1
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Birch-Price Z, Hardy FJ, Lister TM, Kohn AR, Green AP. Noncanonical Amino Acids in Biocatalysis. Chem Rev 2024; 124:8740-8786. [PMID: 38959423 PMCID: PMC11273360 DOI: 10.1021/acs.chemrev.4c00120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 06/11/2024] [Accepted: 06/12/2024] [Indexed: 07/05/2024]
Abstract
In recent years, powerful genetic code reprogramming methods have emerged that allow new functional components to be embedded into proteins as noncanonical amino acid (ncAA) side chains. In this review, we will illustrate how the availability of an expanded set of amino acid building blocks has opened a wealth of new opportunities in enzymology and biocatalysis research. Genetic code reprogramming has provided new insights into enzyme mechanisms by allowing introduction of new spectroscopic probes and the targeted replacement of individual atoms or functional groups. NcAAs have also been used to develop engineered biocatalysts with improved activity, selectivity, and stability, as well as enzymes with artificial regulatory elements that are responsive to external stimuli. Perhaps most ambitiously, the combination of genetic code reprogramming and laboratory evolution has given rise to new classes of enzymes that use ncAAs as key catalytic elements. With the framework for developing ncAA-containing biocatalysts now firmly established, we are optimistic that genetic code reprogramming will become a progressively more powerful tool in the armory of enzyme designers and engineers in the coming years.
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Affiliation(s)
| | | | | | | | - Anthony P. Green
- Manchester Institute of Biotechnology,
School of Chemistry, University of Manchester, Manchester M1 7DN, U.K.
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2
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Ansari M, Bhattacharjee S, Pantazis DA. Correlating Structure with Spectroscopy in Ascorbate Peroxidase Compound II. J Am Chem Soc 2024; 146:9640-9656. [PMID: 38530124 PMCID: PMC11009960 DOI: 10.1021/jacs.3c13169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 03/15/2024] [Accepted: 03/15/2024] [Indexed: 03/27/2024]
Abstract
Structural and spectroscopic investigations of compound II in ascorbate peroxidase (APX) have yielded conflicting conclusions regarding the protonation state of the crucial Fe(IV) intermediate. Neutron diffraction and crystallographic data support an iron(IV)-hydroxo formulation, whereas Mössbauer, X-ray absorption (XAS), and nuclear resonance vibrational spectroscopy (NRVS) studies appear consistent with an iron(IV)-oxo species. Here we examine APX with spectroscopy-oriented QM/MM calculations and extensive exploration of the conformational space for both possible formulations of compound II. We establish that irrespective of variations in the orientation of a vicinal arginine residue and potential reorganization of proximal water molecules and hydrogen bonding, the Fe-O distances for the oxo and hydroxo forms consistently fall within distinct, narrow, and nonoverlapping ranges. The accuracy of geometric parameters is validated by coupled-cluster calculations with the domain-based local pair natural orbital approach, DLPNO-CCSD(T). QM/MM calculations of spectroscopic properties are conducted for all structural variants, encompassing Mössbauer, optical, X-ray absorption, and X-ray emission spectroscopies and NRVS. All spectroscopic observations can be assigned uniquely to an Fe(IV)═O form. A terminal hydroxy group cannot be reconciled with the spectroscopic data. Under no conditions can the Fe(IV)═O distance be sufficiently elongated to approach the crystallographically reported Fe-O distance. The latter is consistent only with a hydroxo species, either Fe(IV) or Fe(III). Our findings strongly support the Fe(IV)═O formulation of APX-II and highlight unresolved discrepancies in the nature of samples used across different experimental studies.
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Affiliation(s)
- Mursaleem Ansari
- Max-Planck-Institut für
Kohlenforschung, Kaiser-Wilhelm-Platz
1, Mülheim an der Ruhr 45470, Germany
| | - Sinjini Bhattacharjee
- Max-Planck-Institut für
Kohlenforschung, Kaiser-Wilhelm-Platz
1, Mülheim an der Ruhr 45470, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für
Kohlenforschung, Kaiser-Wilhelm-Platz
1, Mülheim an der Ruhr 45470, Germany
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3
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Guo W, Kang C, Wang X, Zhang H, Yuan L, Wei X, Xiao Q, Hao W. Chlorocholine chloride exposure induced spermatogenic dysfunction via iron overload caused by AhR/PERK axis-dependent ferritinophagy activation. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 274:116193. [PMID: 38460407 DOI: 10.1016/j.ecoenv.2024.116193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/28/2024] [Accepted: 03/06/2024] [Indexed: 03/11/2024]
Abstract
Chlorocholine chloride (CCC) is a plant growth regulator used worldwide that is detectable in cereals, fruits and animal products. The health effects of CCC exposure have raised public concern. Our previous research showed that CCC exposure decreased testosterone synthesis in pubertal rats. However, little is known about whether and how pubertal CCC exposure impacts spermatogenesis. In this study, we used BALB/c mice and spermatogonia-derived GC-1 cells to examine CCC-induced spermatogenic dysfunction. In vivo, pubertal CCC exposure led to decreased testicular weight, decreased testicular germ cells and poor sperm quality. This effect worsened after cessation of CCC exposure for the next 30 days. RNA-seq and western blot analysis revealed that CCC induced aryl hydrocarbon receptor (AhR) signaling, endoplasmic reticulum stress (ERS) and ferritinophagy. Increased iron content and lipid peroxidation levels were also observed in CCC-treated testes. In vitro, it was identified that iron overload mediated by enhanced ferritinophagy occurred in CCC-treated GC-1 cells, which might be attributed to the PERK pathway in ERS. Further, for the first time, our study elucidated the involvement of AhR in CCC-induced iron overload, which aggravated testicular oxidative damage via lipid peroxidation. Considering the adverse impact of CCC exposure on rodents, supportive evidence from GC-1 cells, and the critical importance of spermatogenesis on male development, the effects of CCC on the male reproduction warrant increased attention.
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Affiliation(s)
- Wanqian Guo
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Chenping Kang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Xiaoxia Wang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Haoran Zhang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Lilan Yuan
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Xuetao Wei
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Qianqian Xiao
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China.
| | - Weidong Hao
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China.
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4
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Follmer AH, Borovik AS. The role of basicity in selective C-H bond activation by transition metal-oxidos. Dalton Trans 2023; 52:11005-11016. [PMID: 37497779 PMCID: PMC10619463 DOI: 10.1039/d3dt01781h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The development of (bio)catalysts capable of selectively activating strong C-H bonds is a continuing challenge in modern chemistry. In both metalloenzymes and synthetic systems capable of activating C-H bonds, transition metal-oxido intermediates serve as the active species for reactivity whose thermodynamic properties influence the bond strengths they are capable of activating. In this Frontier article, we present current ideas of how the basicity of transition metal-oxidos impacts their reactivity with C-H bonds and present new opportunities within this field. We highlight recent insights into the role basicity plays in the activation process and its influence on mechanism, as well as the important role that secondary coordination sphere effects, such as hydrogen bonds, in tuning the basicity of the metal-oxido species is discussed.
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Affiliation(s)
- Alec H Follmer
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697-3900, USA.
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697-3900, USA.
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5
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Lučić M, Wilson MT, Tosha T, Sugimoto H, Shilova A, Axford D, Owen RL, Hough MA, Worrall JAR. Serial Femtosecond Crystallography Reveals the Role of Water in the One- or Two-Electron Redox Chemistry of Compound I in the Catalytic Cycle of the B-Type Dye-Decolorizing Peroxidase DtpB. ACS Catal 2022; 12:13349-13359. [PMID: 36366763 PMCID: PMC9638988 DOI: 10.1021/acscatal.2c03754] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/05/2022] [Indexed: 11/30/2022]
Abstract
![]()
Controlling the reactivity
of high-valent Fe(IV)–O
catalytic
intermediates, Compounds I and II, generated in heme enzymes upon
reaction with dioxygen or hydrogen peroxide, is important for function.
It has been hypothesized that the presence (wet) or absence (dry)
of distal heme pocket water molecules can influence whether Compound
I undergoes sequential one-electron additions or a concerted two-electron
reduction. To test this hypothesis, we investigate the role of water
in the heme distal pocket of a dye-decolorizing peroxidase utilizing
a combination of serial femtosecond crystallography and rapid kinetic
studies. In a dry distal heme site, Compound I reduction proceeds
through a mechanism in which Compound II concentration is low. This
reaction shows a strong deuterium isotope effect, indicating that
reduction is coupled to proton uptake. The resulting protonated Compound
II (Fe(IV)–OH) rapidly reduces to the ferric state, giving
the appearance of a two-electron transfer process. In a wet site,
reduction of Compound I is faster, has no deuterium effect, and yields
highly populated Compound II, which is subsequently reduced to the
ferric form. This work provides a definitive experimental test of
the hypothesis advanced in the literature that relates sequential
or concerted electron transfer to Compound I in wet or dry distal
heme sites.
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Affiliation(s)
- Marina Lučić
- School of Life Sciences, University of Essex, Wivenhoe Park,
Essex, ColchesterCO4 3SQ, U.K
| | - Michael T. Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park,
Essex, ColchesterCO4 3SQ, U.K
| | - Takehiko Tosha
- RIKEN, Spring-8 Center, 1-1-1 Kouto, Sayo, Hyogo679-5148Japan
| | | | - Anastasya Shilova
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, DidcotOX11 0DE, U.K
| | - Danny Axford
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, DidcotOX11 0DE, U.K
| | - Robin L. Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, DidcotOX11 0DE, U.K
| | - Michael A. Hough
- School of Life Sciences, University of Essex, Wivenhoe Park,
Essex, ColchesterCO4 3SQ, U.K
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, DidcotOX11 0DE, U.K
| | - Jonathan A. R. Worrall
- School of Life Sciences, University of Essex, Wivenhoe Park,
Essex, ColchesterCO4 3SQ, U.K
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6
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Guo C, Chadwick RJ, Foulis A, Bedendi G, Lubskyy A, Rodriguez KJ, Pellizzoni MM, Milton RD, Beveridge R, Bruns N. Peroxidase Activity of Myoglobin Variants Reconstituted with Artificial Cofactors. Chembiochem 2022; 23:e202200197. [PMID: 35816250 PMCID: PMC9545363 DOI: 10.1002/cbic.202200197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 07/08/2022] [Indexed: 02/02/2023]
Abstract
Myoglobin (Mb) can react with hydrogen peroxide (H2 O2 ) to form a highly active intermediate compound and catalyse oxidation reactions. To enhance this activity, known as pseudo-peroxidase activity, previous studies have focused on the modification of key amino acid residues of Mb or the heme cofactor. In this work, the Mb scaffold (apo-Mb) was systematically reconstituted with a set of cofactors based on six metal ions and two ligands. These Mb variants were fully characterised by UV-Vis spectroscopy, circular dichroism (CD) spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS) and native mass spectrometry (nMS). The steady-state kinetics of guaiacol oxidation and 2,4,6-trichlorophenol (TCP) dehalogenation catalysed by Mb variants were determined. Mb variants with iron chlorin e6 (Fe-Ce6) and manganese chlorin e6 (Mn-Ce6) cofactors were found to have improved catalytic efficiency for both guaiacol and TCP substrates in comparison with wild-type Mb, i. e. Fe-protoporphyrin IX-Mb. Furthermore, the selected cofactors were incorporated into the scaffold of a Mb mutant, swMb H64D. Enhanced peroxidase activity for both substrates were found via the reconstitution of Fe-Ce6 into the mutant scaffold.
