151
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Zhong W, Wu L, Jiang W, Li Y, Mookan N, Liu X. Proton-coupled electron transfer in the reduction of diiron hexacarbonyl complexes and its enhancement on the electrocatalytic reduction of protons by a pendant basic group. Dalton Trans 2019; 48:13711-13718. [DOI: 10.1039/c9dt02058f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The pendant basic groups in a diiron complex acted as proton relay to ease the kinetic resistance in proton reduction and enhance proton-coupled electron transfer (PCET).
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Affiliation(s)
- Wei Zhong
- College of Biological
- Chemical Sciences and Engineering
- Jiaxing University
- Jiaxing 314001
- China
| | - Li Wu
- College of Biological
- Chemical Sciences and Engineering
- Jiaxing University
- Jiaxing 314001
- China
| | - Weidong Jiang
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Yulong Li
- Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan
- Sichuan University of Science & Engineering
- Zigong
- China
| | - Natarajan Mookan
- College of Biological
- Chemical Sciences and Engineering
- Jiaxing University
- Jiaxing 314001
- China
| | - Xiaoming Liu
- College of Biological
- Chemical Sciences and Engineering
- Jiaxing University
- Jiaxing 314001
- China
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152
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Pannwitz A, Wenger OS. Recent advances in bioinspired proton-coupled electron transfer. Dalton Trans 2019; 48:5861-5868. [DOI: 10.1039/c8dt04373f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Fundamental aspects of PCET continue to attract attention. Understanding this reaction type is desirable for small-molecule activation and solar energy conversion.
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Affiliation(s)
- Andrea Pannwitz
- Department of Chemistry
- University of Basel
- 4056 Basel
- Switzerland
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153
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Wild U, Hübner O, Greb L, Enders M, Kaifer E, Himmel HJ. Twofold Oxidized and Twofold Protonated Redox-Active Guanidine: An Ultimate Intermediate in Proton-Coupled Electron-Transfer Reactions. European J Org Chem 2018. [DOI: 10.1002/ejoc.201801378] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ute Wild
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Olaf Hübner
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Lutz Greb
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Markus Enders
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
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154
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Xu Y, Bao P, Song K, Shi Q. Theoretical study of proton coupled electron transfer reaction in the light state of the AppA BLUF photoreceptor. J Comput Chem 2018; 40:1005-1014. [PMID: 30341953 DOI: 10.1002/jcc.25561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/01/2018] [Accepted: 07/24/2018] [Indexed: 11/10/2022]
Abstract
The BLUF (blue light sensor using flavin adenine dinucleotide) domain is widely studied as a prototype for proton coupled electron transfer (PCET) reactions in biological systems. In this work, the photo-induced concerted PCET reaction from the light state of the AppA BLUF domain is investigated. To model the simultaneous transfer of two protons in the reaction, two-dimensional potential energy surfaces for the double proton transfer are first calculated for the locally excited and charge transfer states, which are then used to obtain the vibrational wave function overlaps and the vibrational energy levels. Contributions to the PCET rate constant from each pair of vibronic states are then analyzed using the theory based on the Fermi's golden rule. We show that, the recently proposed light state structure of the BLUF domain with a tautomerized Gln63 residue is consistent with the concerted transfer of one electron and two protons. It is also found that, thermal fluctuations of the protein structure, especially the proton donor-acceptor distances, play an important role in determining the PCET reaction rate. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Yang Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Peng Bao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Kai Song
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qiang Shi
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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155
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Bezdek MJ, Chirik PJ. Proton-Coupled Electron Transfer to a Molybdenum Ethylene Complex Yields a β-Agostic Ethyl: Structure, Dynamics and Mechanism. J Am Chem Soc 2018; 140:13817-13826. [DOI: 10.1021/jacs.8b08460] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Máté J. Bezdek
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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156
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Sarma T, Kim G, Sen S, Cha WY, Duan Z, Moore MD, Lynch VM, Zhang Z, Kim D, Sessler JL. Proton-Coupled Redox Switching in an Annulated π-Extended Core-Modified Octaphyrin. J Am Chem Soc 2018; 140:12111-12119. [PMID: 30180553 DOI: 10.1021/jacs.8b06938] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Proton-coupled electron transfer (PCET) is an important chemical and biological phenomenon. It is attractive as an on-off switching mechanism for redox-active synthetic systems but has not been extensively exploited for this purpose. Here we report a core-modified planar weakly antiaromatic/nonaromatic octaphyrin, namely, a [32]octaphyrin(1.0.1.0.1.0.1.0) (1) derived from rigid naphthobipyrrole and dithienothiophene (DTT) precursors, that undergoes proton-coupled two-electron reduction to produce its aromatic congener in the presence of HCl and other hydrogen halides. Evidence for the production of a [4 n + 1] π-electron intermediate radical state is seen in the presence of trifluoroacetic acid. Electrochemical analyses provide support for the notion that protonation causes a dramatic anodic shift in the reduction potentials of octaphyrin 1, thereby facilitating electron transfer from halide anions (viz. I-, Br-, and, Cl-). Electron-rich molecules, such as tetrathiafulvene (TTF), phenothiazine (PTZ), and catechol, were also found to induce PCET in the case of 1. Both the oxidized and two-electron reduced forms of 1 were characterized by X-ray diffraction analyses in the solid state and in solution via spectroscopic means.
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Affiliation(s)
- Tridib Sarma
- Center for Supramolecular Chemistry & Catalysis , Shanghai University , Shanghai 200444 , China.,Department of Chemistry , The University of Texas at Austin , 105 East 24th Street, Stop A5300 , Austin , Texas 78712-1224 , United States
| | - Gakhyun Kim
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems , Yonsei University , Seoul 03722 , Korea
| | - Sajal Sen
- Department of Chemistry , The University of Texas at Austin , 105 East 24th Street, Stop A5300 , Austin , Texas 78712-1224 , United States
| | - Won-Young Cha
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems , Yonsei University , Seoul 03722 , Korea
| | - Zhiming Duan
- Center for Supramolecular Chemistry & Catalysis , Shanghai University , Shanghai 200444 , China
| | - Matthew D Moore
- Department of Chemistry , The University of Texas at Austin , 105 East 24th Street, Stop A5300 , Austin , Texas 78712-1224 , United States
| | - Vincent M Lynch
- Department of Chemistry , The University of Texas at Austin , 105 East 24th Street, Stop A5300 , Austin , Texas 78712-1224 , United States
| | - Zhan Zhang
- Center for Supramolecular Chemistry & Catalysis , Shanghai University , Shanghai 200444 , China
| | - Dongho Kim
- Department of Chemistry and Spectroscopy Laboratory for Functional π-Electronic Systems , Yonsei University , Seoul 03722 , Korea
| | - Jonathan L Sessler
- Center for Supramolecular Chemistry & Catalysis , Shanghai University , Shanghai 200444 , China.,Department of Chemistry , The University of Texas at Austin , 105 East 24th Street, Stop A5300 , Austin , Texas 78712-1224 , United States
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157
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Yang L, Chen X, Qu Z, Gao J. Combined Multistate and Kohn-Sham Density Functional Theory Studies of the Elusive Mechanism of N-Dealkylation of N,N-Dimethylanilines Mediated by the Biomimetic Nonheme Oxidant Fe IV(O)(N4Py)(ClO 4) 2. Front Chem 2018; 6:406. [PMID: 30250841 PMCID: PMC6139341 DOI: 10.3389/fchem.2018.00406] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 08/20/2018] [Indexed: 11/13/2022] Open
Abstract
The oxidative C-H bond activation mediated by heme and nonheme enzymes and related biomimetics is one of the most interesting processes in bioinorganic and oxidative chemistry. However, the mechanisms of these reactions are still elusive and controversy due to the involvement of highly reactive metal-oxo intermediates with multiple spin states, despite extensive experimental efforts, especially for the N-dealkylation of N,N-dialkyalinines. In this work, we employed multistate density functional theory (MSDFT) and the Kohn-Sham DFT to investigate the mechanism of N-demethylation of N,N-dimethyalinines oxidized by the reaction intermediate FeIV(O)(N4Py)(ClO4)2. The Kohn-Sham DFT study demonstrated that the reaction proceeds via a rate-limiting hydrogen atom transfer (HAT) step and a subsequent barrier-free oxygen rebound step to form the carbinol product. The MSDFT investigation on the first C-H activation further showed that this step is an initial hydrogen atom abstraction that is highly correlated between CEPT and HAT, i.e., both CEPT and HAT processes make significant contributions to the mechanism before reaching the diabatic crossing point, then the valence bond character of the adiabatic ground state is switched to the CEPT product configuration. The findings from this work may be applicable to other hydrogen abstraction process.
