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Thomas J, Mokkawes T, Senft L, Dey A, Gordon JB, Ivanovic-Burmazovic I, de Visser SP, Goldberg DP. Axial Ligation Impedes Proton-Coupled Electron-Transfer Reactivity of a Synthetic Compound-I Analogue. J Am Chem Soc 2024; 146:12338-12354. [PMID: 38669456 DOI: 10.1021/jacs.3c08950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
The nature of the axial ligand in high-valent iron-oxo heme enzyme intermediates and related synthetic catalysts is a critical structural element for controlling proton-coupled electron-transfer (PCET) reactivity of these species. Herein, we describe the generation and characterization of three new 6-coordinate, iron(IV)-oxo porphyrinoid-π-cation-radical complexes and report their PCET reactivity together with a previously published 5-coordinate analogue, FeIV(O)(TBP8Cz+•) (TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato3-) (2) (Cho, K. A high-valent iron-oxo corrolazine activates C-H bonds via hydrogen-atom transfer. J. Am. Chem. Soc. 2012, 134, 7392-7399). The new complexes FeIV(O)(TBP8Cz+•)(L) (L = 1-methyl imidazole (1-MeIm) (4a), 4-dimethylaminopyridine (DMAP) (4b), cyanide (CN-)(4c)) can be generated from either oxidation of the ferric precursors or by addition of L to the Compound-I (Cpd-I) analogue at low temperatures. These complexes were characterized by UV-vis, electron paramagnetic resonance (EPR), and Mössbauer spectroscopies, and cryospray ionization mass spectrometry (CSI-MS). Kinetic studies using 4-OMe-TEMPOH as a test substrate indicate that coordination of a sixth axial ligand dramatically lowers the PCET reactivity of the Cpd-I analogue (rates up to 7000 times slower). Extensive density functional theory (DFT) calculations together with the experimental data show that the trend in reactivity with the axial ligands does not correlate with the thermodynamic driving force for these reactions or the calculated strengths of the O-H bonds being formed in the FeIV(O-H) products, pointing to non-Bell-Evans-Polanyi behavior. However, the PCET reactivity does follow a trend with the bracketed reduction potential of Cpd-I analogues and calculated electron affinities. The combined data suggest a concerted mechanism (a concerted proton electron transfer (CPET)) and an asynchronous movement of the electron/proton pair in the transition state.
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Affiliation(s)
- Jithin Thomas
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Thirakorn Mokkawes
- The Manchester Institute of Biotechnology and Department of Chemical Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Laura Senft
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr., 5-13, Haus D, 81377 München, Germany
| | - Aniruddha Dey
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Jesse B Gordon
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Ivana Ivanovic-Burmazovic
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr., 5-13, Haus D, 81377 München, Germany
| | - Sam P de Visser
- The Manchester Institute of Biotechnology and Department of Chemical Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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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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Hubbard CD, Chatterjee D, Oszajca M, Polaczek J, Impert O, Chrzanowska M, Katafias A, Puchta R, van Eldik R. Inorganic reaction mechanisms. A personal journey. Dalton Trans 2020; 49:4599-4659. [PMID: 32162632 DOI: 10.1039/c9dt04620h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This review covers highlights of the work performed in the van Eldik group on inorganic reaction mechanisms over the past two decades in the form of a personal journey. Topics that are covered include, from NO to HNO chemistry, peroxide activation in model porphyrin and enzymatic systems, the wonder-world of RuIII(edta) chemistry, redox chemistry of Ru(iii) complexes, Ru(ii) polypyridyl complexes and their application, relevant physicochemical properties and reaction mechanisms in ionic liquids, and mechanistic insight from computational chemistry. In each of these sections, typical examples of mechanistic studies are presented in reference to related work reported in the literature.
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Affiliation(s)
- Colin D Hubbard
- Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstr. 1, 91058 Erlangen, Germany.
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Baglia RA, Zaragoza JPT, Goldberg DP. Biomimetic Reactivity of Oxygen-Derived Manganese and Iron Porphyrinoid Complexes. Chem Rev 2017; 117:13320-13352. [PMID: 28991451 PMCID: PMC6058703 DOI: 10.1021/acs.chemrev.7b00180] [Citation(s) in RCA: 204] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Heme proteins utilize the heme cofactor, an iron porphyrin, to perform a diverse range of reactions including dioxygen binding and transport, electron transfer, and oxidation/oxygenations. These reactions share several key metalloporphyrin intermediates, typically derived from dioxygen and its congeners such as hydrogen peroxide. These species are composed of metal-dioxygen, metal-superoxo, metal-peroxo, and metal-oxo adducts. A wide variety of synthetic metalloporphyrinoid complexes have been synthesized to generate and stabilize these intermediates. These complexes have been studied to determine the spectroscopic features, structures, and reactivities of such species in controlled and well-defined environments. In this Review, we summarize recent findings on the reactivity of these species with common porphyrinoid scaffolds employed for biomimetic studies. The proposed mechanisms of action are emphasized. This Review is organized by structural type of metal-oxygen intermediate and broken into subsections based on the metal (manganese and iron) and porphyrinoid ligand (porphyrin, corrole, and corrolazine).
