaele J Hardie
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , UK .
| | - Stephen Sproules
- WestCHEM , School of Chemistry , University of Glasgow , Glasgow G12 8QQ , UK .
| | - Malcolm A Halcrow
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , UK .
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21
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Murray AT, Dowley MJH, Pradaux-Caggiano F, Baldansuren A, Fielding AJ, Tuna F, Hendon CH, Walsh A, Lloyd-Jones GC, John MP, Carbery DR. Catalytic Amine Oxidation under Ambient Aerobic Conditions: Mimicry of Monoamine Oxidase B. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201503654] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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22
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Murray AT, Dowley MJH, Pradaux-Caggiano F, Baldansuren A, Fielding AJ, Tuna F, Hendon CH, Walsh A, Lloyd-Jones GC, John MP, Carbery DR. Catalytic Amine Oxidation under Ambient Aerobic Conditions: Mimicry of Monoamine Oxidase B. Angew Chem Int Ed Engl 2015; 54:8997-9000. [PMID: 26087676 PMCID: PMC4524416 DOI: 10.1002/anie.201503654] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Indexed: 11/10/2022]
Abstract
The flavoenzyme monoamine oxidase (MAO) regulates mammalian behavioral patterns by modulating neurotransmitters such as adrenaline and serotonin. The mechanistic basis which underpins this enzyme is far from agreed upon. Reported herein is that the combination of a synthetic flavin and alloxan generates a catalyst system which facilitates biomimetic amine oxidation. Mechanistic and electron paramagnetic (EPR) spectroscopic data supports the conclusion that the reaction proceeds through a radical manifold. This data provides the first example of a biorelevant synthetic model for monoamine oxidase B activity.
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Affiliation(s)
| | - Myles J H Dowley
- Department of Chemistry, University of Bath, Claverton Down, Bath (UK)
| | | | - Amgalanbaatar Baldansuren
- EPSRC National EPR Facility, Photon Science Institute, School of Chemistry, University of Manchester, Oxford Road, Manchester (UK)
| | - Alistair J Fielding
- EPSRC National EPR Facility, Photon Science Institute, School of Chemistry, University of Manchester, Oxford Road, Manchester (UK)
| | - Floriana Tuna
- EPSRC National EPR Facility, Photon Science Institute, School of Chemistry, University of Manchester, Oxford Road, Manchester (UK)
| | | | - Aron Walsh
- Department of Chemistry, University of Bath, Claverton Down, Bath (UK)
| | - Guy C Lloyd-Jones
- School of Chemistry, Joseph Black Building, West Mains Road, Edinburgh EH9 3 JJ (UK)
| | - Matthew P John
- GlaxoSmithKline Research and Development, Gunnels Wood Road, Stevenage (UK)
| | - David R Carbery
- Department of Chemistry, University of Bath, Claverton Down, Bath (UK).
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23
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Xue B, Chow JY, Baldansuren A, Yap LL, Gan YH, Dikanov SA, Robinson RC, Yew WS. Structural evidence of a productive active site architecture for an evolved quorum-quenching GKL lactonase. Biochemistry 2013; 52:2359-70. [PMID: 23461395 DOI: 10.1021/bi4000904] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The in vitro evolution and engineering of quorum-quenching lactonases with enhanced reactivities was achieved using a thermostable GKL enzyme as a template, yielding the E101G/R230C GKL mutant with increased catalytic activity and a broadened substrate range [Chow, J. Y., Xue, B., Lee, K. H., Tung, A., Wu, L., Robinson, R. C., and Yew, W. S. (2010) J. Biol. Chem. 285, 40911-40920]. This enzyme possesses the (β/α)8-barrel fold and is a member of the PLL (phosphotriesterase-like lactonase) group of enzymes within the amidohydrolase superfamily that hydrolyze N-acyl-homoserine lactones, which mediate the quorum-sensing pathways of bacteria. The structure of the evolved N-butyryl-l-homoserine lactone (substrate)-bound E101G/R230C GKL enzyme was determined, in the presence of the inactivating D266N mutation, to a resolution of 2.2 Å to provide an explanation for the observed rate enhancements. In addition, the substrate-bound structure of the catalytically inactive E101N/D266N mutant of the manganese-reconstituted enzyme was determined to a resolution of 2.1 Å and the structure of the ligand-free, manganese-reconstituted E101N mutant to a resolution of 2.6 Å, and the structures of ligand-free zinc-reconstituted wild-type, E101N, R230D, and E101G/R230C mutants of GKL were determined to resolutions of 2.1, 2.1, 1.9, and 2.0 Å, respectively. In particular, the structure of the evolved E101G/R230C mutant of GKL provides evidence of a catalytically productive active site architecture that contributes to the observed enhancement of catalysis. At high concentrations, wild-type and mutant GKL enzymes are differentially colored, with absorbance maxima in the range of 512-553 nm. The structures of the wild-type and mutant GKL provide a tractable link between the origins of the coloration and the charge-transfer complex between the α-cation and Tyr99 within the enzyme active site. Taken together, this study provides evidence of the modulability of enzymatic catalysis through subtle changes in enzyme active site architecture.