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Affiliation(s)
- Lili Yang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Xin Chen
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Zexing Qu
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Jiali Gao
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China.,Department of Chemistry, University of Minnesota, Minneapolis, MN, United States
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158
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Drolen C, Conklin E, Hetterich SJ, Krishnamurthy A, Andrade GA, Dimeglio JL, Martin MI, Tran LK, Yap GPA, Rosenthal J, Young ER. pH-Driven Mechanistic Switching from Electron Transfer to Energy Transfer between [Ru(bpy) 3] 2+ and Ferrocene Derivatives. J Am Chem Soc 2018; 140:10169-10178. [PMID: 30070469 PMCID: PMC6192533 DOI: 10.1021/jacs.8b03933] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The metal-to-ligand charge transfer excited states of [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) may be deactivated via energy transfer or electron transfer with ferrocene derivatives in aqueous conditions. Stern-Volmer quenching analysis revealed that the rate constant for [Ru(bpy)3]2+ excited-state quenching depends on solution pH when a ferrocenyl-amidinium derivative (Fc-am) containing a proton-responsive functionality tethered to the ferrocene center was present. By contrast, the rate constant with which the [Ru(bpy)3]2+ excited state is quenched by an analogous ferrocene derivative (ferrocenyl-trimethylammonium, Fc-mam) that lacks a protonic group does not depend on pH. These results show that the presence (or absence) of a readily transferrable proton modulates quenching rate constants in bimolecular events involving [Ru(bpy)3]2+ and ferrocene. More surprisingly, transient absorption spectroscopy reveals that the mechanism by which the [Ru(bpy)3]2+ excited state is quenched by Fc-am appears to be modulated by solution proton availability, switching from energy transfer at low pH when Fc-am is protonated, to electron transfer at high pH when Fc-am is deprotonated. The mechanistic switching that is observed for this system cannot be aptly explained using a simple driving force dependence argument, suggesting that more subtle factors dictate the pathway by which the [Ru(bpy)3]2+ excited state is deactivated by ferrocene in aqueous solutions.
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Affiliation(s)
- Claire Drolen
- Department of Chemistry, Amherst College, Merrill Science Building, Amherst, Massachusetts 01002, United States
| | - Eric Conklin
- Department of Chemistry, Amherst College, Merrill Science Building, Amherst, Massachusetts 01002, United States
| | - Stephen J. Hetterich
- Department of Chemistry, Amherst College, Merrill Science Building, Amherst, Massachusetts 01002, United States
| | - Aditi Krishnamurthy
- Department of Chemistry, Amherst College, Merrill Science Building, Amherst, Massachusetts 01002, United States
| | - Gabriel A. Andrade
- Department of Chemistry and Biochemistry, Brown Laboratory, University of Delaware, Newark, Delaware 19716, United States
| | - John L. Dimeglio
- Department of Chemistry and Biochemistry, Brown Laboratory, University of Delaware, Newark, Delaware 19716, United States
| | - Maxwell I. Martin
- Department of Chemistry and Biochemistry, Brown Laboratory, University of Delaware, Newark, Delaware 19716, United States
| | - Linh K. Tran
- Department of Chemistry and Biochemistry, Brown Laboratory, University of Delaware, Newark, Delaware 19716, United States
| | - Glenn P. A. Yap
- Department of Chemistry and Biochemistry, Brown Laboratory, University of Delaware, Newark, Delaware 19716, United States
| | - Joel Rosenthal
- Department of Chemistry and Biochemistry, Brown Laboratory, University of Delaware, Newark, Delaware 19716, United States
| | - Elizabeth R. Young
- Department of Chemistry, Amherst College, Merrill Science Building, Amherst, Massachusetts 01002, United States
- Department of Chemistry, Lehigh University, Seeley G. Mudd Building, Bethlehem, Pennsylvania, 18015, United States
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159
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van Niekerk DME, Gerber WJ. A DFT Mechanistic Study of the trans-[Os VIO 2(OH) 4] 2– and [Os VIIIO 4(OH) n] n− ( n = 1, 2 cis) Comproportionation Proton-Coupled Electron Transfer Reaction. Inorg Chem 2018; 57:8909-8922. [DOI: 10.1021/acs.inorgchem.8b00840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniël M. E. van Niekerk
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Stellenbosch, 7602 Western Cape, South Africa
| | - Wilhelmus J. Gerber
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Stellenbosch, 7602 Western Cape, South Africa
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160
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Peters JW, Beratan DN, Bothner B, Dyer RB, Harwood CS, Heiden ZM, Hille R, Jones AK, King PW, Lu Y, Lubner CE, Minteer SD, Mulder DW, Raugei S, Schut GJ, Seefeldt LC, Tokmina-Lukaszewska M, Zadvornyy OA, Zhang P, Adams MW. A new era for electron bifurcation. Curr Opin Chem Biol 2018; 47:32-38. [PMID: 30077080 DOI: 10.1016/j.cbpa.2018.07.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/16/2018] [Accepted: 07/18/2018] [Indexed: 11/17/2022]
Abstract
Electron bifurcation, or the coupling of exergonic and endergonic oxidation-reduction reactions, was discovered by Peter Mitchell and provides an elegant mechanism to rationalize and understand the logic that underpins the Q cycle of the respiratory chain. Thought to be a unique reaction of respiratory complex III for nearly 40 years, about a decade ago Wolfgang Buckel and Rudolf Thauer discovered that flavin-based electron bifurcation is also an important component of anaerobic microbial metabolism. Their discovery spawned a surge of research activity, providing a basis to understand flavin-based bifurcation, forging fundamental parallels with Mitchell's Q cycle and leading to the proposal of metal-based bifurcating enzymes. New insights into the mechanism of electron bifurcation provide a foundation to establish the unifying principles and essential elements of this fascinating biochemical phenomenon.
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Affiliation(s)
- John W Peters
- Institute of Biological Chemistry, Washington State University, Pullman WA 99163, United States; Pacific Northwest National Laboratory, Richland, WA 99352, United States.
| | - David N Beratan
- Department of Chemistry and Department of Physics, Duke University, Durham, NC 27708, United States; Department of Biochemistry, Duke University, Durham, NC 27710, United States
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - R Brian Dyer
- Department of Chemistry, Emory University, Atlanta, GA 30322, United States
| | - Caroline S Harwood
- Department of Microbiology, University of Washington, Seattle, WA 98195, United States
| | - Zachariah M Heiden
- Department of Chemistry, Washington State University, Pullman WA 99163, United States
| | - Russ Hille
- Biochemistry Department, University of California at Riverside, Riverside, CA 92521, United States
| | - Anne K Jones
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, United States
| | - Paul W King
- National Renewable Energy Laboratory, Golden, CO 8040, United States
| | - Yi Lu
- Pacific Northwest National Laboratory, Richland, WA 99352, United States; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Carolyn E Lubner
- National Renewable Energy Laboratory, Golden, CO 8040, United States
| | - Shelley D Minteer
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, United States
| | - David W Mulder
- National Renewable Energy Laboratory, Golden, CO 8040, United States
| | - Simone Raugei
- Institute of Biological Chemistry, Washington State University, Pullman WA 99163, United States; Pacific Northwest National Laboratory, Richland, WA 99352, United States
| | - Gerrit J Schut
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602, United States
| | - Lance C Seefeldt
- Pacific Northwest National Laboratory, Richland, WA 99352, United States; Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, United States
| | | | - Oleg A Zadvornyy
- Institute of Biological Chemistry, Washington State University, Pullman WA 99163, United States
| | - Peng Zhang
- Department of Biochemistry, Duke University, Durham, NC 27710, United States
| | - Michael Ww Adams
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602, United States
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161
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Meng K, Medina-Ramos J, Yibeltal-Ashenafi E, Alvarez JC. Interplay of proton and electron transfer to determine concerted behavior in the proton-coupled electron transfer of glutathione oxidation. Phys Chem Chem Phys 2018; 20:17666-17675. [PMID: 29932186 DOI: 10.1039/c8cp01415a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Glutathione (GSH), whose thiol group dictates its redox chemistry, is oxidized to the thiyl radical (GS˙), which rapidly dimerizes to GSSG. Previously, we found that the oxidation rate of GSH by IrCl62- depends on the base (B) concentration and the pKa of its conjugate acid BH+, so that collateral to a stepwise mechanism, the concerted pathway GSH + IrCl62- + B = GS˙ + IrCl63- + BH+ was proposed as the rate determining step. Herein, this investigation is extended to include oxidant-base pairs that render exothermic and endothermic conditions of ΔG°' for electron transfer (ET) and proton transfer (PT). Experiments were conducted by the reaction of GSH with an electrogenerated oxidant M+ and using digital simulations to infer the mechanism. Data analysis shows that despite parallel mechanisms, the concerted one seems to predominate for the oxidant-base pair that renders the most isoenergetic coupled state, whereby a PT with is capable of producing an ET with , as a result of the Nernstian shift of with pKa. In contrast, the stepwise PT-ET appears to dominate when GS- grows in stability as becomes more negative. Understanding the interplay between ET and PT will help in the design of catalysts for energy harvesting processes that rely on proton-coupled electron transfer.