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Affiliation(s)
- Regina A. Baglia
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Jan Paulo T. Zaragoza
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, 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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Oszajca M, Franke A, Brindell M, Stochel G, van Eldik R. Redox cycling in the activation of peroxides by iron porphyrin and manganese complexes. ‘Catching’ catalytic active intermediates. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.01.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Sainna MA, Kumar S, Kumar D, Fornarini S, Crestoni ME, de Visser SP. A comprehensive test set of epoxidation rate constants for iron(iv)-oxo porphyrin cation radical complexes. Chem Sci 2014; 6:1516-1529. [PMID: 29560240 PMCID: PMC5811088 DOI: 10.1039/c4sc02717e] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/08/2014] [Indexed: 12/31/2022] Open
Abstract
Trends in oxygen atom transfer to Compound I of the P450 models with an extensive test set have been studied and show a preferred regioselectivity of epoxidation over hydroxylation in the gas-phase for the first time.
Cytochrome P450 enzymes are heme based monoxygenases that catalyse a range of oxygen atom transfer reactions with various substrates, including aliphatic and aromatic hydroxylation as well as epoxidation reactions. The active species is short-lived and difficult to trap and characterize experimentally, moreover, it reacts in a regioselective manner with substrates leading to aliphatic hydroxylation and epoxidation products, but the origin of this regioselectivity is poorly understood. We have synthesized a model complex and studied it with low-pressure Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry (MS). A novel approach was devised using the reaction of [FeIII(TPFPP)]+ (TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion) with iodosylbenzene as a terminal oxidant which leads to the production of ions corresponding to [FeIV(O)(TPFPP+˙)]+. This species was isolated in the gas-phase and studied in its reactivity with a variety of olefins. Product patterns and rate constants under Ideal Gas conditions were determined by FT-ICR MS. All substrates react with [FeIV(O)(TPFPP+˙)]+ by a more or less efficient oxygen atom transfer process. In addition, substrates with low ionization energies react by a charge-transfer channel, which enabled us to determine the electron affinity of [FeIV(O)(TPFPP+˙)]+ for the first time. Interestingly, no hydrogen atom abstraction pathways are observed for the reaction of [FeIV(O)(TPFPP+˙)]+ with prototypical olefins such as propene, cyclohexene and cyclohexadiene and also no kinetic isotope effect in the reaction rate is found, which suggests that the competition between epoxidation and hydroxylation – in the gas-phase – is in favour of substrate epoxidation. This notion further implies that P450 enzymes will need to adapt their substrate binding pocket, in order to enable favourable aliphatic hydroxylation over double bond epoxidation pathways. The MS studies yield a large test-set of experimental reaction rates of iron(iv)–oxo porphyrin cation radical complexes, so far unprecedented in the gas-phase, providing a benchmark for calibration studies using computational techniques. Preliminary computational results presented here confirm the observed trends excellently and rationalize the reactivities within the framework of thermochemical considerations and valence bond schemes.
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Affiliation(s)
- Mala A Sainna
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science , The University of Manchester , 131 Princess Street , Manchester M1 7DN , UK .
| | - Suresh Kumar
- Department of Applied Physics , School for Physical Sciences , Babasaheb Bhimrao Ambedkar University , Vidya Vihar, Rai Bareilly Road , Lucknow 226 025 , India .
| | - Devesh Kumar
- Department of Applied Physics , School for Physical Sciences , Babasaheb Bhimrao Ambedkar University , Vidya Vihar, Rai Bareilly Road , Lucknow 226 025 , India .
| | - Simonetta Fornarini
- Dipartimento di Chimica e Tecnologie del Farmaco , Università di Roma "La Sapienza" , P.le A. Moro 5 , 00185 , Roma , Italy . ;
| | - Maria Elisa Crestoni
- Dipartimento di Chimica e Tecnologie del Farmaco , Università di Roma "La Sapienza" , P.le A. Moro 5 , 00185 , Roma , Italy . ;
| | - Sam P de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science , The University of Manchester , 131 Princess Street , Manchester M1 7DN , UK .