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Affiliation(s)
- Bo Xue
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673
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24
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Xue B, Chow JY, Baldansuren A, Yap LL, Gan YH, Dikanov SA, Robinson RC, Yew WS. Correction to "Structural evidence of a productive active site architecture for an evolved quorum-quenching GKL lactonase". Biochemistry 2013; 51:10120. [PMID: 23088324 DOI: 10.1021/bi3011829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Iwasaki T, Fukazawa R, Miyajima-Nakano Y, Baldansuren A, Matsushita S, Lin MT, Gennis RB, Hasegawa K, Kumasaka T, Dikanov SA. Dissection of hydrogen bond interaction network around an iron-sulfur cluster by site-specific isotope labeling of hyperthermophilic archaeal Rieske-type ferredoxin. J Am Chem Soc 2012; 134:19731-8. [PMID: 23145461 DOI: 10.1021/ja308049u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The electronic structure and geometry of redox-active metal cofactors in proteins are tuned by the pattern of hydrogen bonding with the backbone peptide matrix. In this study we developed a method for selective amino acid labeling of a hyperthermophilic archaeal metalloprotein with engineered Escherichia coli auxotroph strains, and we applied this to resolve the hydrogen bond interactions with the reduced Rieske-type [2Fe-2S] cluster by two-dimensional pulsed electron spin resonance technique. Because deep electron spin-echo envelope modulation of two histidine (14)N(δ) ligands of the cluster decreased non-coordinating (15)N signal intensities via the cross-suppression effect, an inverse labeling strategy was employed in which (14)N amino acid-labeled archaeal Rieske-type ferredoxin samples were examined in an (15)N-protein background. This has directly identified Lys45 N(α) as providing the major pathway for the transfer of unpaired electron spin density from the reduced cluster by a "through-bond" mechanism. All other backbone peptide nitrogens interact more weakly with the reduced cluster. The extension of this approach will allow visualizing the three-dimensional landscape of preferred pathways for the transfer of unpaired spin density from a paramagnetic metal center onto the protein frame, and will discriminate specific interactions by a "through-bond" mechanism from interactions which are "through-space" in various metalloproteins.
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Affiliation(s)
- Toshio Iwasaki
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan.
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26
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Martin E, Baldansuren A, Lin TJ, Samoilova RI, Wraight CA, Dikanov SA, O'Malley PJ. Hydrogen bonding between the Q(B) site ubisemiquinone and Ser-L223 in the bacterial reaction center: a combined spectroscopic and computational perspective. Biochemistry 2012; 51:9086-93. [PMID: 23016832 DOI: 10.1021/bi300834w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the Q(B) site of the Rhodobacter sphaeroides photosynthetic reaction center, the donation of a hydrogen bond from the hydroxyl group of Ser-L223 to the ubisemiquinone formed after the first flash is debatable. In this study, we use a combination of spectroscopy and quantum mechanics/molecular mechanics (QM/MM) calculations to comprehensively explore this topic. We show that ENDOR, ESEEM, and HYSCORE spectroscopic differences between mutant L223SA and the wild-type sample (WT) are negligible, indicating only minor perturbations in the ubisemiquinone spin density for the mutant sample. Qualitatively, this suggests that a strong hydrogen bond does not exist in the WT between the Ser-L223 hydroxyl group and the semiquinone O(1) atom, as removal of this hydrogen bond in the mutant should cause a significant redistribution of spin density in the semiquinone. We show quantitatively, using QM/MM calculations, that a WT model in which the Ser-L223 hydroxyl group is rotated to prevent hydrogen bond formation with the O(1) atom of the semiquinone predicts negligible change for the L223SA mutant. This, together with the better agreement between key QM/MM calculated and experimental hyperfine couplings for the non-hydrogen-bonded model, leads us to conclude that no strong hydrogen bond is formed between the Ser-L223 hydroxyl group and the semiquinone O(1) atom after the first flash. The implications of this finding for quinone reduction in photosynthetic reaction centers are discussed.