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Affiliation(s)
- Kejie Meng
- Chemistry Department, Virginia Commonwealth University, Richmond, VA 23284, USA.
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162
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Chu KT, Liu YC, Chung MW, Poerwoprajitno AR, Lee GH, Chiang MH. Energy-Efficient Hydrogen Evolution by Fe-S Electrocatalysts: Mechanistic Investigations. Inorg Chem 2018; 57:7620-7630. [PMID: 29893554 DOI: 10.1021/acs.inorgchem.8b00543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The intrinsic catalytic property of a Fe-S complex toward H2 evolution was investigated in a wide range of acids. The title complex exhibited catalytic events at -1.16 and -1.57 V (vs Fc+/Fc) in the presence of trifluoromethanesulfonic acid (HOTf) and trifluoroacetic acid (TFA), respectively. The processes corresponded to the single reduction of the Fe-hydride-S-proton and Fe-hydride species, respectively. When anilinium acid was used, the catalysis occurred at -1.16 V, identical with the working potential of the HOTf catalysis, although the employment of anilinium acid was only capable of achieving the Fe-hydride state on the basis of the spectral and calculated results. The thermodynamics and kinetics of individual steps of the catalysis were analyzed by density functional theory (DFT) calculations and electroanalytical simulations. The stepwise CCE or CE (C, chemical; E, electrochemical) mechanism was operative from the HOTf or TFA source, respectively. In contrast, the involvement of anilinium acid most likely initiated a proton-coupled electron transfer (PCET) pathway that avoided the disfavored intermediate after the initial protonation. Via the PCET pathway, the heterogeneous electron transfer rate was increased and the overpotential was decreased by 0.4 V in comparison with the stepwise pathways. The results showed that the PCET-involved catalysis exhibited substantial kinetic and thermodynamic advantages in comparison to the stepwise pathway; thus, an efficient catalytic system for proton reduction was established.
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Affiliation(s)
- Kai-Ti Chu
- Institute of Chemistry , Academia Sinica , Nankang, Taipei 115 , Taiwan
| | - Yu-Chiao Liu
- Institute of Chemistry , Academia Sinica , Nankang, Taipei 115 , Taiwan
| | - Min-Wen Chung
- Institute of Chemistry , Academia Sinica , Nankang, Taipei 115 , Taiwan
| | | | - Gene-Hsiang Lee
- Instrumentation Center , National Taiwan University , Taipei 106 , Taiwan
| | - Ming-Hsi Chiang
- Institute of Chemistry , Academia Sinica , Nankang, Taipei 115 , Taiwan
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163
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The cytochrome b6f complex: DFT modeling of the first step of plastoquinol oxidation by the iron-sulfur protein. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2018.01.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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164
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Marzo L, Pagire SK, Reiser O, König B. Photokatalyse mit sichtbarem Licht: Welche Bedeutung hat sie für die organische Synthese? Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201709766] [Citation(s) in RCA: 306] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Leyre Marzo
- Institut für Organische Chemie; Universität Regensburg; Universitätsstraße 31 93053 Regensburg Deutschland
| | - Santosh K. Pagire
- Institut für Organische Chemie; Universität Regensburg; Universitätsstraße 31 93053 Regensburg Deutschland
| | - Oliver Reiser
- Institut für Organische Chemie; Universität Regensburg; Universitätsstraße 31 93053 Regensburg Deutschland
| | - Burkhard König
- Institut für Organische Chemie; Universität Regensburg; Universitätsstraße 31 93053 Regensburg Deutschland
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165
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Marzo L, Pagire SK, Reiser O, König B. Visible-Light Photocatalysis: Does It Make a Difference in Organic Synthesis? Angew Chem Int Ed Engl 2018; 57:10034-10072. [PMID: 29457971 DOI: 10.1002/anie.201709766] [Citation(s) in RCA: 1132] [Impact Index Per Article: 188.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 01/12/2018] [Indexed: 12/12/2022]
Abstract
Visible-light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross-coupling reactions, α-amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible-light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible-light-absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo- or metal catalysis.
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Affiliation(s)
- Leyre Marzo
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Santosh K Pagire
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Oliver Reiser
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Burkhard König
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
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166
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Khade RV, Dutta Choudhury S, Pal H, Kumbhar AS. Excited State Interaction of Ruthenium (II) Imidazole Phenanthroline Complex [Ru(bpy) 2 ipH] 2+ with 1,4-Benzoquinone: Simple Electron Transfer or Proton-Coupled Electron Transfer? Chemphyschem 2018; 19:2380-2388. [PMID: 29873437 DOI: 10.1002/cphc.201800313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Indexed: 11/07/2022]
Abstract
The unidirectional proton coupled electron transfer (PCET) from the excited state of Ru(II) imidazole phenanthroline complex [Ru(bpy)2 ipH]2+ to 1,4-benzoquinone, was studied by steady-state (SS) and time-resolved (TR) fluorescence and transient absorption (TA) measurements. The pKa (9.7) and pKa * (8.6) values of the complex suggest that it behaves as a photoacid on excitation. The difference in the quenching rates obtained from SS and TR fluorescence studies indicate participation of both dynamic quenching and static quenching involving the hydrogen bonded ipH ligand of [Ru(bpy)2 ipH]2+ with the 1,4-benzoquinone quencher, formed in the ground state. Within the hydrogen bonded complex, the ruthenium centre acts as the electron donor, while the ipH ligand acts as the proton donor to the hydrogen bonded 1,4-benzoquinone that acts simultaneously both as the electron and proton acceptor. It is proposed that the static quenching in the hydrogen bonded [Ru(bpy)2 ipH]2+ -1,4-benzoquinone pairs occurs involving the PCET mechanism, while the dynamic quenching occurs through the simple ET mechanism, on diffusional encounter of the isolated 1,4-benzoquinone with the excited [Ru(bpy)2 ipH]2+ complex. The occurrence of broad TA bands around 420-430 nm suggests formation of both 1,4-benzoquinone radical anion as well as the 1,4-benzosemiquinone radical by the interaction of excited [Ru(bpy)2 ipH]2+ with 1,4-benzoquinone, thus supporting the ET process in the studied system.