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Affiliation(s)
- Chao Guo
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetG1 1XLGlasgowUK
| | - Robert J. Chadwick
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetG1 1XLGlasgowUK
| | - Adam Foulis
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetG1 1XLGlasgowUK
| | - Giada Bedendi
- Department of Inorganic and Analytical ChemistryUniversity of Geneva1211Geneva 4Switzerland
| | - Andriy Lubskyy
- Adolphe Merkle InstituteUniversity of FribourgChemin des Verdiers 41700FribourgSwitzerland
| | - Kyle J. Rodriguez
- Adolphe Merkle InstituteUniversity of FribourgChemin des Verdiers 41700FribourgSwitzerland
| | - Michela M. Pellizzoni
- Adolphe Merkle InstituteUniversity of FribourgChemin des Verdiers 41700FribourgSwitzerland
| | - Ross D. Milton
- Department of Inorganic and Analytical ChemistryUniversity of Geneva1211Geneva 4Switzerland
| | - Rebecca Beveridge
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetG1 1XLGlasgowUK
| | - Nico Bruns
- Department of Pure and Applied ChemistryUniversity of Strathclyde295 Cathedral StreetG1 1XLGlasgowUK,Department of ChemistryTechnical University of DarmstadtAlarich-Weiss-Str. 464287DarmstadtGermany
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7
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Hill K, Bailey BG, Mouton MB, Williamson HR. Hidden Complexity in the Mechanism of the Autoreduction of Myoglobin Compound II. ACS OMEGA 2022; 7:22906-22914. [PMID: 35811930 PMCID: PMC9260896 DOI: 10.1021/acsomega.2c02798] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
The non-native oxidation of horse heart myoglobin with hydrogen peroxide produces compound II which autoreduces by utilizing an internal oxidation site. Here, we utilize full UV-visible time-dependent kinetics with global kinetic singular value decomposition analysis to explore the mechanism and uncover more detail about the high-valent heme spectral features. By varying the hydrogen peroxide and myoglobin concentration, we were able to uncover more detailed spectra of myoglobin compound II and the autoreduction rate under several different pH conditions. The compound II spectra demonstrate pH-dependent features with an inflection point around pH 5.7 ± 0.1. The rate of autoreduction of compound II, k 2, increases with lower pH with a half-power proton dependence and no indication of a pK a > 3.9 ± 0.2, indicating that the autoreduction is still dependent on the protonation of the ferryl oxo species. The k 2 also demonstrates both hydrogen peroxide and myoglobin dependency. At myoglobin concentrations greater than 6.6 μM, the k 2 is myoglobin-independent, but for lower concentrations, a pH-sensitive concentration dependence is seen.
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Affiliation(s)
| | - Breanna G. Bailey
- Department of Chemistry, Xavier
University of Louisiana, 1 Drexel Dr., New Orleans, Louisiana 70125, United States
| | - Meghan B. Mouton
- Department of Chemistry, Xavier
University of Louisiana, 1 Drexel Dr., New Orleans, Louisiana 70125, United States
| | - Heather R. Williamson
- Department of Chemistry, Xavier
University of Louisiana, 1 Drexel Dr., New Orleans, Louisiana 70125, United States
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8
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Aboelnga MM. Mechanistic insights into the chemistry of compound I formation in heme peroxidases: quantum chemical investigations of cytochrome c peroxidase. RSC Adv 2022; 12:15543-15554. [PMID: 35685178 PMCID: PMC9125774 DOI: 10.1039/d2ra01073a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/17/2022] [Indexed: 11/21/2022] Open
Abstract
Peroxidases are heme containing enzymes that catalyze peroxide-dependant oxidation of a variety of substrates through forming key ferryl intermediates, compounds I and II. Cytochrome c peroxidase (Ccp1) has served for decades as a chemical model toward understanding the chemical biology of this heme family of enzymes. It is known to feature a distinctive electronic behaviour for its compound I despite significant structural similarity to other peroxidases. A water-assisted mechanism has been proposed over a dry one for the formation of compound I in similar peroxidases. To better identify the viability of these mechanisms, we employed quantum chemistry calculations for the heme pocket of Ccp1 in three different spin states. We provided comparative energetic and structural results for the six possible pathways that suggest the preference of the dry mechanism energetically and structurally. The doublet state is found to be the most preferable spin state for the mechanism to proceed and for the formation of the Cpd I ferryl-intermediate irrespective of the considered dielectric constant used to represent the solvent environment. The nature of the spin state has negligible effects on the calculated structures but great impact on the energetics. Our analysis was also expanded to explain the major contribution of key residues to the peroxidase activity of Ccp1 through exploring the mechanism at various in silico generated Ccp1 variants. Overall, we provide valuable findings toward solving the current ambiguity of the exact mechanism in Ccp1, which could be applied to peroxidases with similar heme pockets. Discerning the feasibility of a no-water peroxidase mechanism in the doublet spin state irrespective of the environment surrounding the heme pocket.![]()
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Affiliation(s)
- Mohamed M Aboelnga
- Chemistry Department, Faculty of Science, Damietta University New Damietta 34517 Egypt
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9
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Shahbazi Farahani F, Rahmanifar MS, Noori A, El-Kady MF, Hassani N, Neek-Amal M, Kaner RB, Mousavi MF. Trilayer Metal-Organic Frameworks as Multifunctional Electrocatalysts for Energy Conversion and Storage Applications. J Am Chem Soc 2022; 144:3411-3428. [PMID: 35167746 DOI: 10.1021/jacs.1c10963] [Citation(s) in RCA: 62] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The need for enhanced energy storage and improved catalysts has led researchers to explore advanced functional materials for sustainable energy production and storage. Herein, we demonstrate a reductive electrosynthesis approach to prepare a layer-by-layer (LbL) assembled trimetallic Fe-Co-Ni metal-organic framework (MOF) in which the metal cations within each layer or at the interface of the two layers are linked to one another by bridging 2-amino-1,4-benzenedicarboxylic acid linkers. Tailoring catalytically active sites in an LbL fashion affords a highly porous material that exhibits excellent trifunctional electrocatalytic activities toward the hydrogen evolution reaction (ηj=10 = 116 mV), oxygen evolution reaction (ηj=10 = 254 mV), as well as oxygen reduction reaction (half-wave potential = 0.75 V vs reference hydrogen electrode) in alkaline solutions. The dispersion-corrected density functional theory calculations suggest that the prominent catalytic activity of the LbL MOF toward the HER, OER, and ORR is due to the initial negative adsorption energy of water on the metal nodes and the elongated O-H bond length of the H2O molecule. The Fe-Co-Ni MOF-based Zn-air battery exhibits a remarkable energy storage performance and excellent cycling stability of over 700 cycles that outperform the commercial noble metal benchmarks. When assembled in an asymmetric device configuration, the activated carbon||Fe-Co-Ni MOF supercapacitor provides a superb specific energy and a power of up to 56.2 W h kg-1 and 42.2 kW kg-1, respectively. This work offers not only a novel approach to prepare an LbL assembled multimetallic MOF but also provides a benchmark for a multifunctional electrocatalyst for water splitting and Zn-air batteries.
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Affiliation(s)
- Fatemeh Shahbazi Farahani
- Department of Chemistry, Faculty of Basic Sciences, Tarbiat Modares University, Tehran 14117-13116, P.O. Box 14115-175, Iran
| | | | - Abolhassan Noori
- Department of Chemistry, Faculty of Basic Sciences, Tarbiat Modares University, Tehran 14117-13116, P.O. Box 14115-175, Iran
| | - Maher F El-Kady
- Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, California 90095, United States
| | - Nasim Hassani
- Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran 16788-15811, P.O. Box: 16875-163, Iran
| | - Mehdi Neek-Amal
- Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran 16788-15811, P.O. Box: 16875-163, Iran.,Department of Physics, University of Antwerp, Groenenborgerlaan 171, Antwerp B-2020, Belgium
| | - Richard B Kaner
- Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, California 90095, United States.,Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095, United States
| | - Mir F Mousavi
- Department of Chemistry, Faculty of Basic Sciences, Tarbiat Modares University, Tehran 14117-13116, P.O. Box 14115-175, Iran
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10
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Saiz F, Bernasconi L. Catalytic properties of the ferryl ion in the solid state: a computational review. Catal Sci Technol 2022. [DOI: 10.1039/d2cy00200k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review summarises the last findings in the emerging field of heterogeneous catalytic oxidation of light alkanes by ferryl species supported on solid-state systems such as the conversion of methane into methanol by FeO-MOF74.
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Affiliation(s)
- Fernan Saiz
- ALBA Synchrotron, Carrer de la Llum 2-26, Cerdanyola del Valles 08290, Spain
| | - Leonardo Bernasconi
- Center for Research Computing and Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
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11
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Schröder GC, Meilleur F. Metalloprotein catalysis: structural and mechanistic insights into oxidoreductases from neutron protein crystallography. Acta Crystallogr D Struct Biol 2021; 77:1251-1269. [PMID: 34605429 PMCID: PMC8489226 DOI: 10.1107/s2059798321009025] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 08/31/2021] [Indexed: 11/11/2022] Open
Abstract
Metalloproteins catalyze a range of reactions, with enhanced chemical functionality due to their metal cofactor. The reaction mechanisms of metalloproteins have been experimentally characterized by spectroscopy, macromolecular crystallography and cryo-electron microscopy. An important caveat in structural studies of metalloproteins remains the artefacts that can be introduced by radiation damage. Photoreduction, radiolysis and ionization deriving from the electromagnetic beam used to probe the structure complicate structural and mechanistic interpretation. Neutron protein diffraction remains the only structural probe that leaves protein samples devoid of radiation damage, even when data are collected at room temperature. Additionally, neutron protein crystallography provides information on the positions of light atoms such as hydrogen and deuterium, allowing the characterization of protonation states and hydrogen-bonding networks. Neutron protein crystallography has further been used in conjunction with experimental and computational techniques to gain insight into the structures and reaction mechanisms of several transition-state metal oxidoreductases with iron, copper and manganese cofactors. Here, the contribution of neutron protein crystallography towards elucidating the reaction mechanism of metalloproteins is reviewed.
