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Zhu L, Zhou J, Zhang Q, Li Y, Wang W. Computational study on the metabolic activation mechanism of PeCDD by Cytochrome P450 1A1. JOURNAL OF HAZARDOUS MATERIALS 2021; 405:124276. [PMID: 33158646 DOI: 10.1016/j.jhazmat.2020.124276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/30/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Cytochrome P450 enzymes (CYPs) are crucial for metabolizing dioxin compounds such as 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD). Here we have applied molecular dynamic simulations (MD), quantum mechanics/molecular mechanics methods (QM/MM) and density functional theory (DFT) to investigate the metabolic activation and transformation of PeCDD catalyzed by CYP1A1. Our QM/MM calculations highlight that PeCDD can be activated by P450s through the well-known electrophilic addition mechanism with an average energy barrier of 20.9 kcal/mol. Based on the results of previous experimental studies, further conversions of ketone products and epoxidation products that are mediated by P450 enzymes were investigated through DFT calculations. Analysis of the structures via the noncovalent interactions (NCI) method and the distortion-interaction model suggests that amino acids Ser122, Ala317, Ile386 and Leu496 play important roles in the metabolic process.
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Affiliation(s)
- Ledong Zhu
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Jie Zhou
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China.
| | - Yanwei Li
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
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Reis AC, Čvančarová M, Liu Y, Lenz M, Hettich T, Kolvenbach BA, Corvini PFX, Nunes OC. Biodegradation of sulfamethoxazole by a bacterial consortium of Achromobacter denitrificans PR1 and Leucobacter sp. GP. Appl Microbiol Biotechnol 2018; 102:10299-10314. [PMID: 30294753 DOI: 10.1007/s00253-018-9411-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 11/26/2022]
Abstract
In the last decade, biological degradation and mineralization of antibiotics have been increasingly reported feats of environmental bacteria. The most extensively described example is that of sulfonamides that can be degraded by several members of Actinobacteria and Proteobacteria. Previously, we reported sulfamethoxazole (SMX) degradation and partial mineralization by Achromobacter denitrificans strain PR1, isolated from activated sludge. However, further studies revealed an apparent instability of this metabolic trait in this strain. Here, we investigated this instability and describe the finding of a low-abundance and slow-growing actinobacterium, thriving only in co-culture with strain PR1. This organism, named GP, shared highest 16S rRNA gene sequence similarity (94.6-96.9%) with the type strains of validly described species of the genus Leucobacter. This microbial consortium was found to harbor a homolog to the sulfonamide monooxygenase gene (sadA) also found in other sulfonamide-degrading bacteria. This gene is overexpressed in the presence of the antibiotic, and evidence suggests that it codes for a group D flavin monooxygenase responsible for the ipso-hydroxylation of SMX. Additional side reactions were also detected comprising an NIH shift and a Baeyer-Villiger rearrangement, which indicate an inefficient biological transformation of these antibiotics in the environment. This work contributes to further our knowledge in the degradation of this ubiquitous micropollutant by environmental bacteria.
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Affiliation(s)
- Ana C Reis
- LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, Department of Chemical Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal
- Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Monika Čvančarová
- Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Ying Liu
- Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Markus Lenz
- Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Timm Hettich
- Institute for Chemistry and Bioanalytics, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Boris A Kolvenbach
- Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Philippe F-X Corvini
- Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Hofackerstrasse 30, 4132, Muttenz, Switzerland
| | - Olga C Nunes
- LEPABE-Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, Department of Chemical Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
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Li XX, Wang Y, Zheng QC, Zhang HX. Detoxification of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by cytochrome P450 enzymes: A theoretical investigation. J Inorg Biochem 2015; 154:21-8. [PMID: 26544505 DOI: 10.1016/j.jinorgbio.2015.10.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 10/12/2015] [Accepted: 10/19/2015] [Indexed: 11/24/2022]
Abstract
Two types of detoxification routes, N-demethylation to form 4-phenyl-1,2,3,6-tetrahydropyridine (PTP) and aromatic hydroxylation to generate 4-(4'-hydroxyphenyl)-1-methyl-1,2,3,6-tetrahydropyridine (MPTP-OH), for 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mediated by Compound I (Cpd I) of cytochrome P450 are investigated theoretically using hybrid density functional calculations. Quantum chemical results reveal that for the N-demethylation, the initial C-H bond activation is achieved via a hydrogen atom transfer (HAT) mechanism. This is followed by a subsequent O-rebound to yield the carbinolamine intermediate. Due to the nature of pericyclic reaction, the generated carbinolamine decomposes in a non-enzymatic aqueous environment with the assistance of water molecules, forming amine and hydrated formaldehyde. For the aromatic hydroxylation, an initial addition of Cpd I to the substrate occurs mainly through a side-on approach with a subsequent proton shuttle to form the phenol product. A comparison of the energy barriers for both routes indicates that the N-demethylation (7.5/5.7kcal/mol for the quartet/doublet state in solvent) is thermodynamically more favorable than the aromatic hydroxylation process (14.9/14.8kcal/mol for the quartet/doublet state in solvent). This trend is in good agreement with the experimental product distribution, viz., the N-demethylation product PTP is more than the aromatic hydroxylation product MPTP-OH. Taken together, these observations not only enrich our knowledge on the mechanistic details of the N-dealkylation and the aromatic hydroxylation by P450s, but also provide certain insights into the metabolism of other analogous toxins.