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Affiliation(s)
- Rahul V Khade
- Department of Chemistry, Savitribai Phule Pune University, Pune, 411007, India
| | | | - Haridas Pal
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Avinash S Kumbhar
- Department of Chemistry, Savitribai Phule Pune University, Pune, 411007, India
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167
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Yang JD, Ji P, Xue XS, Cheng JP. Recent Advances and Advisable Applications of Bond Energetics in Organic Chemistry. J Am Chem Soc 2018; 140:8611-8623. [DOI: 10.1021/jacs.8b04104] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jin-Dong Yang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Pengju Ji
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xiao-Song Xue
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Centre of Chemical Science and Engineering, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Jin-Pei Cheng
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Centre of Chemical Science and Engineering, College of Chemistry, Nankai University, Tianjin 300071, China
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168
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Reguera G. Harnessing the power of microbial nanowires. Microb Biotechnol 2018; 11:979-994. [PMID: 29806247 PMCID: PMC6201914 DOI: 10.1111/1751-7915.13280] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/13/2018] [Accepted: 04/22/2018] [Indexed: 12/13/2022] Open
Abstract
The reduction of iron oxide minerals and uranium in model metal reducers in the genus Geobacter is mediated by conductive pili composed primarily of a structurally divergent pilin peptide that is otherwise recognized, processed and assembled in the inner membrane by a conserved Type IVa pilus apparatus. Electronic coupling among the peptides is promoted upon assembly, allowing the discharge of respiratory electrons at rates that greatly exceed the rates of cellular respiration. Harnessing the unique properties of these conductive appendages and their peptide building blocks in metal bioremediation will require understanding of how the pilins assemble to form a protein nanowire with specialized sites for metal immobilization. Also important are insights into how cells assemble the pili to make an electroactive matrix and grow on electrodes as biofilms that harvest electrical currents from the oxidation of waste organic substrates. Genetic engineering shows promise to modulate the properties of the peptide building blocks, protein nanowires and current‐harvesting biofilms for various applications. This minireview discusses what is known about the pilus material properties and reactions they catalyse and how this information can be harnessed in nanotechnology, bioremediation and bioenergy applications.
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Affiliation(s)
- Gemma Reguera
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Rd., Rm. 6190, East Lansing, MI, 48824, USA
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169
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An antibacterial platform based on capacitive carbon-doped TiO 2 nanotubes after direct or alternating current charging. Nat Commun 2018; 9:2055. [PMID: 29795383 PMCID: PMC5967314 DOI: 10.1038/s41467-018-04317-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 04/20/2018] [Indexed: 01/12/2023] Open
Abstract
Electrical interactions between bacteria and the environment are delicate and essential. In this study, an external electrical current is applied to capacitive titania nanotubes doped with carbon (TNT-C) to evaluate the effects on bacteria killing and the underlying mechanism is investigated. When TNT-C is charged, post-charging antibacterial effects proportional to the capacitance are observed. This capacitance-based antibacterial system works well with both direct and alternating current (DC, AC) and the higher discharging capacity in the positive DC (DC+) group leads to better antibacterial performance. Extracellular electron transfer observed during early contact contributes to the surface-dependent post-charging antibacterial process. Physiologically, the electrical interaction deforms the bacteria morphology and elevates the intracellular reactive oxygen species level without impairing the growth of osteoblasts. Our finding spurs the design of light-independent antibacterial materials and provides insights into the use of electricity to modify biomaterials to complement other bacteria killing measures such as light irradiation. Bacteria are known to be sensitive to electrical interactions with the environment. Here, the authors report on a study into how the antibacterial properties of carbon-doped titania nanotubes are affected by capacitance after charging with direct and alternating currents.
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170
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Cioncoloni G, Roger I, Wheatley PS, Wilson C, Morris RE, Sproules S, Symes MD. Proton-Coupled Electron Transfer Enhances the Electrocatalytic Reduction of Nitrite to NO in a Bioinspired Copper Complex. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00361] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Giacomo Cioncoloni
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Isolda Roger
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Paul S. Wheatley
- EaStCHEM School of Chemistry, University of St Andrews, Purdie Building, St Andrews KY16 9ST, United Kingdom
| | - Claire Wilson
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Russell E. Morris
- EaStCHEM School of Chemistry, University of St Andrews, Purdie Building, St Andrews KY16 9ST, United Kingdom
| | - Stephen Sproules
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Mark D. Symes
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
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171
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Church MS, Hele TJH, Ezra GS, Ananth N. Nonadiabatic semiclassical dynamics in the mixed quantum-classical initial value representation. J Chem Phys 2018; 148:102326. [DOI: 10.1063/1.5005557] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Matthew S. Church
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Timothy J. H. Hele
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Gregory S. Ezra
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Nandini Ananth
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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172
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Kieffer IA, Allen RJ, Fernandez JL, Deobald JL, Thompson BL, Wimpenny JD, Heiden ZM. Utilization of a Fluorescent Dye Molecule as a Proton and Electron Reservoir. Angew Chem Int Ed Engl 2018; 57:3377-3380. [PMID: 29479783 DOI: 10.1002/anie.201713174] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Indexed: 11/08/2022]
Abstract
Fluorescent dyes have been widely utilized as chemical sensors and in photodynamic therapy, but exploitation of their redox-active nature in chemical reactions has remained mostly unexplored. This report describes the isolation of a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based radical. The redox-active nature of the BODIPY compound can be utilized in combination with a guanidine center, the basicity of which can be manipulated by greater than 14 pKa units, to promote the conversion of protons and electrons into H-atoms for transfer to substrate molecules.
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Affiliation(s)
- Ian A Kieffer
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
| | - Robert J Allen
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
| | - Jordan L Fernandez
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
| | - Jackson L Deobald
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
| | - Brena L Thompson
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
| | - Jacob D Wimpenny
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
| | - Zachariah M Heiden
- Department of Chemistry, Washington State University, P.O. Box 644630, Pullman, WA, 99164-4630, USA
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173
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Senger M, Mebs S, Duan J, Shulenina O, Laun K, Kertess L, Wittkamp F, Apfel UP, Happe T, Winkler M, Haumann M, Stripp ST. Protonation/reduction dynamics at the [4Fe-4S] cluster of the hydrogen-forming cofactor in [FeFe]-hydrogenases. Phys Chem Chem Phys 2018; 20:3128-3140. [PMID: 28884175 DOI: 10.1039/c7cp04757f] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The [FeFe]-hydrogenases of bacteria and algae are the most efficient hydrogen conversion catalysts in nature. Their active-site cofactor (H-cluster) comprises a [4Fe-4S] cluster linked to a unique diiron site that binds three carbon monoxide (CO) and two cyanide (CN-) ligands. Understanding microbial hydrogen conversion requires elucidation of the interplay of proton and electron transfer events at the H-cluster. We performed real-time spectroscopy on [FeFe]-hydrogenase protein films under controlled variation of atmospheric gas composition, sample pH, and reductant concentration. Attenuated total reflection Fourier-transform infrared spectroscopy was used to monitor shifts of the CO/CN- vibrational bands in response to redox and protonation changes. Three different [FeFe]-hydrogenases and several protein and cofactor variants were compared, including element and isotopic exchange studies. A protonated equivalent (HoxH) of the oxidized state (Hox) was found, which preferentially accumulated at acidic pH and under reducing conditions. We show that the one-electron reduced state Hred' represents an intrinsically protonated species. Interestingly, the formation of HoxH and Hred' was independent of the established proton pathway to the diiron site. Quantum chemical calculations of the respective CO/CN- infrared band patterns favored a cysteine ligand of the [4Fe-4S] cluster as the protonation site in HoxH and Hred'. We propose that proton-coupled electron transfer facilitates reduction of the [4Fe-4S] cluster and prevents premature formation of a hydride at the catalytic diiron site. Our findings imply that protonation events both at the [4Fe-4S] cluster and at the diiron site of the H-cluster are important in the hydrogen conversion reaction of [FeFe]-hydrogenases.
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Affiliation(s)
- Moritz Senger
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
| | - Stefan Mebs
- Department of Physics, Biophysics of Metalloenzymes, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Jifu Duan
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Olga Shulenina
- Faculty of Physics, St. Petersburg State University, 198504 St. Petersburg, Russian Federation
| | - Konstantin Laun
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
| | - Leonie Kertess
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Florian Wittkamp
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry I, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Ulf-Peter Apfel
- Faculty of Chemistry and Biochemistry, Inorganic Chemistry I, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Thomas Happe
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Martin Winkler
- Faculty of Biology and Biotechnology, Photobiotechnology, Ruhr-Universität Bochum, 44801 Bochum, Germany.