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Affiliation(s)
- Gabriela C. Schröder
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Flora Meilleur
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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12
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Lee JL, Ross DL, Barman SK, Ziller JW, Borovik AS. C-H Bond Cleavage by Bioinspired Nonheme Metal Complexes. Inorg Chem 2021; 60:13759-13783. [PMID: 34491738 DOI: 10.1021/acs.inorgchem.1c01754] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The functionalization of C-H bonds is one of the most challenging transformations in synthetic chemistry. In biology, these processes are well-known and are achieved with a variety of metalloenzymes, many of which contain a single metal center within their active sites. The most well studied are those with Fe centers, and the emerging experimental data show that high-valent iron oxido species are the intermediates responsible for cleaving the C-H bond. This Forum Article describes the state of this field with an emphasis on nonheme Fe enzymes and current experimental results that provide insights into the properties that make these species capable of C-H bond cleavage. These parameters are also briefly considered in regard to manganese oxido complexes and Cu-containing metalloenzymes. Synthetic iron oxido complexes are discussed to highlight their utility as spectroscopic and mechanistic probes and reagents for C-H bond functionalization. Avenues for future research are also examined.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Dolores L Ross
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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13
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Ledray AP, Mittra K, Green MT. NRVS investigation of ascorbate peroxidase compound II: Observation of Iron(IV)oxo stretching. J Inorg Biochem 2021; 224:111548. [PMID: 34481347 DOI: 10.1016/j.jinorgbio.2021.111548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/07/2021] [Accepted: 07/13/2021] [Indexed: 11/18/2022]
Abstract
The protonation state of ascorbate peroxidase compound II (APX-II) has been a subject of debate. A combined X-ray/neutron crystallographic study reported that APX-II is best described as an iron(IV)hydroxide species with an FeO distance of 1.88 Å (Kwon, et al. Nat Commun2016, 7, 13,445), while X-ray absorption spectroscopy (XAS) experiments (utilizing extended X-ray absorption fine structure (EXAFS) and pre-edge analyses) indicate APX-II is an authentic iron(IV)oxo species with an FeO distance 1.68 Å (Ledray, et al. Journal of the American Chemical Society2020,142, 20,419). Previous debates concerning ferryl protonation states have been resolved through the application of Badger's rule, which correlates FeO bond distances with FeO vibrational frequencies. To obtain the required vibrational data, we have collected Nuclear Resonance Vibrational Spectroscopy (NRVS) data for APX-II. We observe a broad vibrational feature in the range associated with iron(IV)oxo stretching (700-800 cm-1). This feature appears to have two peaks at 732 cm-1 and 770 cm-1, corresponding to FeO distances of 1.69 and 1.67 Å, respectively. The broad vibrational envelope and the presence of multiple resonances could reflect a distribution of hydrogen bonding interactions within the active-site pocket.
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Affiliation(s)
- Aaron P Ledray
- Department of Chemistry, University of California, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Kaustuv Mittra
- Department of Chemistry, University of California, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Michael T Green
- Department of Chemistry, University of California, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
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14
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Lučić M, Wilson MT, Svistunenko DA, Owen RL, Hough MA, Worrall JAR. Aspartate or arginine? Validated redox state X-ray structures elucidate mechanistic subtleties of Fe IV = O formation in bacterial dye-decolorizing peroxidases. J Biol Inorg Chem 2021; 26:743-761. [PMID: 34477969 PMCID: PMC8463360 DOI: 10.1007/s00775-021-01896-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/23/2021] [Indexed: 11/26/2022]
Abstract
Structure determination of proteins and enzymes by X-ray crystallography remains the most widely used approach to complement functional and mechanistic studies. Capturing the structures of intact redox states in metalloenzymes is critical for assigning the chemistry carried out by the metal in the catalytic cycle. Unfortunately, X-rays interact with protein crystals to generate solvated photoelectrons that can reduce redox active metals and hence change the coordination geometry and the coupled protein structure. Approaches to mitigate such site-specific radiation damage continue to be developed, but nevertheless application of such approaches to metalloenzymes in combination with mechanistic studies are often overlooked. In this review, we summarize our recent structural and kinetic studies on a set of three heme peroxidases found in the bacterium Streptomyces lividans that each belong to the dye decolourizing peroxidase (DyP) superfamily. Kinetically, each of these DyPs has a distinct reactivity with hydrogen peroxide. Through a combination of low dose synchrotron X-ray crystallography and zero dose serial femtosecond X-ray crystallography using an X-ray free electron laser (XFEL), high-resolution structures with unambiguous redox state assignment of the ferric and ferryl (FeIV = O) heme species have been obtained. Experiments using stopped-flow kinetics, solvent-isotope exchange and site-directed mutagenesis with this set of redox state validated DyP structures have provided the first comprehensive kinetic and structural framework for how DyPs can modulate their distal heme pocket Asp/Arg dyad to use either the Asp or the Arg to facilitate proton transfer and rate enhancement of peroxide heterolysis.
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Affiliation(s)
- Marina Lučić
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Dimitri A Svistunenko
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Robin L Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, Oxfordshire, UK
| | - Michael A Hough
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Jonathan A R Worrall
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK.
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15
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Ortmayer M, Hardy FJ, Quesne MG, Fisher K, Levy C, Heyes DJ, Catlow CRA, de Visser SP, Rigby SEJ, Hay S, Green AP. A Noncanonical Tryptophan Analogue Reveals an Active Site Hydrogen Bond Controlling Ferryl Reactivity in a Heme Peroxidase. JACS AU 2021; 1:913-918. [PMID: 34337604 PMCID: PMC8317151 DOI: 10.1021/jacsau.1c00145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nature employs high-energy metal-oxo intermediates embedded within enzyme active sites to perform challenging oxidative transformations with remarkable selectivity. Understanding how different local metal-oxo coordination environments control intermediate reactivity and catalytic function is a long-standing objective. However, conducting structure-activity relationships directly in active sites has proven challenging due to the limited range of amino acid substitutions achievable within the constraints of the genetic code. Here, we use an expanded genetic code to examine the impact of hydrogen bonding interactions on ferryl heme structure and reactivity, by replacing the N-H group of the active site Trp51 of cytochrome c peroxidase by an S atom. Removal of a single hydrogen bond stabilizes the porphyrin π-cation radical state of CcP W191F compound I. In contrast, this modification leads to more basic and reactive neutral ferryl heme states, as found in CcP W191F compound II and the wild-type ferryl heme-Trp191 radical pair of compound I. This increased reactivity manifests in a >60-fold activity increase toward phenolic substrates but remarkably has negligible effects on oxidation of the biological redox partner cytc. Our data highlight how Trp51 tunes the lifetimes of key ferryl intermediates and works in synergy with the redox active Trp191 and a well-defined substrate binding site to regulate catalytic function. More broadly, this work shows how noncanonical substitutions can advance our understanding of active site features governing metal-oxo structure and reactivity.
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Affiliation(s)
- Mary Ortmayer
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Florence J. Hardy
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Matthew G. Quesne
- Research
Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxon OX11 0FA, United
Kingdom
- Cardiff
University, School of Chemistry, Main Building, Park Place, Cardiff CF10
3AT, United Kingdom
| | - Karl Fisher
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Colin Levy
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Derren J. Heyes
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - C. Richard A. Catlow
- Research
Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxon OX11 0FA, United
Kingdom
- Cardiff
University, School of Chemistry, Main Building, Park Place, Cardiff CF10
3AT, United Kingdom
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, 20 Gordon Street, London, Western Central 1H 0AJ, United Kingdom
| | - Sam P. de Visser
- Department
of Chemical Engineering and Analytical Science & Manchester Institute
of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Stephen E. J. Rigby
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Sam Hay
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | - Anthony P. Green
- Department
of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
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16
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Mukherjee G, Satpathy JK, Bagha UK, Mubarak MQE, Sastri CV, de Visser SP. Inspiration from Nature: Influence of Engineered Ligand Scaffolds and Auxiliary Factors on the Reactivity of Biomimetic Oxidants. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01993] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Jagnyesh K. Satpathy
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Umesh K. Bagha
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - M. Qadri E. Mubarak
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Fakulti Sains dan Teknologi, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800 Nilai, Negeri Sembilan Malaysia
| | - Chivukula V. Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Sam P. de Visser
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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17
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Kwon H, Basran J, Pathak C, Hussain M, Freeman SL, Fielding AJ, Bailey AJ, Stefanou N, Sparkes HA, Tosha T, Yamashita K, Hirata K, Murakami H, Ueno G, Ago H, Tono K, Yamamoto M, Sawai H, Shiro Y, Sugimoto H, Raven EL, Moody PCE. XFEL Crystal Structures of Peroxidase Compound II. Angew Chem Int Ed Engl 2021; 60:14578-14585. [PMID: 33826799 PMCID: PMC8251747 DOI: 10.1002/anie.202103010] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Indexed: 01/07/2023]
Abstract
Oxygen activation in all heme enzymes requires the formation of high oxidation states of iron, usually referred to as ferryl heme. There are two known intermediates: Compound I and Compound II. The nature of the ferryl heme-and whether it is an FeIV =O or FeIV -OH species-is important for controlling reactivity across groups of heme enzymes. The most recent evidence for Compound I indicates that the ferryl heme is an unprotonated FeIV =O species. For Compound II, the nature of the ferryl heme is not unambiguously established. Here, we report 1.06 Å and 1.50 Å crystal structures for Compound II intermediates in cytochrome c peroxidase (CcP) and ascorbate peroxidase (APX), collected using the X-ray free electron laser at SACLA. The structures reveal differences between the two peroxidases. The iron-oxygen bond length in CcP (1.76 Å) is notably shorter than in APX (1.87 Å). The results indicate that the ferryl species is finely tuned across Compound I and Compound II species in closely related peroxidase enzymes. We propose that this fine-tuning is linked to the functional need for proton delivery to the heme.
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Affiliation(s)
- Hanna Kwon
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Jaswir Basran
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
| | - Chinar Pathak
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
| | - Mahdi Hussain
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
| | - Samuel L. Freeman
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Alistair J. Fielding
- Centre for Natural Products Discovery, Pharmacy and Biomolecular SciencesLiverpool John Moores UniversityJames Parsons Building, Byrom StreetLiverpoolL3 3AFUK
| | - Anna J. Bailey
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Natalia Stefanou
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Hazel A. Sparkes
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | | | - Keitaro Yamashita
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
- Present address: MRC Laboratory of Molecular BiologyFrancis Crick Avenue, Cambridge Biomedical CampusCambridgeCB1 0QHUK
| | - Kunio Hirata
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
| | - Hironori Murakami
- Japan Synchrotron Radiation Research Institute1-1-1 KoutoSayoHyogo679-5198Japan
| | - Go Ueno
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
| | - Hideo Ago
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute1-1-1 KoutoSayoHyogo679-5198Japan
| | | | - Hitomi Sawai
- Graduate School of Life ScienceUniversity of Hyogo3-2-1 Kouto, Kamigori-choAko-gunHyogo678-1297Japan
| | - Yoshitsugu Shiro
- Graduate School of Life ScienceUniversity of Hyogo3-2-1 Kouto, Kamigori-choAko-gunHyogo678-1297Japan
| | | | - Emma L. Raven
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Peter C. E. Moody
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
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18
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Kwon H, Basran J, Pathak C, Hussain M, Freeman SL, Fielding AJ, Bailey AJ, Stefanou N, Sparkes HA, Tosha T, Yamashita K, Hirata K, Murakami H, Ueno G, Ago H, Tono K, Yamamoto M, Sawai H, Shiro Y, Sugimoto H, Raven EL, Moody PCE. XFEL Crystal Structures of Peroxidase Compound II. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:14699-14706. [PMID: 38505375 PMCID: PMC10947387 DOI: 10.1002/ange.202103010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Indexed: 03/21/2024]
Abstract
Oxygen activation in all heme enzymes requires the formation of high oxidation states of iron, usually referred to as ferryl heme. There are two known intermediates: Compound I and Compound II. The nature of the ferryl heme-and whether it is an FeIV=O or FeIV-OH species-is important for controlling reactivity across groups of heme enzymes. The most recent evidence for Compound I indicates that the ferryl heme is an unprotonated FeIV=O species. For Compound II, the nature of the ferryl heme is not unambiguously established. Here, we report 1.06 Å and 1.50 Å crystal structures for Compound II intermediates in cytochrome c peroxidase (CcP) and ascorbate peroxidase (APX), collected using the X-ray free electron laser at SACLA. The structures reveal differences between the two peroxidases. The iron-oxygen bond length in CcP (1.76 Å) is notably shorter than in APX (1.87 Å). The results indicate that the ferryl species is finely tuned across Compound I and Compound II species in closely related peroxidase enzymes. We propose that this fine-tuning is linked to the functional need for proton delivery to the heme.