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Affiliation(s)
- Xiao-Xi Li
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China; State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China
| | - Yong Wang
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
| | - Qing-Chuan Zheng
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University, Changchun 130023, People's Republic of China; State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.
| | - Hong-Xing Zhang
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China
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4
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Shaik S, Milko P, Schyman P, Usharani D, Chen H. Trends in Aromatic Oxidation Reactions Catalyzed by Cytochrome P450 Enzymes: A Valence Bond Modeling. J Chem Theory Comput 2011; 7:327-39. [DOI: 10.1021/ct100554g] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Sason Shaik
- The Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Petr Milko
- The Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Patric Schyman
- The Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Dandamudi Usharani
- The Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Hui Chen
- The Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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Shaik S, Cohen S, Wang Y, Chen H, Kumar D, Thiel W. P450 Enzymes: Their Structure, Reactivity, and Selectivity—Modeled by QM/MM Calculations. Chem Rev 2009; 110:949-1017. [DOI: 10.1021/cr900121s] [Citation(s) in RCA: 791] [Impact Index Per Article: 52.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sason Shaik
- Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Shimrit Cohen
- Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Yong Wang
- Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Hui Chen
- Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Devesh Kumar
- Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Walter Thiel
- Institute of Chemistry and the Lise-Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel, and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
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Bathelt CM, Mulholland AJ, Harvey JN. QM/MM Modeling of Benzene Hydroxylation in Human Cytochrome P450 2C9. J Phys Chem A 2008; 112:13149-56. [DOI: 10.1021/jp8016908] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christine M. Bathelt
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Cantocks’ Close, Bristol BS8 1TS, U.K
| | - Adrian J. Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Cantocks’ Close, Bristol BS8 1TS, U.K
| | - Jeremy N. Harvey
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Cantocks’ Close, Bristol BS8 1TS, U.K
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7
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Borowski T, Bassan A, Siegbahn PEM. 4-Hydroxyphenylpyruvate Dioxygenase: A Hybrid Density Functional Study of the Catalytic Reaction Mechanism. Biochemistry 2004; 43:12331-42. [PMID: 15379572 DOI: 10.1021/bi049503y] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Density functional calculations using the B3LYP functional has been used to study the reaction mechanism of 4-hydroxyphenylpyruvate dioxygenase. The first part of the catalytic reaction, dioxygen activation, is found to have the same mechanism as in alpha-ketoglutarate-dependent enzymes; the ternary enzyme-substrate-dioxygen complex is first decarboxylated to the iron(II)-peracid intermediate, followed by heterolytic cleavage of the O-O bond yielding an iron(IV)-oxo species. This highly reactive intermediate attacks the aromatic ring at the C1 position and forms a radical sigma complex, which can either form an arene oxide or undergo a C1-C2 side-chain migration. The arene oxide is found to have no catalytic relevance. The side-chain migration is a two-step process; the carbon-carbon bond cleavage first affords a biradical intermediate, followed by a decay of this species forming the new C-C bond. The ketone intermediate formed by a 1,2 shift of an acetic acid group rearomatizes either at the active site of the enzyme or in solution. The hypothetical oxidation of the aromatic ring at the C2 position was also studied to shed light on the 4-HPPD product specificity. In addition, the benzylic hydroxylation reaction, catalyzed by 4-hydroxymandelate synthase, was also studied. The results are in good agreement with the experimental findings.
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Affiliation(s)
- Tomasz Borowski
- Department of Physics, Stockholm Center for Physics, Astronomy, and Biotechnology, Stockholm University, S-106 91, Stockholm, Sweden.