| | - Michael Haumann
- Department of Physics, Biophysics of Metalloenzymes, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
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174
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Kieffer IA, Allen RJ, Fernandez JL, Deobald JL, Thompson BL, Wimpenny JD, Heiden ZM. Utilization of a Fluorescent Dye Molecule as a Proton and Electron Reservoir. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201713174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Ian A. Kieffer
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
| | - Robert J. Allen
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
| | - Jordan L. Fernandez
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
| | - Jackson L. Deobald
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
| | - Brena L. Thompson
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
| | - Jacob D. Wimpenny
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
| | - Zachariah M. Heiden
- Department of Chemistry; Washington State University; P.O. Box 644630 Pullman WA 99164-4630 USA
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175
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Magerl K, Stambolic I, Dick B. Switching from adduct formation to electron transfer in a light-oxygen-voltage domain containing the reactive cysteine. Phys Chem Chem Phys 2018; 19:10808-10819. [PMID: 28271102 DOI: 10.1039/c6cp08370f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
LOV (light-, oxygen- or voltage-sensitive) domains act as photosensory units of many prokaryotic and eukaryotic proteins. Upon blue light excitation they undergo a photocycle via the excited triplet state of their flavin chromophore yielding the flavin-cysteinyl adduct. Adduct formation is highly conserved among all LOV domains and constitutes the primary step of LOV domain signaling. But recently, it has been shown that signal propagation can also be triggered by flavin photoreduction to the neutral semiquinone offering new prospects for protein engineering. This, however, requires mutation of the photo-active Cys. Here, we report on LOV1 mutants of C. reinhardtii phototropin in which adduct formation is suppressed although the photo-active Cys is present. Introduction of a Tyr into the LOV core induces a proton coupled electron transfer towards the flavin chromophore. Flavin radical species are formed via either the excited flavin singlet or triplet state depending on the geometry of donor and acceptor. This photoreductive pathway resembles the photoreaction observed in other blue light photoreceptors, e.g. blue-light sensors using flavin adenine dinucleotide (BLUF) domains or cryptochromes. The ability to tune the photoreactivity of the flavin chromophore inside the LOV core has implications for the mechanism of adduct formation in the wild type and may be of use for protein engineering.
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Affiliation(s)
- Kathrin Magerl
- Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitaetsstrasse 31, 93053 Regensburg, Germany.
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176
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Bezdek MJ, Chirik PJ. Interconversion of Molybdenum Imido and Amido Complexes by Proton-Coupled Electron Transfer. Angew Chem Int Ed Engl 2018; 57:2224-2228. [PMID: 29319929 DOI: 10.1002/anie.201708406] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/16/2017] [Indexed: 11/07/2022]
Abstract
Interconversion of the molybdenum amido [(Ph Tpy)(PPh2 Me)2 Mo(NHtBuAr)][BArF24 ] (Ph Tpy=4'-Ph-2,2',6',2"-terpyridine; tBuAr=4-tert-butyl-C6 H4 ; ArF24 =(C6 H3 -3,5-(CF3 )2 )4 ) and imido [(Ph Tpy)(PPh2 Me)2 Mo(NtBuAr)][BArF24 ] complexes has been accomplished by proton-coupled electron transfer. The 2,4,6-tri-tert-butylphenoxyl radical was used as an oxidant and the non-classical ammine complex [(Ph Tpy)(PPh2 Me)2 Mo(NH3 )][BArF24 ] as the reductant. The N-H bond dissociation free energy (BDFE) of the amido N-H bond formed and cleaved in the sequence was experimentally bracketed between 45.8 and 52.3 kcal mol-1 , in agreement with a DFT-computed value of 48 kcal mol-1 . The N-H BDFE in combination with electrochemical data eliminate proton transfer as the first step in the N-H bond-forming sequence and favor initial electron transfer or concerted pathways.
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Affiliation(s)
- Máté J Bezdek
- Department of Chemistry, Princeton University, Frick Laboratory 292, Princeton, 08544, USA
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Frick Laboratory 292, Princeton, 08544, USA
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177
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Bezdek MJ, Chirik PJ. Interconversion of Molybdenum Imido and Amido Complexes by Proton‐Coupled Electron Transfer. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201708406] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Máté J. Bezdek
- Department of Chemistry Princeton University Frick Laboratory 292 Princeton 08544 USA
| | - Paul J. Chirik
- Department of Chemistry Princeton University Frick Laboratory 292 Princeton 08544 USA
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178
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Greene BL, Taguchi AT, Stubbe J, Nocera DG. Conformationally Dynamic Radical Transfer within Ribonucleotide Reductase. J Am Chem Soc 2017; 139:16657-16665. [PMID: 29037038 DOI: 10.1021/jacs.7b08192] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ribonucleotide reductases (RNR) catalyze the reduction of nucleotides to deoxynucleotides through a mechanism involving an essential cysteine based thiyl radical. In the E. coli class 1a RNR the thiyl radical (C439•) is a transient species generated by radical transfer (RT) from a stable diferric-tyrosyl radical cofactor located >35 Å away across the α2:β2 subunit interface. RT is facilitated by sequential proton-coupled electron transfer (PCET) steps along a pathway of redox active amino acids (Y122β ↔ [W48β?] ↔ Y356β ↔ Y731α ↔ Y730α ↔ C439α). The mutant R411A(α) disrupts the H-bonding environment and conformation of Y731, ostensibly breaking the RT pathway in α2. However, the R411A protein retains significant enzymatic activity, suggesting Y731 is conformationally dynamic on the time scale of turnover. Installation of the radical trap 3-amino tyrosine (NH2Y) by amber codon suppression at positions Y731 or Y730 and investigation of the NH2Y• trapped state in the active α2:β2 complex by HYSCORE spectroscopy validate that the perturbed conformation of Y731 in R411A-α2 is dynamic, reforming the H-bond between Y731 and Y730 to allow RT to propagate to Y730. Kinetic studies facilitated by photochemical radical generation reveal that Y731 changes conformation on the ns-μs time scale, significantly faster than the enzymatic kcat. Furthermore, the kinetics of RT across the subunit interface were directly assessed for the first time, demonstrating conformationally dependent RT rates that increase from 0.6 to 1.6 × 104 s-1 when comparing wild type to R411A-α2, respectively. These results illustrate the role of conformational flexibility in modulating RT kinetics by targeting the PCET pathway of radical transport.
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Affiliation(s)
- Brandon L Greene
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Alexander T Taguchi
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - JoAnne Stubbe
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Daniel G Nocera
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
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179
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Wang Q, Zhao HY, Lo PK, Lam WWY, Lau KC, Lau TC. Proton-Coupled O-Atom Transfer in the Oxidation of HSO3– by the Ruthenium Oxo Complex trans-[RuVI(TMC)(O)2]2+ (TMC = 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane). Inorg Chem 2017; 56:12699-12702. [DOI: 10.1021/acs.inorgchem.7b02509] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Qian Wang
- School of Chemical
Engineering, Shandong University of Technology, Zibo 255049, P. R. China
- Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Hong Yan Zhao
- Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Po-Kam Lo
- Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - William W. Y. Lam
- Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China
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180
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Wang L, Fried SD, Markland TE. Proton Network Flexibility Enables Robustness and Large Electric Fields in the Ketosteroid Isomerase Active Site. J Phys Chem B 2017; 121:9807-9815. [DOI: 10.1021/acs.jpcb.7b06985] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Lu Wang
- Department
of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, United States
| | - Stephen D. Fried
- Medical Research
Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, U.K
| | - Thomas E. Markland
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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181
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Pannwitz A, Wenger OS. Photoinduced Electron Transfer Coupled to Donor Deprotonation and Acceptor Protonation in a Molecular Triad Mimicking Photosystem II. J Am Chem Soc 2017; 139:13308-13311. [PMID: 28906113 DOI: 10.1021/jacs.7b08761] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The first artificial donor-sensitizer-acceptor compound in which photoinduced long-range electron transfer is coupled to donor deprotonation and acceptor protonation is reported. The long-lived photoproduct stores energy in the form of a radical pair state in which the charges of the donor and the acceptor remain unchanged, much in contrast to previously investigated systems that exhibit charge-separated states comprised of electron-hole pairs. This finding is relevant for light-driven accumulation of redox equivalents, because it exemplifies how the buildup of charge can be avoided yet light energy can be stored. Proton-coupled electron transfer (PCET) reactions at a phenol donor and a monoquat acceptor triggered by excitation of a Ru(II) sensitizer enable this form of photochemical energy storage. Our triad emulates photosystem II more closely than previously investigated systems, because tyrosine Z is oxidized and deprotonated, whereas plastoquinone B is reduced and protonated.