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Affiliation(s)
- Hanna Kwon
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Jaswir Basran
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
| | - Chinar Pathak
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
| | - Mahdi Hussain
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
| | - Samuel L. Freeman
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Alistair J. Fielding
- Centre for Natural Products Discovery, Pharmacy and Biomolecular SciencesLiverpool John Moores UniversityJames Parsons Building, Byrom StreetLiverpoolL3 3AFUK
| | - Anna J. Bailey
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Natalia Stefanou
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Hazel A. Sparkes
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | | | - Keitaro Yamashita
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
- Present address: MRC Laboratory of Molecular BiologyFrancis Crick Avenue, Cambridge Biomedical CampusCambridgeCB1 0QHUK
| | - Kunio Hirata
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
| | - Hironori Murakami
- Japan Synchrotron Radiation Research Institute1-1-1 KoutoSayoHyogo679-5198Japan
| | - Go Ueno
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
| | - Hideo Ago
- RIKEN SPring-8 Center1-1-1 KoutoSayoHyogo679-5148Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute1-1-1 KoutoSayoHyogo679-5198Japan
| | | | - Hitomi Sawai
- Graduate School of Life ScienceUniversity of Hyogo3-2-1 Kouto, Kamigori-choAko-gunHyogo678-1297Japan
| | - Yoshitsugu Shiro
- Graduate School of Life ScienceUniversity of Hyogo3-2-1 Kouto, Kamigori-choAko-gunHyogo678-1297Japan
| | | | - Emma L. Raven
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
| | - Peter C. E. Moody
- Department of Molecular and Cell Biology and Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLancaster RoadLeicesterLE1 7RHUK
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19
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Roos G, Harvey JN. Histidine versus Cysteine-Bearing Heme-Dependent Halogen Peroxidases: Parallels and Differences for Cl - Oxidation. J Phys Chem B 2021; 125:74-85. [PMID: 33350832 DOI: 10.1021/acs.jpcb.0c09409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The homodimeric myeloperoxidase (MPO) features a histidine as a proximal ligand and a sulfonium linkage covalently attaching the heme porphyrin ring to the protein. MPO is able to catalyze Cl- oxidation with about the same efficiency as chloroperoxidase at pH 7.0. In this study, we seek to explore the parallels and differences between the histidine and cysteine heme-dependent halogen peroxidases. Transition states, reaction barriers, and relevant thermodynamic properties are calculated on protein models. Together with electronic structure calculations, it gives an overview of the reaction mechanisms and of the factors that determine the selectivity between one- and two-electron paths. Conclusions point to the innate oxidizing nature of MPO with the ester and sulfonium linkages hiking up the reactivity to enable chloride oxidation. The installation of a deprotonated imidazolate as a proximal ligand does not shift the equilibrium from one- to two-electron events without influencing the chemistry of the oxidation reaction.
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Affiliation(s)
- Goedele Roos
- UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, University of Lille, CNRS, UMR 8576, F-59000 Lille, France
| | - Jeremy N Harvey
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
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20
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Ledray AP, Krest CM, Yosca TH, Mittra K, Green MT. Ascorbate Peroxidase Compound II Is an Iron(IV) Oxo Species. J Am Chem Soc 2020; 142:10.1021/jacs.0c09108. [PMID: 33170000 PMCID: PMC8107191 DOI: 10.1021/jacs.0c09108] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The protonation state of the iron(IV) oxo (or ferryl) form of ascorbate peroxidase compound II (APX-II) is a subject of debate. It has been reported that this intermediate is best described as an iron(IV) hydroxide species. Neutron diffraction data obtained from putative APX-II crystals indicate a protonated oxygenic ligand at 1.88 Å from the heme iron. This finding, if correct, would be unprecedented. A basic iron(IV) oxo species has yet to be spectroscopically observed in a histidine-ligated heme enzyme. The importance of ferryl basicity lies in its connection to our fundamental understanding of C-H bond activation. Basic ferryl species have been proposed to facilitate the oxidation of inert C-H bonds, reactions that are unknown for histidine-ligated hemes enzymes. To provide further insight into the protonation status of APX-II, we examined the intermediate using a combination of Mössbauer and X-ray absorption spectroscopies. Our data indicate that APX-II is an iron(IV) oxo species with an Fe-O bond distance of 1.68 Å, a K-edge pre-edge absorption of 18 units, and Mössbauer parameters of ΔEq = 1.65 mm/s and δ = 0.03 mm/s.
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Affiliation(s)
- Aaron P Ledray
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Courtney M Krest
- Roach & Associates, Limited Liability Company, Seymour, Wisconsin 54942, United States
| | - Timothy H Yosca
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Kaustuv Mittra
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Michael T Green
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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21
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Mukherjee M, Dey A. Catalytic C–H Bond Oxidation Using Dioxygen by Analogues of Heme Superoxide. Inorg Chem 2020; 59:7415-7425. [DOI: 10.1021/acs.inorgchem.9b03767] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Manjistha Mukherjee
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
| | - Abhishek Dey
- School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India
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22
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Shimada A, Etoh Y, Kitoh-Fujisawa R, Sasaki A, Shinzawa-Itoh K, Hiromoto T, Yamashita E, Muramoto K, Tsukihara T, Yoshikawa S. X-ray structures of catalytic intermediates of cytochrome c oxidase provide insights into its O 2 activation and unidirectional proton-pump mechanisms. J Biol Chem 2020; 295:5818-5833. [PMID: 32165497 PMCID: PMC7186171 DOI: 10.1074/jbc.ra119.009596] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 03/09/2020] [Indexed: 01/07/2023] Open
Abstract
Cytochrome c oxidase (CcO) reduces O2 to water, coupled with a proton-pumping process. The structure of the O2-reduction site of CcO contains two reducing equivalents, Fe a32+ and CuB1+, and suggests that a peroxide-bound state (Fe a33+-O--O--CuB2+) rather than an O2-bound state (Fe a32+-O2) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fe a32+-O2, whereas Fe a33+-O--O--CuB2+ is undetectable. Based on X-ray structures of static noncatalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N- and P-side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 Å resolution. A 1.70 Å Fe-O distance of the ferryl center could best be described as Fe a34+ = O2-, not as Fe a34+-OH- The distance suggests an ∼800-cm-1 Raman stretching band. We found an interstitial water molecule that could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fe a33+-O--O--CuB2+ state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition.
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Affiliation(s)
- Atsuhiro Shimada
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan
| | - Yuki Etoh
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan
| | - Rika Kitoh-Fujisawa
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan
| | - Ai Sasaki
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan
| | - Kyoko Shinzawa-Itoh
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan; Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan
| | - Takeshi Hiromoto
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan
| | - Eiki Yamashita
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kazumasa Muramoto
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan.
| | - Tomitake Tsukihara
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan; Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Shinya Yoshikawa
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan; Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akoh, Hyogo 678-1297, Japan.
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23
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Shi J, Guo Y, Xie F, Chen Q, Zhang M. Redox‐Active Ligand Assisted Catalytic Water Oxidation by a Ru
IV
=O Intermediate. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201910614] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Jing Shi
- Center of Basic Molecular Science (CBMS) Department of Chemistry Tsinghua University Beijing 100084 China
| | - Yu‐Hua Guo
- Center of Basic Molecular Science (CBMS) Department of Chemistry Tsinghua University Beijing 100084 China
| | - Fei Xie
- Center of Basic Molecular Science (CBMS) Department of Chemistry Tsinghua University Beijing 100084 China
| | - Qi‐Fa Chen
- Center of Basic Molecular Science (CBMS) Department of Chemistry Tsinghua University Beijing 100084 China
| | - Ming‐Tian Zhang
- Center of Basic Molecular Science (CBMS) Department of Chemistry Tsinghua University Beijing 100084 China
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24
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Shi J, Guo YH, Xie F, Chen QF, Zhang MT. Redox-Active Ligand Assisted Catalytic Water Oxidation by a Ru IV =O Intermediate. Angew Chem Int Ed Engl 2020; 59:4000-4008. [PMID: 31880387 DOI: 10.1002/anie.201910614] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/25/2019] [Indexed: 01/15/2023]
Abstract
Water splitting is one of the most promising solutions for storing solar energy in a chemical bond. Water oxidation is still the bottleneck step because of its inherent difficulty and the limited understanding of the O-O bond formation mechanism. Molecular catalysts provide a platform for understanding this process in depth and have received wide attention since the first Ru-based catalyst was reported in 1982. RuV =O is considered a key intermediate to initiate the O-O bond formation through either a water nucleophilic attack (WNA) pathway or a bimolecular coupling (I2M) pathway. Herein, we report a Ru-based catalyst that displays water oxidation reactivity with RuIV =(O) with the help of a redox-active ligand at pH 7.0. The results of electrochemical studies and DFT calculations disclose that ligand oxidation could significantly improve the reactivity of RuIV =O toward water oxidation. Under these conditions, sustained water oxidation catalysis occurs at reasonable rates with low overpotential (ca. 183 mV).