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Affiliation(s)
- Erik Martin
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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Lin MT, Baldansuren A, Hart R, Samoilova RI, Narasimhulu KV, Yap LL, Choi SK, O'Malley PJ, Gennis RB, Dikanov SA. Interactions of intermediate semiquinone with surrounding protein residues at the Q(H) site of wild-type and D75H mutant cytochrome bo3 from Escherichia coli. Biochemistry 2012; 51:3827-38. [PMID: 22497216 DOI: 10.1021/bi300151q] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selective (15)N isotope labeling of the cytochrome bo(3) ubiquinol oxidase from Escherichia coli with auxotrophs was used to characterize the hyperfine couplings with the side-chain nitrogens from residues R71, H98, and Q101 and peptide nitrogens from residues R71 and H98 around the semiquinone (SQ) at the high-affinity Q(H) site. The two-dimensional ESEEM (HYSCORE) data have directly identified N(ε) of R71 as an H-bond donor carrying the largest amount of unpaired spin density. In addition, weaker hyperfine couplings with the side-chain nitrogens from all residues around the SQ were determined. These hyperfine couplings reflect a distribution of the unpaired spin density over the protein in the SQ state of the Q(H) site and the strength of interaction with different residues. The approach was extended to the virtually inactive D75H mutant, where the intermediate SQ is also stabilized. We found that N(ε) of a histidine residue, presumably H75, carries most of the unpaired spin density instead of N(ε) of R71, as in wild-type bo(3). However, the detailed characterization of the weakly coupled (15)N atoms from selective labeling of R71 and Q101 in D75H was precluded by overlap of the (15)N lines with the much stronger ~1.6 MHz line from the quadrupole triplet of the strongly coupled (14)N(ε) atom of H75. Therefore, a reverse labeling approach, in which the enzyme was uniformly labeled except for selected amino acid types, was applied to probe the contribution of R71 and Q101 to the (15)N signals. Such labeling has shown only weak coupling with all nitrogens of R71 and Q101. We utilize density functional theory-based calculations to model the available information about (1)H, (15)N, and (13)C hyperfine couplings for the Q(H) site and to describe the protein-substrate interactions in both enzymes. In particular, we identify the factors responsible for the asymmetric distribution of the unpaired spin density and ponder the significance of this asymmetry to the quinone's electron transfer function.
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Affiliation(s)
- Myat T Lin
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Lin MT, Shubin AA, Samoilova RI, Narasimhulu KV, Baldansuren A, Gennis RB, Dikanov SA. Exploring by pulsed EPR the electronic structure of ubisemiquinone bound at the QH site of cytochrome bo3 from Escherichia coli with in vivo 13C-labeled methyl and methoxy substituents. J Biol Chem 2011; 286:10105-14. [PMID: 21247900 PMCID: PMC3060462 DOI: 10.1074/jbc.m110.206821] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 01/13/2011] [Indexed: 11/06/2022] Open
Abstract
The cytochrome bo(3) ubiquinol oxidase from Escherichia coli resides in the bacterial cytoplasmic membrane and catalyzes the two-electron oxidation of ubiquinol-8 and four-electron reduction of O(2) to water. The one-electron reduced semiquinone forms transiently during the reaction, and the enzyme has been demonstrated to stabilize the semiquinone. The semiquinone is also formed in the D75E mutant, where the mutation has little influence on the catalytic activity, and in the D75H mutant, which is virtually inactive. In this work, wild-type cytochrome bo(3) as well as the D75E and D75H mutant proteins were prepared with ubiquinone-8 (13)C-labeled selectively at the methyl and two methoxy groups. This was accomplished by expressing the proteins in a methionine auxotroph in the presence of l-methionine with the side chain methyl group (13)C-labeled. The (13)C-labeled quinone isolated from cytochrome bo(3) was also used for the generation of model anion radicals in alcohol. Two-dimensional pulsed EPR and ENDOR were used for the study of the (13)C methyl and methoxy hyperfine couplings in the semiquinone generated in the three proteins indicated above and in the model system. The data were used to characterize the transferred unpaired spin densities on the methyl and methoxy substituents and the conformations of the methoxy groups. In the wild type and D75E mutant, the constraints on the configurations of the methoxy side chains are similar, but the D75H mutant appears to have altered methoxy configurations, which could be related to the perturbed electron distribution in the semiquinone and the loss of enzymatic activity.
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Affiliation(s)
| | | | - Rimma I. Samoilova
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Kuppala V. Narasimhulu
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 and
| | | | | | - Sergei A. Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 and
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Baldansuren A, Eichel RA, Roduner E. Nitrogen oxide reaction with six-atom silver clusters supported on LTA zeolite. Phys Chem Chem Phys 2009; 11:6664-75. [DOI: 10.1039/b903870a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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