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Affiliation(s)
- Andrea Pannwitz
- Department of Chemistry, University of Basel , St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel , St. Johanns-Ring 19, 4056 Basel, Switzerland
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182
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Zhang H, Wu W, Mo Y. Study of proton-coupled electron transfer (PCET) with four explicit diabatic states at the ab initio level. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2017.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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183
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Li J, Wang J, Wang D, Guo G, Yeung KWK, Zhang X, Liu X. Band Gap Engineering of Titania Film through Cobalt Regulation for Oxidative Damage of Bacterial Respiration and Viability. ACS APPLIED MATERIALS & INTERFACES 2017; 9:27475-27490. [PMID: 28748698 DOI: 10.1021/acsami.7b06867] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Biomaterial-related bacterial infections cause patient suffering, mortality, and extended periods of hospitalization and impose a substantial burden on medical systems. In this context, understanding the interactions between nanomaterials and bacteria is clinically significant. Herein, TiO2-based heterojunctions, including Co-TiO2, CoO-TiO2, and Co3O4-TiO2, were first designed by optimizing magnetron sputtering to establish a platform to explore the interactions between nanomaterials and bacteria. We found that the energy band bending and band gap narrowing were effectively promoted at the contact interface of the heterojunctions, which have the ability to induce abiotic reactive oxygen species formation. Using methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, in vitro studies showed that the heterojunctions of Co-TiO2, CoO-TiO2, and especially Co3O4-TiO2 can effectively downregulate the expression levels of bacterial respiratory genes and cause oxidative damage to bacterial membrane respiration and viability. As a result, the surfaces of the heterojunctions possess a favorable antiadherent bacterial activity. Moreover, using an osteomyelitis model, the preclinical study on rats further confirmed the favorable anti-infection effect of the elaborately designed heterojunctions (especially Co3O4-TiO2). We hope this study can provide new insights into the surface antibacterial design of biomaterials using energy band engineering for both basic research and clinical needs. Meanwhile, this attempt may also contribute to expanding the biomedical applications of cobalt-based nanoparticles for the treatment of antibiotic-resistant infections.
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Affiliation(s)
- Jinhua Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong , Pokfulam, Hong Kong 999077, China
- Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong-Shenzhen Hospital , Shenzhen 518053, China
- University of Chinese Academy of Sciences , Beijing 100049, China
| | - Jiaxing Wang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University , Shanghai 200233, China
| | - Donghui Wang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University , Shanghai 200233, China
| | - Geyong Guo
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University , Shanghai 200233, China
| | - Kelvin W K Yeung
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong , Pokfulam, Hong Kong 999077, China
- Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong-Shenzhen Hospital , Shenzhen 518053, China
| | - Xianlong Zhang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University , Shanghai 200233, China
| | - Xuanyong Liu
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , Shanghai 200050, China
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184
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Nick TU, Ravichandran KR, Stubbe J, Kasanmascheff M, Bennati M. Spectroscopic Evidence for a H Bond Network at Y 356 Located at the Subunit Interface of Active E. coli Ribonucleotide Reductase. Biochemistry 2017. [PMID: 28640584 DOI: 10.1021/acs.biochem.7b00462] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction catalyzed by E. coli ribonucleotide reductase (RNR) composed of α and β subunits that form an active α2β2 complex is a paradigm for proton-coupled electron transfer (PCET) processes in biological transformations. β2 contains the diferric tyrosyl radical (Y122·) cofactor that initiates radical transfer (RT) over 35 Å via a specific pathway of amino acids (Y122· ⇆ [W48] ⇆ Y356 in β2 to Y731 ⇆ Y730 ⇆ C439 in α2). Experimental evidence exists for colinear and orthogonal PCET in α2 and β2, respectively. No mechanistic model yet exists for the PCET across the subunit (α/β) interface. Here, we report unique EPR spectroscopic features of Y356·-β, the pathway intermediate generated by the reaction of 2,3,5-F3Y122·-β2/CDP/ATP with wt-α2, Y731F-α2, or Y730F-α2. High field EPR (94 and 263 GHz) reveals a dramatically perturbed g tensor. [1H] and [2H]-ENDOR reveal two exchangeable H bonds to Y356·: a moderate one almost in-plane with the π-system and a weak one. DFT calculation on small models of Y· indicates that two in-plane, moderate H bonds (rO-H ∼1.8-1.9 Å) are required to reproduce the gx value of Y356· (wt-α2). The results are consistent with a model, in which a cluster of two, almost symmetrically oriented, water molecules provide the two moderate H bonds to Y356· that likely form a hydrogen bond network of water molecules involved in either the reversible PCET across the subunit interface or in H+ release to the solvent during Y356 oxidation.
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Affiliation(s)
- Thomas U Nick
- Research Group Electron-Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany
| | - Kanchana R Ravichandran
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - JoAnne Stubbe
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Müge Kasanmascheff
- Research Group Electron-Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany
| | - Marina Bennati
- Research Group Electron-Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany.,Department of Chemistry, University of Göttingen , 37077 Göttingen, Germany
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185
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Hordiyenko OV, Biitseva AV, Kostina YY, Zubatyuk RI, Shishkin OV, Groth UM, Kornilov MY. The unsubstituted ortho-amidino benzoic acid: crystal structure, characterization and pK a determination. Struct Chem 2017. [DOI: 10.1007/s11224-016-0822-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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186
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Song K, Shi Q. Theoretical study of photoinduced proton coupled electron transfer reaction using the non-perturbative hierarchical equations of motion method. J Chem Phys 2017. [DOI: 10.1063/1.4982928] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Kai Song
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Shi
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China and University of Chinese Academy of Sciences, Beijing 100049, China
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187
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Long-range proton-coupled electron transfer in the Escherichia coli class Ia ribonucleotide reductase. Essays Biochem 2017; 61:281-292. [PMID: 28487404 DOI: 10.1042/ebc20160072] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 03/31/2017] [Accepted: 04/03/2017] [Indexed: 11/17/2022]
Abstract
Escherichia coli class Ia ribonucleotide reductase (RNR) catalyzes the conversion of nucleotides to 2'-deoxynucleotides using a radical mechanism. Each turnover requires radical transfer from an assembled diferric tyrosyl radical (Y•) cofactor to the enzyme active site over 35 Å away. This unprecedented reaction occurs via an amino acid radical hopping pathway spanning two protein subunits. To study the mechanism of radical transport in RNR, a suite of biochemical approaches have been developed, such as site-directed incorporation of unnatural amino acids with altered electronic properties and photochemical generation of radical intermediates. The resulting variant RNRs have been investigated using a variety of time-resolved physical techniques, including transient absorption and stopped-flow UV-Vis spectroscopy, as well as rapid freeze-quench EPR, ENDOR, and PELDOR spectroscopic methods. The data suggest that radical transport occurs via proton-coupled electron transfer (PCET) and that the protein structure has evolved to manage the proton and electron transfer co-ordinates in order to prevent 'off-pathway' reactivity and build-up of oxidised intermediates. Thus, precise design and control over the factors that govern PCET is key to enabling reversible and long-range charge transport by amino acid radicals in RNR.
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188
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Li J, Guo G, Wang J, Zhou H, Shen H, Yeung KWK. Anti-biofouling function of amorphous nano-Ta 2O 5 coating for VO 2-based intelligent windows. NANOTECHNOLOGY 2017; 28:175705. [PMID: 28367838 DOI: 10.1088/1361-6528/aa6525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
From environmental and health perspectives, the acquisition of a surface anti-biofouling property holds important significance for the usability of VO2 intelligent windows. Herein, we firstly deposited amorphous Ta2O5 nanoparticles on VO2 film by the magnetron sputtering method. It was found that the amorphous nano-Ta2O5 coating possessed a favorable anti-biofouling capability against Pseudomonas aeruginosa as an environmental microorganism model, behind which lay the mechanism that the amorphous nano-Ta2O5 could interrupt the microbial membrane electron transport chain and significantly elevate the intracellular reactive oxygen species (ROS) level. A plausible relationship was established between the anti-biofouling activity and physicochemical nature of amorphous Ta2O5 nanoparticles from the perspective of defect chemistry. ROS-induced oxidative damage gave rise to microbial viability loss. In addition, the amorphous nano-Ta2O5 coating can endow VO2 with favorable cytocompatibility with human skin fibroblasts. This study may provide new insights into understanding the anti-biofouling and antimicrobial actions of amorphous transition metal oxide nanoparticles, which is conducive to expanding their potential applications in environmental fields.