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Affiliation(s)
- Jing Shi
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yu-Hua Guo
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Fei Xie
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Qi-Fa Chen
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Ming-Tian Zhang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
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25
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Dent MR, Milbauer MW, Hunt AP, Aristov MM, Guzei IA, Lehnert N, Burstyn JN. Electron Paramagnetic Resonance Spectroscopy as a Probe of Hydrogen Bonding in Heme-Thiolate Proteins. Inorg Chem 2019; 58:16011-16027. [PMID: 31786931 PMCID: PMC11160398 DOI: 10.1021/acs.inorgchem.9b02506] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Despite utilizing a common cofactor binding motif, hemoproteins bearing a cysteine-derived thiolate ligand (heme-thiolate proteins) are involved in a diverse array of biological processes ranging from drug metabolism to transcriptional regulation. Though the origin of heme-thiolate functional divergence is not well understood, growing evidence suggests that the hydrogen bonding (H-bonding) environment surrounding the Fe-coordinating thiolate influences protein function. Outside of X-ray crystallography, few methods exist to characterize these critical H-bonding interactions. Electron paramagnetic resonance (EPR) spectra of heme-thiolate proteins bearing a six-coordinate, Fe(III) heme exhibit uniquely narrow low-spin (S = 1/2), rhombic signals, which are sensitive to changes in the heme-thiolate H-bonding environment. To establish a well-defined relationship between the magnitude of g-value dispersion in this unique EPR signal and the strength of the heme-thiolate H-bonding environment, we synthesized and characterized of a series of six-coordinate, aryl-thiolate-ligated Fe(III) porphyrin complexes bearing a tunable intramolecular H-bond. Spectroscopic investigation of these complexes revealed a direct correlation between H-bond strength and g-value dispersion in the rhombic EPR signal. Using density functional theory (DFT), we elucidated the electronic origins of the narrow, rhombic EPR signal in heme-thiolates, which arises from an Fe-S pπ-dπ bonding interaction. Computational analysis of the intramolecularly H-bonded heme-thiolate models revealed that H-bond donation to the coordinating thiolate reduces thiolate donor strength and weakens this Fe-S interaction, giving rise to larger g-value dispersion. By defining the relationship between heme-thiolate electronic structure and rhombic EPR signal, it is possible to compare thiolate donor strengths among heme-thiolate proteins through analysis of low-spin, Fe(III) EPR spectra. Thus, this study establishes EPR spectroscopy as a valuable tool for exploring how second coordination sphere effects influence heme-thiolate protein function.
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Affiliation(s)
- Matthew R. Dent
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Michael W. Milbauer
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Andrew P. Hunt
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Michael M. Aristov
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Ilia A. Guzei
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Judith N. Burstyn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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26
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Gordon JB, Vilbert AC, DiMucci IM, MacMillan SN, Lancaster KM, Moënne-Loccoz P, Goldberg DP. Activation of Dioxygen by a Mononuclear Nonheme Iron Complex: Sequential Peroxo, Oxo, and Hydroxo Intermediates. J Am Chem Soc 2019; 141:17533-17547. [PMID: 31647656 DOI: 10.1021/jacs.9b05274] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The activation of dioxygen by FeII(Me3TACN)(S2SiMe2) (1) is reported. Reaction of 1 with O2 at -135 °C in 2-MeTHF generates a thiolate-ligated (peroxo)diiron complex FeIII2(O2)(Me3TACN)2(S2SiMe2)2 (2) that was characterized by UV-vis (λmax = 300, 390, 530, 723 nm), Mössbauer (δ = 0.53, |ΔEQ| = 0.76 mm s-1), resonance Raman (RR) (ν(O-O) = 849 cm-1), and X-ray absorption (XAS) spectroscopies. Complex 2 is distinct from the outer-sphere oxidation product 1ox (UV-vis (λmax = 435, 520, 600 nm), Mössbauer (δ = 0.45, |ΔEQ| = 3.6 mm s-1), and EPR (S = 5/2, g = [6.38, 5.53, 1.99])), obtained by one-electron oxidation of 1. Cleavage of the peroxo O-O bond can be initiated either photochemically or thermally to produce a new species assigned as an FeIV(O) complex, FeIV(O)(Me3TACN)(S2SiMe2) (3), which was identified by UV-vis (λmax = 385, 460, 890 nm), Mössbauer (δ = 0.21, |ΔEQ| = 1.57 mm s-1), RR (ν(FeIV═O) = 735 cm-1), and X-ray absorption spectroscopies, as well as reactivity patterns. Reaction of 3 at low temperature with H atom donors gives a new species, FeIII(OH)(Me3TACN)(S2SiMe2) (4). Complex 4 was independently synthesized from 1 by the stoichiometric addition of a one-electron oxidant and a hydroxide source. This work provides a rare example of dioxygen activation at a mononuclear nonheme iron(II) complex that produces both FeIII-O-O-FeIII and FeIV(O) species in the same reaction with O2. It also demonstrates the feasibility of forming Fe/O2 intermediates with strongly donating sulfur ligands while avoiding immediate sulfur oxidation.
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Affiliation(s)
- Jesse B Gordon
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Ida M DiMucci
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry , Oregon Health & Science University , Portland , Oregon 97239 , United States
| | - David P Goldberg
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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27
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Ehudin MA, Quist DA, Karlin KD. Enhanced Rates of C-H Bond Cleavage by a Hydrogen-Bonded Synthetic Heme High-Valent Iron(IV) Oxo Complex. J Am Chem Soc 2019; 141:12558-12569. [PMID: 31318198 PMCID: PMC6734939 DOI: 10.1021/jacs.9b01253] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Secondary coordination sphere interactions are critical in facilitating the formation, stabilization, and enhanced reactivity of high-valent oxidants required for essential biochemical processes. Herein, we compare the C-H bond oxidizing capabilities of spectroscopically characterized synthetic heme iron(IV) oxo complexes, F8Cmpd-II (F8 = tetrakis(2,6-difluorophenyl)porphyrinate), and a 2,6-lutidinium triflate (LutH+) Lewis acid adduct involving ferryl O-atom hydrogen-bonding, F8Cmpd-II(LutH+). Second-order rate constants utilizing C-H and C-D substrates were obtained by UV-vis spectroscopic monitoring, while products were characterized and quantified by EPR spectroscopy and gas chromatography (GC). With xanthene, F8Cmpd-II(LutH+) reacts 40 times faster (k2 = 14.2 M-1 s-1; -90 °C) than does F8Cmpd-II, giving bixanthene plus xanthone and the heme product [F8FeIIIOH2]+. For substrates with greater C-H bond dissociation energies (BDEs) F8Cmpd-II(LutH+) reacts with the second order rate constants k2(9,10-dihydroanthracene; DHA) = 0.485 M-1 s-1 and k2(fluorene) = 0.102 M-1 s-1 (-90 °C); by contrast, F8Cmpd-II is unreactive toward these substrates. For xanthene vs xanthene-(d2), large, nonclassical deuterium kinetic isotope effects are roughly estimated for both F8Cmpd-II and F8Cmpd-II(LutH+). The deuterated H-bonded analog, F8Cmpd-II(LutD+), was also prepared; for the reaction with DHA, an inverse KIE (compared to F8Cmpd-II(LutH+)) was observed. This work originates/inaugurates experimental investigation of the reactivity of authentic H-bonded heme-based FeIV═O compounds, critically establishing the importance of oxo H-bonding (or protonation) in heme complexes and enzyme active sites.
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Affiliation(s)
- Melanie A. Ehudin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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28
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Ehudin MA, Gee LB, Sabuncu S, Braun A, Moenne-Loccoz P, Hedman B, Hodgson KO, Solomon EI, Karlin KD. Tuning the Geometric and Electronic Structure of Synthetic High-Valent Heme Iron(IV)-Oxo Models in the Presence of a Lewis Acid and Various Axial Ligands. J Am Chem Soc 2019; 141:5942-5960. [PMID: 30860832 PMCID: PMC6611672 DOI: 10.1021/jacs.9b00795] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
High-valent ferryl species (e.g., (Por)FeIV═O, Cmpd-II) are observed or proposed key oxidizing intermediates in the catalytic cycles of heme-containing enzymes (P-450s, peroxidases, catalases, and cytochrome c oxidase) involved in biological respiration and oxidative metabolism. Herein, various axially ligated iron(IV)-oxo complexes were prepared to examine the influence of the identity of the base. These were generated by addition of various axial ligands (1,5-dicyclohexylimidazole (DCHIm), a tethered-imidazole system, and sodium derivatives of 3,5-dimethoxyphenolate and imidazolate). Characterization was carried out via UV-vis, electron paramagnetic resonance (EPR), 57Fe Mössbauer, Fe X-ray absorption (XAS), and 54/57Fe resonance Raman (rR) spectroscopies to confirm their formation and compare the axial ligand perturbation on the electronic and geometric structures of these heme iron(IV)-oxo species. Mössbauer studies confirmed that the axially ligated derivatives were iron(IV) and six-coordinate complexes. XAS and 54/57Fe rR data correlated with slight elongation of the iron-oxo bond with increasing donation from the axial ligands. The first reported synthetic H-bonded iron(IV)-oxo heme systems were made in the presence of the protic Lewis acid, 2,6-lutidinium triflate (LutH+), with (or without) DCHIm. Mössbauer, rR, and XAS spectroscopic data indicated the formation of molecular Lewis acid ferryl adducts (rather than full protonation). The reduction potentials of these novel Lewis acid adducts were bracketed through addition of outer-sphere reductants. The oxidizing capabilities of the ferryl species with or without Lewis acid vary drastically; addition of LutH+ to F8Cmpd-II (F8 = tetrakis(2,6-difluorophenyl)porphyrinate) increased its reduction potential by more than 890 mV, experimentally confirming that H-bonding interactions can increase the reactivity of ferryl species.
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Affiliation(s)
- Melanie A. Ehudin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Leland B. Gee
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sinan Sabuncu
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239-3098, United States
| | - Augustin Braun
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Pierre Moenne-Loccoz
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239-3098, United States
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Keith O. Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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29
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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30
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Huang X, Groves JT. Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins. Chem Rev 2018; 118:2491-2553. [PMID: 29286645 PMCID: PMC5855008 DOI: 10.1021/acs.chemrev.7b00373] [Citation(s) in RCA: 591] [Impact Index Per Article: 98.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Indexed: 12/20/2022]
Abstract
As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal-oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal-oxo species, are the basis for the various biological functions of O2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron-oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we envision that new enzymatic and synthetic transformations will emerge based on the radical processes mediated by metalloproteins and their synthetic analogs.