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Ji L, Franke A, Brindell M, Oszajca M, Zahl A, van Eldik R. Combined experimental and theoretical study on the reactivity of compounds I and II in horseradish peroxidase biomimetics. Chemistry 2014; 20:14437-50. [PMID: 25220399 DOI: 10.1002/chem.201402347] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Indexed: 12/21/2022]
Abstract
For the exploration of the intrinsic reactivity of two key active species in the catalytic cycle of horseradish peroxidase (HRP), Compound I (HRP-I) and Compound II (HRP-II), we generated in situ [Fe(IV) O(TMP(+.) )(2-MeIm)](+) and [Fe(IV) O(TMP)(2-MeIm)](0) (TMP=5,10,15,20-tetramesitylporphyrin; 2-MeIm=2-methylimidazole) as biomimetics for HRP-I and HRP-II, respectively. Their catalytic activities in epoxidation, hydrogen abstraction, and heteroatom oxidation reactions were studied in acetonitrile at -15 °C by utilizing rapid-scan UV/Vis spectroscopy. Comparison of the second-order rate constants measured for the direct reactions of the HRP-I and HRP-II mimics with the selected substrates clearly confirmed the outstanding oxidizing capability of the HRP-I mimic, which is significantly higher than that of HRP-II. The experimental study was supported by computational modeling (DFT calculations) of the oxidation mechanism of the selected substrates with the involvement of quartet and doublet HRP-I mimics ((2,4) Cpd I) and the closed-shell triplet spin HRP-II model ((3) Cpd II) as oxidizing species. The significantly lower activation barriers calculated for the oxidation systems involving (2,4) Cpd I than those found for (3) Cpd II are in line with the much higher oxidizing efficiency of the HRP-I mimic proven in the experimental part of the study. In addition, the DFT calculations show that all three reaction types catalyzed by HRP-I occur on the doublet spin surface in an effectively concerted manner, whereas these reactions may proceed in a stepwise mechanism with the HRP-II mimic as oxidant. However, the high desaturation or oxygen rebound barriers during CH bond activation processes by the HRP-II mimic predict a sufficient lifetime for the substrate radical formed through hydrogen abstraction. Thus, the theoretical calculations suggest that the dissociation of the substrate radical may be a more favorable pathway than desaturation or oxygen rebound processes. Importantly, depending on the electronic nature of the oxidizing species, that is, (2,4) Cpd I or (3) Cpd II, an interesting region-selective conversion phenomenon between sulfoxidation and H-atom abstraction was revealed in the course of the oxidation reaction of dimethylsulfide. The combined experimental and theoretical study on the elucidation of the intrinsic reactivity patterns of the HRP-I and HRP-II mimics provides a valuable tool for evaluating the particular role of the HRP active species in biological systems.
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Affiliation(s)
- Li Ji
- Inorganic Chemistry, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen (Germany); College of Environmental and Resource Sciences, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058 (China)
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Kumar D, Latifi R, Kumar S, Rybak-Akimova EV, Sainna MA, de Visser SP. Rationalization of the Barrier Height for p-Z-styrene Epoxidation by Iron(IV)-Oxo Porphyrin Cation Radicals with Variable Axial Ligands. Inorg Chem 2013; 52:7968-79. [DOI: 10.1021/ic4005104] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Devesh Kumar
- Department of Applied Physics, School of Physical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar,
Rae Bareilly Road, Lucknow 226-025, India
| | - Reza Latifi
- Manchester Institute of Biotechnology and School
of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7DN,
U.K
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United
States
| | - Suresh Kumar
- Department of Applied Physics, School of Physical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar,
Rae Bareilly Road, Lucknow 226-025, India
| | | | - Mala A. Sainna
- Manchester Institute of Biotechnology and School
of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7DN,
U.K
| | - Sam P. de Visser
- Manchester Institute of Biotechnology and School
of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7DN,
U.K
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Cho K, Leeladee P, McGown AJ, DeBeer S, Goldberg DP. A high-valent iron-oxo corrolazine activates C-H bonds via hydrogen-atom transfer. J Am Chem Soc 2012; 134:7392-9. [PMID: 22489757 DOI: 10.1021/ja3018658] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxidation of the Fe(III) complex (TBP(8)Cz)Fe(III) [TBP(8)Cz = octakis(4-tert-butylphenyl)corrolazinate] with O-atom transfer oxidants under a variety of conditions gives the reactive high-valent Fe(O) complex (TBP(8)Cz(+•))Fe(IV)(O) (2). The solution state structure of 2 was characterized by XAS [d(Fe-O) = 1.64 Å]. This complex is competent to oxidize a range of C-H substrates. Product analyses and kinetic data show that these reactions occur via rate-determining hydrogen-atom transfer (HAT), with a linear correlation for log k versus BDE(C-H), and the following activation parameters for xanthene (Xn) substrate: ΔH(++) = 12.7 ± 0.8 kcal mol(-1), ΔS(++) = -9 ± 3 cal K(-1) mol(-1), and KIE = 5.7. Rebound hydroxylation versus radical dimerization for Xn is favored by lowering the reaction temperature. These findings provide insights into the factors that control the intrinsic reactivity of Compound I heme analogues.