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Affiliation(s)
- Jinhua Li
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China. Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong Shenzhen Hospital, Shenzhen 518053, People's Republic of China. University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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189
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Wang J, Zhou H, Guo G, Cheng T, Peng X, Mao X, Li J, Zhang X. A functionalized surface modification with vanadium nanoparticles of various valences against implant-associated bloodstream infection. Int J Nanomedicine 2017; 12:3121-3136. [PMID: 28458535 PMCID: PMC5402895 DOI: 10.2147/ijn.s129459] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Bloodstream infection, especially with implants involved, is an often life-threatening condition with high mortality rates, imposing a heavy burden on patients and medical systems. Herein, we firstly deposited homogeneous vanadium metal, V2O3, VO2, and V2O5 nanofilms on quartz glass by magnetron sputtering. Using these platforms, we further investigated the potential antimicrobial efficiency of these nano-VOx films and the interactions of human erythrocytes and bacteria (methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa) with our samples in a novel cell–bacteria coculture model. It was demonstrated that these nano-VOx precipitated favorable antibacterial activity on both bacteria, especially on S. aureus, and this effect increased with higher vanadium valence. A possible mechanism accountable for these results might be elevated levels of vanadium-induced intracellular reactive oxygen species. More importantly, based on hemolysis assays, our nano-VOx films were found to be able to kill prokaryotic cells but were not toxic to mammalian cells, holding the potential for the prevention of implant-related hematogenous infections. As far as we know, this is the first report wherein such nano-VOx films have assisted human erythrocytes to combat bacteria in a valence-dependent manner. Additionally, vanadium ions were released from these nano-VOx films in a sustained manner, and low-valence films possessed better biocompatibility with human fibroblasts. This work may provide new insights for biomedical applications of inorganic vanadium compounds and attract growing attention in this field. From the perspective of surface modification and functionalization, this study holds promise to avail the prophylaxis of bloodstream infections involving implantable biomedical devices.
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Affiliation(s)
- Jiaxing Wang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University
| | - Huaijuan Zhou
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai
| | - Geyong Guo
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University
| | - Tao Cheng
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University
| | - Xiaochun Peng
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University
| | - Xin Mao
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University
| | - Jinhua Li
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai.,Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.,University of Chinese Academy of Sciences, Beijing, China
| | - Xianlong Zhang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University
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190
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Cattaneo M, Ryken SA, Mayer JM. Outer‐Sphere 2 e
−
/2 H
+
Transfer Reactions of Ruthenium(II)‐Amine and Ruthenium(IV)‐Amido Complexes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201612642] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Mauricio Cattaneo
- Department of Chemistry University of Washington USA
- INQUINOA-CONICET Universidad Nacional de Tucumán Ayacucho 471 (T4000INI) San Miguel de Tucumán Argentina
| | | | - James M. Mayer
- Department of Chemistry University of Washington USA
- Department of Chemistry Yale University P.O. Box 208107 New Haven CT 06520 USA
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191
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Ravichandran KR, Zong AB, Taguchi AT, Nocera DG, Stubbe J, Tommos C. Formal Reduction Potentials of Difluorotyrosine and Trifluorotyrosine Protein Residues: Defining the Thermodynamics of Multistep Radical Transfer. J Am Chem Soc 2017; 139:2994-3004. [PMID: 28171730 DOI: 10.1021/jacs.6b11011] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Redox-active tyrosines (Ys) play essential roles in enzymes involved in primary metabolism including energy transduction and deoxynucleotide production catalyzed by ribonucleotide reductases (RNRs). Thermodynamic characterization of Ys in solution and in proteins remains a challenge due to the high reduction potentials involved and the reactive nature of the radical state. The structurally characterized α3Y model protein has allowed the first determination of formal reduction potentials (E°') for a Y residing within a protein (Berry, B. W.; Martı́nez-Rivera, M. C.; Tommos, C. Proc. Natl. Acad. Sci. U. S. A. 2012, 109, 9739-9743). Using Schultz's technology, a series of fluorotyrosines (FnY, n = 2 or 3) was site-specifically incorporated into α3Y. The global protein properties of the resulting α3(3,5)F2Y, α3(2,3,5)F3Y, α3(2,3)F2Y and α3(2,3,6)F3Y variants are essentially identical to those of α3Y. A protein film square-wave voltammetry approach was developed to successfully obtain reversible voltammograms and E°'s of the very high-potential α3FnY proteins. E°'(pH 5.5; α3FnY(O•/OH)) spans a range of 1040 ± 3 mV to 1200 ± 3 mV versus the normal hydrogen electrode. This is comparable to the potentials of the most oxidizing redox cofactors in nature. The FnY analogues, and the ability to site-specifically incorporate them into any protein of interest, provide new tools for mechanistic studies on redox-active Ys in proteins and on functional and aberrant hole-transfer reactions in metallo-enzymes. The former application is illustrated here by using the determined α3FnY ΔE°'s to model the thermodynamics of radical-transfer reactions in FnY-RNRs and to experimentally test and support the key prediction made.
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Affiliation(s)
| | - Allan B Zong
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania 19104, United States
| | | | - Daniel G Nocera
- Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | | | - Cecilia Tommos
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania 19104, United States
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192
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Cattaneo M, Ryken SA, Mayer JM. Outer-Sphere 2 e - /2 H + Transfer Reactions of Ruthenium(II)-Amine and Ruthenium(IV)-Amido Complexes. Angew Chem Int Ed Engl 2017; 56:3675-3678. [PMID: 28206699 DOI: 10.1002/anie.201612642] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Indexed: 11/11/2022]
Abstract
A diverse set of 2 e- /2 H+ reactions are described that interconvert [RuII (bpy)(en*)2 ]2+ and [RuIV (bpy)(en-H*)2 ]2+ (bpy=2,2'-bipyridine, en*=H2 NCMe2 CMe2 NH2 , en*-H=H2 NCMe2 CMe2 NH- ), forming or cleaving different O-H, N-H, S-H, and C-H bonds. The reactions involve quinones, hydrazines, thiols, and 1,3-cyclohexadiene. These proton-coupled electron transfer reactions occur without substrate binding to the ruthenium center, but instead with precursor complex formation by hydrogen bonding. The free energies of the reactions vary over more than 90 kcal mol-1 , but the rates are more dependent on the type of X-H bond involved than the associated ΔG°. There is a kinetic preference for substrates that have the transferring hydrogen atoms in close proximity, such as ortho-tetrachlorobenzoquinone over its para-isomer and 1,3-cyclohexadiene over its 1,4-isomer, perhaps hinting at the potential for concerted 2 e- /2 H+ transfers.