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Affiliation(s)
- Xiongyi Huang
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Chemistry, California Institute of Technology, Pasadena, California 91125, United States
| | - John T. Groves
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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31
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Abstract
Aerobic organisms have evolved to activate oxygen from the atmosphere, which allows them to catalyze the oxidation of different kinds of substrates. This activation of oxygen is achieved by a metal center (usually iron or copper) buried within a metalloprotein. In the case of iron-containing heme enzymes, the activation of oxygen is achieved by formation of transient iron-oxo (ferryl) intermediates; these intermediates are called Compound I and Compound II. The Compound I and II intermediates were first discovered in the 1930s in horseradish peroxidase, and it is now known that these same species are used across the family of heme enzymes, which include all of the peroxidases, the heme catalases, the P450s, cytochrome c oxidase, and NO synthase. Many years have passed since the first observations, but establishing the chemical nature of these transient ferryl species remains a fundamental question that is relevant to the reactivity, and therefore the usefulness, of these species in biology. This Account summarizes experiments that were conceived and conducted at Leicester and presents our ideas on the chemical nature, stability, and reactivity of these ferryl heme species. We begin by briefly summarizing the early milestones in the field, from the 1940s and 1950s. We present comparisons between the nature and reactivity of the ferryl species in horseradish peroxidase, cytochrome c peroxidase, and ascorbate peroxidase; and we consider different modes of electron delivery to ferryl heme, from different substrates in different peroxidases. We address the question of whether the ferryl heme is best formulated as an (unprotonated) FeIV═O or as a (protonated) FeIV-OH species. A range of spectroscopic approaches (EXAFS, resonance Raman, Mossbauer, and EPR) have been used over many decades to examine this question, and in the last ten years, X-ray crystallography has also been employed. We describe how information from all of these studies has blended together to create an overall picture, and how the recent application of neutron crystallography has directly identified protonation states and has helped to clarify the precise nature of the ferryl heme in cytochrome c peroxidase and ascorbate peroxidase. We draw comparisons between the Compound I and Compound II species that we have observed in peroxidases with those found in other heme systems, notably the P450s, highlighting possible commonality across these heme ferryl systems. The identification of proton locations from neutron structures of these ferryl species opens the door for understanding the proton translocations that need to occur during O-O bond cleavage.
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Affiliation(s)
- Peter C. E. Moody
- Department
of Molecular and Cell Biology and Leicester Institute of Structural
and Chemical Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, England
| | - Emma L. Raven
- Department
of Chemistry and Leicester Institute of Structural and Chemical Biology, University of Leicester, University Road, Leicester LE1 7RH, U.K
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32
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Lang J, Maréchal A, Couture M, Santolini J. Reaction Intermediates and Molecular Mechanism of Peroxynitrite Activation by NO Synthases. Biophys J 2017; 111:2099-2109. [PMID: 27851935 DOI: 10.1016/j.bpj.2016.05.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 05/26/2016] [Accepted: 05/31/2016] [Indexed: 11/26/2022] Open
Abstract
The activation of the peroxynitrite anion (PN) by hemoproteins, which leads to its detoxification or, on the contrary to the enhancement of its cytotoxic activity, is a reaction of physiological importance that is still poorly understood. It has been known for some years that the reaction of hemoproteins, notably cytochrome P450, with PN leads to the buildup of an intermediate species with a Soret band at ∼435 nm (I435). The nature of this intermediate is, however, debated. On the one hand, I435 has been presented as a compound II species that can be photoactivated to compound I. A competing alternative involves the assignment of I435 to a ferric-nitrosyl species. Similar to cytochromes P450, the buildup of I435 occurs in nitric oxide synthases (NOSs) upon their reaction with excess PN. Interestingly, the NOS isoforms vary in their capacity to detoxify/activate PN, although they all show the buildup of I435. To better understand PN activation/detoxification by heme proteins, a definitive assignment of I435 is needed. Here we used a combination of fine kinetic analysis under specific conditions (pH, PN concentrations, and PN/NOSs ratios) to probe the formation of I435. These studies revealed that I435 is not formed upon homolytic cleavage of the O-O bond of PN, but instead arises from side reactions associated with excess PN. Characterization of I435 by resonance Raman spectroscopy allowed its identification as a ferric iron-nitrosyl complex. Our study indicates that the model used so far to depict PN interactions with hemo-thiolate proteins, i.e., leading to the formation and accumulation of compound II, needs to be reconsidered.
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Affiliation(s)
- Jérôme Lang
- Laboratory of Oxidative Stress and Detoxification, iBiTec-S/I2BC, UMR 9198, CEA-Centre National de la Recherche Scientifique Université Paris Sud, CEA Saclay, Gif-sur-Yvette Cedex, France; Department of Biochemistry, Université Laval, Laval, Québec, Canada
| | - Amandine Maréchal
- Laboratory of Oxidative Stress and Detoxification, iBiTec-S/I2BC, UMR 9198, CEA-Centre National de la Recherche Scientifique Université Paris Sud, CEA Saclay, Gif-sur-Yvette Cedex, France
| | - Manon Couture
- Department of Biochemistry, Université Laval, Laval, Québec, Canada
| | - Jérôme Santolini
- Laboratory of Oxidative Stress and Detoxification, iBiTec-S/I2BC, UMR 9198, CEA-Centre National de la Recherche Scientifique Université Paris Sud, CEA Saclay, Gif-sur-Yvette Cedex, France.
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33
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Yosca TH, Ledray AP, Ngo J, Green MT. A new look at the role of thiolate ligation in cytochrome P450. J Biol Inorg Chem 2017; 22:209-220. [PMID: 28091754 PMCID: PMC5640440 DOI: 10.1007/s00775-016-1430-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 12/14/2016] [Indexed: 10/20/2022]
Abstract
Protonated ferryl (or iron(IV)hydroxide) intermediates have been characterized in several thiolate-ligated heme proteins that are known to catalyze C-H bond activation. The basicity of the ferryl intermediates in these species has been proposed to play a critical role in facilitating this chemistry, allowing hydrogen abstraction at reduction potentials below those that would otherwise lead to oxidative degradation of the enzyme. In this contribution, we discuss the events that led to the assignment and characterization of the unusual iron(IV)hydroxide species, highlighting experiments that provided a quantitative measure of the ferryl basicity, the iron(IV)hydroxide pKa. We then turn to the importance of the iron(IV)hydroxide state, presenting a new way of looking at the role of thiolate ligation in these systems.
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Affiliation(s)
- Timothy H Yosca
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California-Irvine, 4134, Natural Sciences 1, Irvine, CA 92697, USA
| | - Aaron P Ledray
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California-Irvine, 4134, Natural Sciences 1, Irvine, CA 92697, USA
| | - Joanna Ngo
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California-Irvine, 4134, Natural Sciences 1, Irvine, CA 92697, USA
| | - Michael T Green
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California-Irvine, 4134, Natural Sciences 1, Irvine, CA 92697, USA.
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Xue XS, Ji P, Zhou B, Cheng JP. The Essential Role of Bond Energetics in C-H Activation/Functionalization. Chem Rev 2017; 117:8622-8648. [PMID: 28281752 DOI: 10.1021/acs.chemrev.6b00664] [Citation(s) in RCA: 304] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The most fundamental concepts in chemistry are structure, energetics, reactivity and their inter-relationships, which are indispensable for promoting chemistry into a rational science. In this regard, bond energy, the intrinsic determinant directly related to structure and reactivity, should be most essential in serving as a quantitative basis for the design and understanding of organic transformations. Although C-H activation/functionalization have drawn tremendous research attention and flourished during the past decades, understanding the governing rules of bond energetics in these processes is still fragmentary and seems applicable only to limited cases, such as metal-oxo-mediated hydrogen atom abstraction. Despite the complexity of C-H activation/functionalization and the difficulties in measuring bond energies both for the substrates and intermediates, this is definitely a very important issue that should be more generally contemplated. To this end, this review is rooted in the energetic aspects of C-H activation/functionalization, which were previously rarely discussed in detail. Starting with a concise but necessary introduction of various classical methods for measuring heterolytic and homolytic energies for C-H bonds, the present review provides examples that applied the concept and values of C-H bond energy in rationalizing the observations associated with reactivity and/or selectivity in C-H activation/functionalization.
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Affiliation(s)
- Xiao-Song Xue
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin, 300071, China
| | - Pengju Ji
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University , Beijing, 100084, China
| | - Biying Zhou
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, 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 Center of Chemical Science and Engineering, Nankai University , Tianjin, 300071, China
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35
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Yosca TH, Langston MC, Krest CM, Onderko EL, Grove TL, Livada J, Green MT. Spectroscopic Investigations of Catalase Compound II: Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme. J Am Chem Soc 2016; 138:16016-16023. [PMID: 27960340 PMCID: PMC5987761 DOI: 10.1021/jacs.6b09693] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pKa = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pKa in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules.
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Affiliation(s)
- Timothy H. Yosca
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Matthew C. Langston
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Courtney M. Krest
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Elizabeth L. Onderko
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tyler L. Grove
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jovan Livada
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Michael T. Green
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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36
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Huang X, Groves JT. Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C-H activation. J Biol Inorg Chem 2016; 22:185-207. [PMID: 27909920 PMCID: PMC5350257 DOI: 10.1007/s00775-016-1414-3] [Citation(s) in RCA: 195] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/03/2016] [Indexed: 11/24/2022]
Abstract
Since our initial report in 1976, the oxygen rebound mechanism has become the consensus mechanistic feature for an expanding variety of enzymatic C-H functionalization reactions and small molecule biomimetic catalysts. For both the biotransformations and models, an initial hydrogen atom abstraction from the substrate (R-H) by high-valent iron-oxo species (Fen=O) generates a substrate radical and a reduced iron hydroxide, [Fen-1-OH ·R]. This caged radical pair then evolves on a complicated energy landscape through a number of reaction pathways, such as oxygen rebound to form R-OH, rebound to a non-oxygen atom affording R-X, electron transfer of the incipient radical to yield a carbocation, R+, desaturation to form olefins, and radical cage escape. These various flavors of the rebound process, often in competition with each other, give rise to the wide range of C-H functionalization reactions performed by iron-containing oxygenases. In this review, we first recount the history of radical rebound mechanisms, their general features, and key intermediates involved. We will discuss in detail the factors that affect the behavior of the initial caged radical pair and the lifetimes of the incipient substrate radicals. Several representative examples of enzymatic C-H transformations are selected to illustrate how the behaviors of the radical pair [Fen-1-OH ·R] determine the eventual reaction outcome. Finally, we discuss the powerful potential of "radical rebound" processes as a general paradigm for developing novel C-H functionalization reactions with synthetic, biomimetic catalysts. We envision that new chemistry will continue to arise by bridging enzymatic "radical rebound" with synthetic organic chemistry.
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Direct visualization of a Fe(IV)-OH intermediate in a heme enzyme. Nat Commun 2016; 7:13445. [PMID: 27897163 PMCID: PMC5141285 DOI: 10.1038/ncomms13445] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 10/05/2016] [Indexed: 11/21/2022] Open
Abstract
Catalytic heme enzymes carry out a wide range of oxidations in biology. They have in common a mechanism that requires formation of highly oxidized ferryl intermediates. It is these ferryl intermediates that provide the catalytic engine to drive the biological activity. Unravelling the nature of the ferryl species is of fundamental and widespread importance. The essential question is whether the ferryl is best described as a Fe(IV)=O or a Fe(IV)–OH species, but previous spectroscopic and X-ray crystallographic studies have not been able to unambiguously differentiate between the two species. Here we use a different approach. We report a neutron crystal structure of the ferryl intermediate in Compound II of a heme peroxidase; the structure allows the protonation states of the ferryl heme to be directly observed. This, together with pre-steady state kinetic analyses, electron paramagnetic resonance spectroscopy and single crystal X-ray fluorescence, identifies a Fe(IV)–OH species as the reactive intermediate. The structure establishes a precedent for the formation of Fe(IV)–OH in a peroxidase. The nature of the ferryl intermediate generated in reactions catalysed by heme-containing enzymes is uncertain, due to the ambiguity of X-ray crystallography data. Here, the authors apply neutron diffraction, kinetics and other spectroscopy to directly observe a protonated ferryl intermediate in a heme peroxidase.