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Affiliation(s)
- Kevin Cho
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
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McDonald AR, Bukowski MR, Farquhar ER, Jackson TA, Koehntop KD, Seo MS, De Hont RF, Stubna A, Halfen JA, Münck E, Nam W, Que L. Sulfur versus iron oxidation in an iron-thiolate model complex. J Am Chem Soc 2010; 132:17118-29. [PMID: 21070030 DOI: 10.1021/ja1045428] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the absence of base, the reaction of [Fe(II)(TMCS)]PF6 (1, TMCS = 1-(2-mercaptoethyl)-4,8,11-trimethyl-1,4,8,11-tetraazacyclotetradecane) with peracid in methanol at -20 °C did not yield the oxoiron(IV) complex (2, [Fe(IV)(O)(TMCS)]PF6), as previously observed in the presence of strong base (KO(t)Bu). Instead, the addition of 1 equiv of peracid resulted in 50% consumption of 1. The addition of a second equivalent of peracid resulted in the complete consumption of 1 and the formation of a new species 3, as monitored by UV-vis, ESI-MS, and Mössbauer spectroscopies. ESI-MS showed 3 to be formulated as [Fe(II)(TMCS) + 2O](+), while EXAFS analysis suggested that 3 was an O-bound iron(II)-sulfinate complex (Fe-O = 1.95 Å, Fe-S = 3.26 Å). The addition of a third equivalent of peracid resulted in the formation of yet another compound, 4, which showed electronic absorption properties typical of an oxoiron(IV) species. Mössbauer spectroscopy confirmed 4 to be a novel iron(IV) compound, different from 2, and EXAFS (Fe═O = 1.64 Å) and resonance Raman (ν(Fe═O) = 831 cm(-1)) showed that indeed an oxoiron(IV) unit had been generated in 4. Furthermore, both infrared and Raman spectroscopy gave indications that 4 contains a metal-bound sulfinate moiety (ν(s)(SO2) ≈ 1000 cm (-1), ν(as)(SO2) ≈ 1150 cm (-1)). Investigations into the reactivity of 1 and 2 toward H(+) and oxygen atom transfer reagents have led to a mechanism for sulfur oxidation in which 2 could form even in the absence of base but is rapidly protonated to yield an oxoiron(IV) species with an uncoordinated thiol moiety that acts as both oxidant and substrate in the conversion of 2 to 3.
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Affiliation(s)
- Aidan R McDonald
- Department of Chemistry and Center for Metals in Biocatalysis, 207 Pleasant Street SE, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Kumar D, Karamzadeh B, Sastry GN, de Visser SP. What factors influence the rate constant of substrate epoxidation by compound I of cytochrome P450 and analogous iron(IV)-oxo oxidants? J Am Chem Soc 2010; 132:7656-67. [PMID: 20481499 DOI: 10.1021/ja9106176] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cytochromes P450 are a versatile range of mono-oxygenase enzymes that catalyze a variety of different chemical reactions, of which the key reactions include aliphatic hydroxylation and C=C double bond epoxidation. To establish the fundamental factors that govern substrate epoxidation by these enzymes we have done a systematic density functional theory study on substrate epoxidation by the active species of P450 enzymes, namely the iron(IV)-oxo porphyrin cation radical oxidant or Compound I. We show here, for the first time, that the rate constant of substrate epoxidation, and hence the activation energy, correlates with the ionization potential of the substrate as well as with intrinsic electronic properties of the active oxidant such as the polarizability volume. To explain these findings we present an electron-transfer model for the reaction mechanism that explains the factors that determine the barrier heights and developed a valence bond (VB) curve crossing mechanism to rationalize the observed trends. In addition, we have found a correlation for substrate epoxidation reactions catalyzed by a range of heme and nonheme iron(IV)-oxo oxidants with the strength of the O-H bond in the iron-hydroxo complex, i.e. BDE(OH), which is supported by the VB model. Finally, the fundamental factors that determine the regioselectivity change between substrate hydroxylation and epoxidation are discussed. It is shown that the regioselectivity of aliphatic hydroxylation versus double bond epoxidation is not influenced by the choice of the oxidant but is purely substrate dependent.
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Affiliation(s)
- Devesh Kumar
- Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India.
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