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Affiliation(s)
- Mauricio Cattaneo
- Department of Chemistry, University of Washington, USA.,INQUINOA-CONICET, Universidad Nacional de Tucumán, Ayacucho 471 (T4000INI), San Miguel de Tucumán, Argentina
| | - Scott A Ryken
- Department of Chemistry, University of Washington, USA
| | - James M Mayer
- Department of Chemistry, University of Washington, USA.,Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT, 06520, USA
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193
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Glover SD, Parada GA, Markle TF, Ott S, Hammarström L. Isolating the Effects of the Proton Tunneling Distance on Proton-Coupled Electron Transfer in a Series of Homologous Tyrosine-Base Model Compounds. J Am Chem Soc 2017; 139:2090-2101. [DOI: 10.1021/jacs.6b12531] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Starla D. Glover
- Department of Chemistry−Ångström, Uppsala University, Box
532, SE-751 20, Uppsala, Sweden
| | - Giovanny A. Parada
- Department of Chemistry−Ångström, Uppsala University, Box
532, SE-751 20, Uppsala, Sweden
| | - Todd F. Markle
- Department of Chemistry−Ångström, Uppsala University, Box
532, SE-751 20, Uppsala, Sweden
| | - Sascha Ott
- Department of Chemistry−Ångström, Uppsala University, Box
532, SE-751 20, Uppsala, Sweden
| | - Leif Hammarström
- Department of Chemistry−Ångström, Uppsala University, Box
532, SE-751 20, Uppsala, Sweden
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194
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Sequential and Coupled Proton and Electron Transfer Events in the S2 → S3 Transition of Photosynthetic Water Oxidation Revealed by Time-Resolved X-ray Absorption Spectroscopy. Biochemistry 2016; 55:6996-7004. [DOI: 10.1021/acs.biochem.6b01078] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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195
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Catalytic alkylation of remote C-H bonds enabled by proton-coupled electron transfer. Nature 2016; 539:268-271. [PMID: 27732585 DOI: 10.1038/nature19811] [Citation(s) in RCA: 543] [Impact Index Per Article: 67.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Accepted: 08/25/2016] [Indexed: 12/22/2022]
Abstract
Despite advances in hydrogen atom transfer (HAT) catalysis, there are currently no molecular HAT catalysts that are capable of homolysing the strong nitrogen-hydrogen (N-H) bonds of N-alkyl amides. The motivation to develop amide homolysis protocols stems from the utility of the resultant amidyl radicals, which are involved in various synthetically useful transformations, including olefin amination and directed carbon-hydrogen (C-H) bond functionalization. In the latter process-a subset of the classical Hofmann-Löffler-Freytag reaction-amidyl radicals remove hydrogen atoms from unactivated aliphatic C-H bonds. Although powerful, these transformations typically require oxidative N-prefunctionalization of the amide starting materials to achieve efficient amidyl generation. Moreover, because these N-activating groups are often incorporated into the final products, these methods are generally not amenable to the direct construction of carbon-carbon (C-C) bonds. Here we report an approach that overcomes these limitations by homolysing the N-H bonds of N-alkyl amides via proton-coupled electron transfer. In this protocol, an excited-state iridium photocatalyst and a weak phosphate base cooperatively serve to remove both a proton and an electron from an amide substrate in a concerted elementary step. The resultant amidyl radical intermediates are shown to promote subsequent C-H abstraction and radical alkylation steps. This C-H alkylation represents a catalytic variant of the Hofmann-Löffler-Freytag reaction, using simple, unfunctionalized amides to direct the formation of new C-C bonds. Given the prevalence of amides in pharmaceuticals and natural products, we anticipate that this method will simplify the synthesis and structural elaboration of amine-containing targets. Moreover, this study demonstrates that concerted proton-coupled electron transfer can enable homolytic activation of common organic functional groups that are energetically inaccessible using traditional HAT-based approaches.
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196
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Li X, Markandeya N, Jonusauskas G, McClenaghan ND, Maurizot V, Denisov SA, Huc I. Photoinduced Electron Transfer and Hole Migration in Nanosized Helical Aromatic Oligoamide Foldamers. J Am Chem Soc 2016; 138:13568-13578. [DOI: 10.1021/jacs.6b05668] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Xuesong Li
- Univ. de Bordeaux, CBMN (UMR 5248), Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33600 Pessac, France
- CNRS, CBMN (UMR 5248), Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33600 Pessac, France
| | - Nagula Markandeya
- Univ. de Bordeaux, CBMN (UMR 5248), Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33600 Pessac, France
- CNRS, CBMN (UMR 5248), Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33600 Pessac, France
| | - Gediminas Jonusauskas
- Univ. de Bordeaux, Laboratoire Ondes et Matières
d’Aquitaine (UMR5798), 351 cours de la Libération, 33405 Talence cedex, France
| | - Nathan D. McClenaghan
- Univ. de Bordeaux, Institut des Sciences Moléculaires
(UMR5255), 351 cours de
la Libération, 33405 Talence cedex, France
| | - Victor Maurizot
- CNRS, CBMN (UMR 5248), Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33600 Pessac, France
| | - Sergey A. Denisov
- Univ. de Bordeaux, Institut des Sciences Moléculaires
(UMR5255), 351 cours de
la Libération, 33405 Talence cedex, France
| | - Ivan Huc
- CNRS, CBMN (UMR 5248), Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33600 Pessac, France
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197
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Verma S, Aute S, Das A, Ghosh HN. Proton-Coupled Electron Transfer in a Hydrogen-Bonded Charge-Transfer Complex. J Phys Chem B 2016; 120:10780-10785. [DOI: 10.1021/acs.jpcb.6b06032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sandeep Verma
- Radiation
and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Sunil Aute
- CSIR-National Chemical Laboratory, Pune 411008, India
| | - Amitava Das
- CSIR-National Chemical Laboratory, Pune 411008, India
- CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, India
| | - Hirendra N. Ghosh
- Radiation
and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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198
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Chen L, Zheng H, Li W, Li W, Miao Y, Feng C. Role of a Conserved Tyrosine Residue in the FMN-Heme Interdomain Electron Transfer in Inducible Nitric Oxide Synthase. J Phys Chem A 2016; 120:7610-7616. [PMID: 27633182 DOI: 10.1021/acs.jpca.6b08207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interdomain electron transfer (IET) between the flavin mononucleotide (FMN) and heme domains is essential in the biosynthesis of nitric oxide (NO) by the NO synthase (NOS) enzymes. A conserved tyrosine residue in the FMN domain (Y631 in human inducible NOS) was proposed to be a key part of the electron transfer pathway in the FMN/heme docked complex model. In the present study, the FMN-heme IET kinetics in the Y631F mutant and wild type of a bidomain oxygenase/FMN construct of human inducible NOS were determined by laser flash photolysis. The rate constant of the Y631F mutant is significantly decreased by ∼75% (compared to the wild type), showing that the tyrosine residue indeed facilitates the FMN-heme IET through the protein medium. The IET rate constant of the wild type protein decreases from 345 to 242 s-1 on going from H2O to 95% D2O, giving a solvent kinetic isotope effect of 1.4. In contrast, no deuterium isotope effect was observed for the Tyr-to-Phe mutant. Moreover, an appreciable change in the wild type iNOS IET rate constant value was observed upon changing pH. These results indicate that the FMN-heme IET is proton coupled, in which the conserved tyrosine residue may play an important role.
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Affiliation(s)
- Li Chen
- College of Pharmacy, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Huayu Zheng
- College of Pharmacy, University of New Mexico , Albuquerque, New Mexico 87131, United States.,Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Wenbing Li
- College of Pharmacy, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Wei Li
- College of Pharmacy, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Yubin Miao
- Radiology, University of Colorado Denver , Denver, Colorado 80045, United States
| | - Changjian Feng
- College of Pharmacy, University of New Mexico , Albuquerque, New Mexico 87131, United States.,Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States
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199
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Wang G, Feng H, Gao A, Hao Q, Jin W, Peng X, Li W, Wu G, Chu PK. Extracellular Electron Transfer from Aerobic Bacteria to Au-Loaded TiO2 Semiconductor without Light: A New Bacteria-Killing Mechanism Other than Localized Surface Plasmon Resonance or Microbial Fuel Cells. ACS APPLIED MATERIALS & INTERFACES 2016; 8:24509-16. [PMID: 27580379 DOI: 10.1021/acsami.6b10052] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Titania loaded with noble metal nanoparticles exhibits enhanced photocatalytic killing of bacteria under light illumination due to the localized surface plasmon resonance (LSPR) property. It has been shown recently that loading with Au or Ag can also endow TiO2 with the antibacterial ability in the absence of light. In this work, the antibacterial mechanism of Au-loaded TiO2 nanotubes (Au@TiO2-NT) in the dark environment is studied, and a novel type of extracellular electron transfer (EET) between the bacteria and the surface of the materials is observed to cause bacteria death. Although the EET-induced bacteria current is similar to the LSPR-related photocurrent, the former takes place without light, and no reactive oxygen species (ROS) are produced during the process. The EET is also different from that commonly attributed to microbial fuel cells (MFC) because it is dominated mainly by the materials' surface, but not the bacteria, and the environment is aerobic. EET on the Au@TiO2-NT surface kills Staphylococcus aureus, but if it is combined with special MFC bacteria, the efficiency of MFC may be improved significantly.
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Affiliation(s)
- Guomin Wang
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Hongqing Feng
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, National Center for Nanoscience and Technology (NCNST) , Beijing 100083, P. R. China
| | - Ang Gao
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Qi Hao
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Weihong Jin
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Xiang Peng
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Wan Li
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Guosong Wu
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Paul K Chu
- Department of Physics and Materials Science, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, China
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200
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Luo J, Zhang J. Aerobic Oxidation of Olefins and Lignin Model Compounds Using Photogenerated Phthalimide-N-oxyl Radical. J Org Chem 2016; 81:9131-9137. [DOI: 10.1021/acs.joc.6b01704] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Jian Luo
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | - Jian Zhang
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
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