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38
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Bougher CJ, Abu-Omar MM. Lewis-Acid-assisted Hydrogen Atom Transfer to Manganese(V)-Oxo Corrole through Valence Tautomerization. ChemistryOpen 2016; 5:522-524. [PMID: 28032019 PMCID: PMC5167333 DOI: 10.1002/open.201600117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Indexed: 11/09/2022] Open
Abstract
The kinetics of formation of the valence tautomers (tpfc⋅)MnIV(O−LA)]n+ [where LA=ZnII, CaII, ScIII, YbIII, B(C6F5)3, and trifluoroacetic acid (TFA); tpfc=5,10,15‐tris(pentafluorophenyl) corrole] from (tpfc)MnV(O) were followed by UV/Vis spectroscopy, giving second‐order rate constants ranging over five orders of magnitude from 10−2 for Ca to 103
m−1 s−1 for Sc. Hydrogen atom transfer (HAT) rates from 2,4‐di‐tert‐butyl phenol (2,4‐DTBP) to the various Lewis acid valence tautomers of manganese oxo corrole complexes were evaluated and compared. For LA=TFA, ScIII, or YbIII, the rate constants of HAT were comparable to unactivated (tpfc)MnV(O). However, with LA=B(C6F5)3, ZnII, and CaII, 6‐, 21‐, and 31‐fold rate enhancements were observed, respectively. Remarkably, [(tpfc⋅)MnIV(OCa)]2+ gave the most enhancement despite its rate of formation being the slowest. Comparisons of HAT rate constants among the various Lewis acid tautomers revealed that both size and charge are important. This study underscores how valence may affect the reactivity of high‐valent manganese‐oxo compounds and sheds light on nature's choice of Ca in the activation of Mn‐oxo in the oxygen‐evolving complex.
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Affiliation(s)
- Curt J Bougher
- Department of Chemistry Purdue University 560 Oval Drive West Lafayette IN 47906 USA
| | - Mahdi M Abu-Omar
- Department of Chemistry Purdue University 560 Oval Drive West Lafayette IN 47906 USA; Current address: Department of Chemistry and Biochemistry Department of Chemical Engineering University of California Santa Barbara CA 93106 USA
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Hill EA, Weitz AC, Onderko E, Romero-Rivera A, Guo Y, Swart M, Bominaar EL, Green MT, Hendrich MP, Lacy DC, Borovik AS. Reactivity of an Fe IV-Oxo Complex with Protons and Oxidants. J Am Chem Soc 2016; 138:13143-13146. [PMID: 27647293 PMCID: PMC5110122 DOI: 10.1021/jacs.6b07633] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
High-valent Fe-OH species are often invoked as key intermediates but have only been observed in Compound II of cytochrome P450s. To further address the properties of non-heme FeIV-OH complexes, we demonstrate the reversible protonation of a synthetic FeIV-oxo species containing a tris-urea tripodal ligand. The same protonated FeIV-oxo species can be prepared via oxidation, suggesting that a putative FeV-oxo species was initially generated. Computational, Mössbauer, XAS, and NRVS studies indicate that protonation of the FeIV-oxo complex most likely occurs on the tripodal ligand, which undergoes a structural change that results in the formation of a new intramolecular H-bond with the oxido ligand that aids in stabilizing the protonated adduct. We suggest that similar protonated high-valent Fe-oxo species may occur in the active sites of proteins. This finding further argues for caution when assigning unverified high-valent Fe-OH species to mechanisms.
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Affiliation(s)
- Ethan A. Hill
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, CA 92697
| | - Andrew C. Weitz
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Elizabeth Onderko
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
| | - Adrian Romero-Rivera
- Institut de Química Computacional i Catàlisi & Dept. Química, Universitat de Girona, 17003, Spain
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi & Dept. Química, Universitat de Girona, 17003, Spain
- ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain
| | - Emile L. Bominaar
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Michael T. Green
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, CA 92697
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
| | | | - David C. Lacy
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, CA 92697
| | - A. S. Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, CA 92697
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40
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Davydov R, Im S, Shanmugam M, Gunderson WA, Pearl NM, Hoffman BM, Waskell L. Role of the Proximal Cysteine Hydrogen Bonding Interaction in Cytochrome P450 2B4 Studied by Cryoreduction, Electron Paramagnetic Resonance, and Electron-Nuclear Double Resonance Spectroscopy. Biochemistry 2016; 55:869-83. [PMID: 26750753 DOI: 10.1021/acs.biochem.5b00744] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystallographic studies have shown that the F429H mutation of cytochrome P450 2B4 introduces an H-bond between His429 and the proximal thiolate ligand, Cys436, without altering the protein fold but sharply decreases the enzymatic activity and stabilizes the oxyferrous P450 2B4 complex. To characterize the influence of this hydrogen bond on the states of the catalytic cycle, we have used radiolytic cryoreduction combined with electron paramagnetic resonance (EPR) and (electron-nuclear double resonance (ENDOR) spectroscopy to study and compare their characteristics for wild-type (WT) P450 2B4 and the F429H mutant. (i) The addition of an H-bond to the axial Cys436 thiolate significantly changes the EPR signals of both low-spin and high-spin heme-iron(III) and the hyperfine couplings of the heme-pyrrole (14)N but has relatively little effect on the (1)H ENDOR spectra of the water ligand in the six-coordinate low-spin ferriheme state. These changes indicate that the H-bond introduced between His and the proximal cysteine decreases the extent of S → Fe electron donation and weakens the Fe(III)-S bond. (ii) The added H-bond changes the primary product of cryoreduction of the Fe(II) enzyme, which is trapped in the conformation of the parent Fe(II) state. In the wild-type enzyme, the added electron localizes on the porphyrin, generating an S = (3)/2 state with the anion radical exchange-coupled to the Fe(II). In the mutant, it localizes on the iron, generating an S = (1)/2 Fe(I) state. (iii) The additional H-bond has little effect on g values and (1)H-(14)N hyperfine couplings of the cryogenerated, ferric hydroperoxo intermediate but noticeably slows its decay during cryoannealing. (iv) In both the WT and the mutant enzyme, this decay shows a significant solvent kinetic isotope effect, indicating that the decay reflects a proton-assisted conversion to Compound I (Cpd I). (v) We confirm that Cpd I formed during the annealing of the cryogenerated hydroperoxy intermediate and that it is the active hydroxylating species in both WT P450 2B4 and the F429H mutant. (vi) Our data also indicate that the added H-bond of the mutation diminishes the reactivity of Cpd I.
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Affiliation(s)
- Roman Davydov
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Sangchoul Im
- Department of Anesthesiology, University of Michigan, and VA Medical Center , 2215 Fuller Road, Ann Arbor, Michigan 48105, United States
| | - Muralidharan Shanmugam
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - William A Gunderson
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Naw May Pearl
- Department of Anesthesiology, University of Michigan, and VA Medical Center , 2215 Fuller Road, Ann Arbor, Michigan 48105, United States
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Lucy Waskell
- Department of Anesthesiology, University of Michigan, and VA Medical Center , 2215 Fuller Road, Ann Arbor, Michigan 48105, United States
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41
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Crystal structure of the pristine peroxidase ferryl center and its relevance to proton-coupled electron transfer. Proc Natl Acad Sci U S A 2016; 113:1226-31. [PMID: 26787871 DOI: 10.1073/pnas.1521664113] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The reaction of peroxides with peroxidases oxidizes the heme iron from Fe(III) to Fe(IV)=O and a porphyrin or aromatic side chain to a cationic radical. X-ray-generated hydrated electrons rapidly reduce Fe(IV), thereby requiring very short exposures using many crystals, and, even then, some reduction cannot be avoided. The new generation of X-ray free electron lasers capable of generating intense X-rays on the tenths of femtosecond time scale enables structure determination with no reduction or X-ray damage. Here, we report the 1.5-Å crystal structure of cytochrome c peroxidase (CCP) compound I (CmpI) using data obtained with the Stanford Linear Coherent Light Source (LCLS). This structure is consistent with previous structures. Of particular importance is the active site water structure that can mediate the proton transfer reactions required for both CmpI formation and reduction of Fe(IV)=O to Fe(III)-OH. The structures indicate that a water molecule is ideally positioned to shuttle protons between an iron-linked oxygen and the active site catalytic His. We therefore have carried out both computational and kinetic studies to probe the reduction of Fe(IV)=O. Kinetic solvent isotope experiments show that the transfer of a single proton is critical in the peroxidase rate-limiting step, which is very likely the proton-coupled reduction of Fe(IV)=O to Fe(III)-OH. We also find that the pKa of the catalytic His substantially increases in CmpI, indicating that this active site His is the source of the proton required in the reduction of Fe(IV)=O to Fe(IV)-OH.
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42
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Bougher CJ, Liu S, Hicks SD, Abu-Omar MM. Valence Tautomerization of High-Valent Manganese(V)-Oxo Corrole Induced by Protonation of the Oxo Ligand. J Am Chem Soc 2015; 137:14481-7. [PMID: 26517943 DOI: 10.1021/jacs.5b09759] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The addition of an organic acid to the manganese(V)-oxo corrole complex (tpfc)Mn(V)(O) (tpfc = 5,10,15-tris(pentafluorophenyl)corrole) induces valence tautomerization resulting in the formation of (tpfc(+•))Mn(IV)(OH) in acetonitrile at 298 K. The corrole radical cation manganese(IV) hydroxo complex has been fully characterized by EPR, (1)H NMR, and UV-vis spectroscopy. The reactivity of the valence tautomer (tpfc(+•))Mn(IV)(OH) is compared to that of (tpfc)Mn(V)(O) in three reaction types: hydrogen atom transfer (HAT), electron transfer (ET), and oxygen atom transfer (OAT). (tpfc(+•))Mn(IV)(OH) shows a dramatic 5 orders of magnitude enhancement in the rate of ET but surprisingly does not undergo OAT with PhSMe. The high-valent (tpfc)Mn(V)(O) complex is moderately more reactive toward HAT with substituted phenol and shows superior activity in OAT.
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Affiliation(s)
- Curt J Bougher
- Brown Laboratory, Department of Chemistry, Negishi-Brown Institute for Catalysis (NBIC), Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Shuo Liu
- Brown Laboratory, Department of Chemistry, Negishi-Brown Institute for Catalysis (NBIC), Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Scott D Hicks
- Brown Laboratory, Department of Chemistry, Negishi-Brown Institute for Catalysis (NBIC), Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Mahdi M Abu-Omar
- Brown Laboratory, Department of Chemistry, Negishi-Brown Institute for Catalysis (NBIC), Purdue University , 560 Oval Drive, West Lafayette, Indiana 47907, United States.,School of Chemical Engineering, Purdue University , Forney Hall of Chemical Engineering, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
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43
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Beckwith MA, Ames W, Vila FD, Krewald V, Pantazis DA, Mantel C, Pécaut J, Gennari M, Duboc C, Collomb MN, Yano J, Rehr JJ, Neese F, DeBeer S. How Accurately Can Extended X-ray Absorption Spectra Be Predicted from First Principles? Implications for Modeling the Oxygen-Evolving Complex in Photosystem II. J Am Chem Soc 2015; 137:12815-34. [PMID: 26352328 DOI: 10.1021/jacs.5b00783] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
First principle calculations of extended X-ray absorption fine structure (EXAFS) data have seen widespread use in bioinorganic chemistry, perhaps most notably for modeling the Mn4Ca site in the oxygen evolving complex (OEC) of photosystem II (PSII). The logic implied by the calculations rests on the assumption that it is possible to a priori predict an accurate EXAFS spectrum provided that the underlying geometric structure is correct. The present study investigates the extent to which this is possible using state of the art EXAFS theory. The FEFF program is used to evaluate the ability of a multiple scattering-based approach to directly calculate the EXAFS spectrum of crystallographically defined model complexes. The results of these parameter free predictions are compared with the more traditional approach of fitting FEFF calculated spectra to experimental data. A series of seven crystallographically characterized Mn monomers and dimers is used as a test set. The largest deviations between the FEFF calculated EXAFS spectra and the experimental EXAFS spectra arise from the amplitudes. The amplitude errors result from a combination of errors in calculated S0(2) and Debye-Waller values as well as uncertainties in background subtraction. Additional errors may be attributed to structural parameters, particularly in cases where reliable high-resolution crystal structures are not available. Based on these investigations, the strengths and weaknesses of using first-principle EXAFS calculations as a predictive tool are discussed. We demonstrate that a range of DFT optimized structures of the OEC may all be considered consistent with experimental EXAFS data and that caution must be exercised when using EXAFS data to obtain topological arrangements of complex clusters.
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Affiliation(s)
- Martha A Beckwith
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany.,Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - William Ames
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Fernando D Vila
- Department of Physics, University of Washington , Seattle, Washington 98195, United States
| | - Vera Krewald
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Claire Mantel
- Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France
| | - Jacques Pécaut
- Laboratoire de Reconnaissance Ionique et Chimie de Coordination, Service de Chimie Inorganique et Biologique, (UMR E-3 CEA/UJF, FRE3200 CNRS), CEA-Grenoble, INAC , 17 rue des Martyrs 38054 Grenoble cedex 9, France
| | - Marcello Gennari
- Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France
| | - Carole Duboc
- Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France
| | - Marie-Noëlle Collomb
- Département de Chimie Moléculaire, Université Joseph Fourier Grenoble, CNRS , F-38000 Grenoble, France
| | - Junko Yano
- Physical Biosciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - John J Rehr
- Department of Physics, University of Washington , Seattle, Washington 98195, United States
| | - Frank Neese
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany.,Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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Zhang Y, Biggs JD, Mukamel S. Characterizing the Intermediates Compound I and II in the Cytochrome P450 Catalytic Cycle with Nonlinear X-ray Spectroscopy: A Simulation Study. Chemphyschem 2015; 16:2006-14. [PMID: 25873009 DOI: 10.1002/cphc.201500064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/24/2015] [Indexed: 11/06/2022]
Abstract
Cytochrome P450 enzymes are an important family of biocatalysts that oxidize chemically inert CH bonds. There are many unresolved questions regarding the catalytic reaction intermediates, in particular P450 Compound I (Cpd-I) and II (Cpd-II). By using simple molecular models, we simulate various X-ray spectroscopy signals, including X-ray absorption near-edge structure (XANES), resonant inelastic X-ray scattering (RIXS), and stimulated X-ray Raman spectroscopy (SXRS) of the low- and high-spin states of Cpd-I and II. Characteristic peak patterns are presented and connected to the corresponding electronic structures. These X-ray spectroscopy techniques are complementary to more conventional infrared and optical spectroscopy and they help to elucidate the evolving electronic structures of transient species along the reaction path.
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Affiliation(s)
- Yu Zhang
- Dept. of Chemistry, University of California, 450 Rowland Hall, Irvine, California 92697 (USA).
| | - Jason D Biggs
- Dept. of Chemistry, University of California, 450 Rowland Hall, Irvine, California 92697 (USA)
| | - Shaul Mukamel
- Dept. of Chemistry, University of California, 450 Rowland Hall, Irvine, California 92697 (USA).
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45
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Takayama SIJ, Loutet SA, Mauk AG, Murphy MEP. A Ferric-Peroxo Intermediate in the Oxidation of Heme by IsdI. Biochemistry 2015; 54:2613-21. [PMID: 25853501 DOI: 10.1021/acs.biochem.5b00239] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The canonical heme oxygenases (HOs) catalyze heme oxidation via a heme-bound hydroperoxo intermediate that is stabilized by a water cluster at the active site of the enzyme. In contrast, the hydrophobic active site of IsdI, a heme-degrading enzyme from Staphylococcus aureus, lacks a water cluster and is expected to oxidize heme by an alternative mechanism. Reaction of the IsdI-heme complex with either H2O2 or m-chloroperoxybenzoic acid fails to produce a specific oxidized heme iron intermediate, suggesting that ferric-hydroperoxo or ferryl derivatives of IsdI are not involved in the catalytic mechanism of this enzyme. IsdI lacks a proton-donating group in the distal heme pocket, so the possible involvement of a ferric-peroxo intermediate has been evaluated. Density functional theory (DFT) calculations indicate that heme oxidation involving a ferric-peroxo intermediate is energetically accessible, whereas the energy barrier for a reaction involving a ferric-hydroperoxo intermediate is too great in the absence of a proton donor. We propose that IsdI catalyzes heme oxidation through nucleophilic attack by the heme-bound peroxo species. This proposal is consistent with our previous demonstration by nuclear magnetic resonance spectroscopy that heme ruffling increases the susceptibility of the meso-carbon of heme to nucleophilic attack.
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Affiliation(s)
- Shin-Ichi J Takayama
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Slade A Loutet
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - A Grant Mauk
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael E P Murphy
- †Department of Microbiology and Immunology, ‡Department of Biochemistry and Molecular Biology, and §UBC Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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Smith AT, Pazicni S, Marvin KA, Stevens DJ, Paulsen KM, Burstyn JN. Functional divergence of heme-thiolate proteins: a classification based on spectroscopic attributes. Chem Rev 2015; 115:2532-58. [PMID: 25763468 DOI: 10.1021/cr500056m] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron T Smith
- †Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, Illinois 60208, United States
| | - Samuel Pazicni
- ‡Department of Chemistry, University of New Hampshire, 23 Academic Way, Durham, New Hampshire 03824, United States
| | - Katherine A Marvin
- §Department of Chemistry, Hendrix College, 1600 Washington Avenue, Conway, Arkansas 72032, United States
| | - Daniel J Stevens
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Katherine M Paulsen
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Judith N Burstyn
- ∥Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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47
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Chen Z, Yin G. The reactivity of the active metal oxo and hydroxo intermediates and their implications in oxidations. Chem Soc Rev 2015; 44:1083-100. [DOI: 10.1039/c4cs00244j] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The relationships of active metal oxo and hydroxo moieties have been summarized with their implications for biological and chemical oxidations.
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Affiliation(s)
- Zhuqi Chen
- Key Laboratory for Large-Format Battery Materials and System
- Ministry of Education
- School of Chemistry and Chemical Engineering
- Huazhong University of Science and Technology
- Wuhan 430074
| | - Guochuan Yin
- Key Laboratory for Large-Format Battery Materials and System
- Ministry of Education
- School of Chemistry and Chemical Engineering
- Huazhong University of Science and Technology
- Wuhan 430074
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48
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Surducan M, Makarov SV, Silaghi-Dumitrescu R. O-S Bond Activation in Structures Isoelectronic with Ferric Peroxide Species Known in O-O-Activating Enzymes: Relevance for Sulfide Activation and Sulfite Reductases. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402657] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Casadei CM, Gumiero A, Metcalfe CL, Murphy EJ, Basran J, Concilio MG, Teixeira SCM, Schrader TE, Fielding AJ, Ostermann A, Blakeley MP, Raven EL, Moody PCE. Heme enzymes. Neutron cryo-crystallography captures the protonation state of ferryl heme in a peroxidase. Science 2014; 345:193-7. [PMID: 25013070 DOI: 10.1126/science.1254398] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Heme enzymes activate oxygen through formation of transient iron-oxo (ferryl) intermediates of the heme iron. A long-standing question has been the nature of the iron-oxygen bond and, in particular, the protonation state. We present neutron structures of the ferric derivative of cytochrome c peroxidase and its ferryl intermediate; these allow direct visualization of protonation states. We demonstrate that the ferryl heme is an Fe(IV)=O species and is not protonated. Comparison of the structures shows that the distal histidine becomes protonated on formation of the ferryl intermediate, which has implications for the understanding of O-O bond cleavage in heme enzymes. The structures highlight the advantages of neutron cryo-crystallography in probing reaction mechanisms and visualizing protonation states in enzyme intermediates.
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Affiliation(s)
- Cecilia M Casadei
- Department of Biochemistry and Henry Wellcome Laboratories for Structural Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK. Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Andrea Gumiero
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Clive L Metcalfe
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Emma J Murphy
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Jaswir Basran
- Department of Biochemistry and Henry Wellcome Laboratories for Structural Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | | | - Susana C M Teixeira
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France. EPSAM, Keele University, Keele, Staffordshire ST5 5BG, UK
| | - Tobias E Schrader
- Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching, Germany
| | - Alistair J Fielding
- The Photon Science Institute, The University of Manchester, Manchester M13 9PL, UK
| | - Andreas Ostermann
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstraße 1, D-85748 Garching, Germany
| | | | - Emma L Raven
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK.
| | - Peter C E Moody
- Department of Biochemistry and Henry Wellcome Laboratories for Structural Biology, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
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50
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Yosca TH, Behan RK, Krest CM, Onderko EL, Langston MC, Green MT. Setting an upper limit on the myoglobin iron(IV)hydroxide pK(a): insight into axial ligand tuning in heme protein catalysis. J Am Chem Soc 2014; 136:9124-31. [PMID: 24875119 PMCID: PMC4091272 DOI: 10.1021/ja503588n] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To provide insight into the iron(IV)hydroxide pK(a) of histidine ligated heme proteins, we have probed the active site of myoglobin compound II over the pH range of 3.9-9.5, using EXAFS, Mössbauer, and resonance Raman spectroscopies. We find no indication of ferryl protonation over this pH range, allowing us to set an upper limit of 2.7 on the iron(IV)hydroxide pK(a) in myoglobin. Together with the recent determination of an iron(IV)hydroxide pK(a) ∼ 12 in the thiolate-ligated heme enzyme cytochrome P450, this result provides insight into Nature's ability to tune catalytic function through its choice of axial ligand.
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Affiliation(s)
- Timothy H Yosca
- Department of Chemistry, Pennsylvania State University , University Park, State College, Pennsylvania 16802, United States
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