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Bathelt CM, Ridder L, Mulholland AJ, Harvey JN. Mechanism and structure–reactivity relationships for aromatic hydroxylation by cytochrome P450. Org Biomol Chem 2004; 2:2998-3005. [PMID: 15480465 DOI: 10.1039/b410729b] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytochrome P450 enzymes play a central role in drug metabolism, and models of their mechanism could contribute significantly to pharmaceutical research and development of new drugs. The mechanism of cytochrome P450 mediated hydroxylation of aromatics and the effects of substituents on reactivity have been investigated using B3LYP density functional theory computations in a realistic porphyrin model system. Two different orientations of substrate approach for addition of Compound I to benzene, and also possible subsequent rearrangement pathways have been explored. The rate-limiting Compound I addition to an aromatic carbon atom proceeds on the doublet potential energy surface via a transition state with mixed radical and cationic character. Subsequent formation of epoxide, ketone and phenol products is shown to occur with low barriers, especially starting from a cation-like rather than a radical-like tetrahedral adduct of Compound I with benzene. Effects of ring substituents were explored by calculating the activation barriers for Compound I addition in the meta and para-position for a range of monosubstituted benzenes and for more complex polysubstituted benzenes. Two structure-reactivity relationships including 8 and 10 different substituted benzenes have been determined using (i) experimentally derived Hammett sigma-constants and (ii) a theoretical scale based on bond dissociation energies of hydroxyl adducts of the substrates, respectively. In both cases a dual-parameter approach that employs a combination of radical and cationic electronic descriptors gave good relationships with correlation coefficients R2 of 0.96 and 0.82, respectively. These relationships can be extended to predict the reactivity of other substituted aromatics, and thus can potentially be used in predictive drug metabolism models.
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Affiliation(s)
- Christine M Bathelt
- School of Chemistry and Centre for Computational Chemistry, University of Bristol, UK
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Bathelt CM, Ridder L, Mulholland AJ, Harvey JN. Aromatic Hydroxylation by Cytochrome P450: Model Calculations of Mechanism and Substituent Effects. J Am Chem Soc 2003; 125:15004-5. [PMID: 14653732 DOI: 10.1021/ja035590q] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism and selectivity of aromatic hydroxylation by cytochrome P450 enzymes is explored using new B3LYP density functional theory computations. The calculations, using a realistic porphyrin model system, show that rate-determining addition of compound I to an aromatic carbon atom proceeds via a transition state with partial radical and cationic character. Reactivity is shown to depend strongly on ring substituents, with both electron-withdrawing and -donating groups strongly decreasing the addition barrier in the para position, and it is shown that the calculated barrier heights can be reproduced by a new dual-parameter equation based on radical and cationic Hammett sigma parameters.
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Affiliation(s)
- Christine M Bathelt
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
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de Visser SP, Shaik S. A proton-shuttle mechanism mediated by the porphyrin in benzene hydroxylation by cytochrome p450 enzymes. J Am Chem Soc 2003; 125:7413-24. [PMID: 12797816 DOI: 10.1021/ja034142f] [Citation(s) in RCA: 273] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Benzene hydroxylation is a fundamental process in chemical catalysis. In nature, this reaction is catalyzed by the enzyme cytochrome P450 via oxygen transfer in a still debated mechanism of considerable complexity. The paper uses hybrid density functional calculations to elucidate the mechanisms by which benzene is converted to phenol, benzene oxide, and ketone, by the active species of the enzyme, the high-valent iron-oxo porphyrin species. The effects of the protein polarity and hydrogen-bonding donation to the active species are mimicked, as before (Ogliaro, F.; Cohen, S.; de Visser, S. P.; Shaik, S. J. Am. Chem. Soc. 2000, 122, 12892-12893). It is verified that the reaction does not proceed either by hydrogen abstraction or by initial electron transfer (Ortiz de Montellano, P. R. In Cytochrome P450: Structure, Mechanism and Biochemistry, 2nd ed.; Ortiz de Montellano, P. R., Ed.; Plenum Press: New York, 1995; Chapter 8, pp 245-303). In accord with the latest experimental conclusions, the theoretical calculations show that the reactivity is an interplay of electrophilic and radicalar pathways, which involve an initial attack on the pi-system of the benzene to produce sigma-complexes (Korzekwa, K. R.; Swinney, D. C.; Trager, W. T. Biochemistry 1989, 28, 9019-9027). The dominant reaction channel is electrophilic and proceeds via the cationic sigma-complex,( 2)3, that involves an internal ion pair made from a cationic benzene moiety and an anionic iron porphyrin. The minor channel proceeds by intermediacy of the radical sigma-complex, (2)2, in which the benzene moiety is radicalar and the iron-porphyrin moiety is neutral. Ring closure in these intermediates produces the benzene oxide product ((2)4), which does not rearrange to phenol ((2)7) or cyclohexenone ((2)6). While such a rearrangement can occur post-enzymatically under physiological conditions by acid catalysis, the computations reveal a novel mechanism whereby the active species of the enzyme catalyzes directly the production of phenol and cyclohexenone. This enzymatic mechanism involves proton shuttles mediated by the porphyrin ring through the N-protonated intermediate, (2)5, which relays the proton either to the oxygen atom to form phenol ((2)7) or to the ortho-carbon atom to produce cyclohexenone product ((2)6). The formation of the phenol via this proton-shuttle mechanism will be competitive with the nonenzymatic conversion of benzene oxide to phenol by external acid catalysis. With the assumption that (2)5 is not fully thermalized, this novel mechanism would account also for the observation that there is a partial skeletal retention of the original hydrogen of the activated C-H bond, due to migration of the hydrogen from the site of hydroxylation to the adjacent carbon (so-called "NIH shift" (Jerina, D. M.; Daly, J. W. Science 1974, 185, 573-582)). Thus, in general, the computationally discovered mechanism of a porphyrin proton shuttle suggests thatthere is an enzymatic pathway that converts benzene directly to a phenol and ketone, in addition to nonenzymatic production of these species by conversion of arene oxide to phenol and ketone. The potential generality of protonated porphyrin intermediates in P450 chemistry is discussed in the light of the H/D exchange observed during some olefin epoxidation reactions (Groves, J. T.; Avaria-Neisser, G. E.; Fish, K. M.; Imachi, M.; Kuczkowski, R. J. Am. Chem. Soc. 1986, 108, 3837-3838) and the general observation of heme alkylation products (Kunze, K. L.; Mangold, B. L. K.; Wheeler, C.; Beilan, H. S.; Ortiz de Montellano, P. R. J. Biol. Chem. 1983, 258, 4202-4207). The competition, similarities, and differences between benzene oxidation viz. olefin epoxidation and alkanyl C-H hydroxylation are discussed, and comparison is made with relevant experimental and computational data. The dominance of low-spin reactivity in benzene hydroxylation viz. two-state reactivity (Shaik, S.; de Visser, S. P.; Ogliaro, F.; Schwarz, H.; Schröder, D. Curr. Opin. Chem. Biol. 2002, 6, 556-567) in olefin epoxidation and alkane hydroxylation is traced to the loss of benzene resonance energy during the bond activation step.
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Affiliation(s)
- Sam P de Visser
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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Veeger C. Does P450-type catalysis proceed through a peroxo-iron intermediate? A review of studies with microperoxidase. J Inorg Biochem 2002; 91:35-45. [PMID: 12121760 DOI: 10.1016/s0162-0134(02)00393-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Recent stopped-flow kinetics demonstrated the existence of an intermediate before the occurrence of the final product of the reaction of both iron-containing microperoxidase-8 (Fe(III)MP-8) and manganese-containing microperoxidase-8 (Mn(III)MP-8) with H(2)O(2). The intermediate was assigned to be (hydro)peroxo-iron. With both mini-catalysts the final state obtained after 30-40 ms showed a resemblance to PorM(IV)MP-8[double bond]O(R(+)*); (R(+)*) is a radical located at the peptide. Quantum mechanical calculations indicate that hydroperoxo-iron is inactive as a catalytic intermediate in cytochrome P450 (P450)-type catalysis. Instead, the calculations suggest that peroxo-iron acts as the catalytic intermediate in P450-type catalysis. In addition, the calculations demonstrate that, although less likely, the possibility that oxenoid-iron acts as a catalytic intermediate in P450 catalysis cannot be fully excluded. An interesting aspect of the reactions catalysed by MP-8 is the possibility that, in view of the reversibility of the reactions between (hydro)peroxo-iron and oxenoid-iron, H(2)O plays a decisive role, at least in some cytochromes P450, in the removal of halogens, avoiding the production of compounds hazardous to the organism.
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Affiliation(s)
- Cees Veeger
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
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12
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Zakhariev O, Trautwein AX, Veeger C. Porphyrin-Fe(III)-hydroperoxide and porphyrin-Fe(III)-peroxide anion as catalytic intermediates in cytochrome P450-catalyzed hydroxylation reactions: a molecular orbital study. Biophys Chem 2000; 88:11-34. [PMID: 11152267 DOI: 10.1016/s0301-4622(00)00194-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hydroxylation of fluorobenzene and aniline, catalyzed by the porphyrin-Fe(III)-peroxide anion with either a cysteinate- or a histidyl-type of axial ligand as well as the hydroxylation of fluorobenzene, catalyzed by porphyrin-Fe(III)-hydroperoxide with a cysteinate-type of axial ligand as catalytic intermediates, have been investigated by electronic structure calculations in local spin-density approximation. Non-repulsive potential curves are, in contrast with porphyrin-Fe(III)-hydroperoxide, obtained only in the case of porphyrin-Fe(III)-peroxide anion as catalytic intermediate. The mutual substrate-porphyrin orientation with a dihedral angle between the plane of the substrate and the porphyrin plane of 45 degrees is more favorable compared with the parallel orientation between these two planes. This orientation differs for the case of fluorobenzene hydroxylation from the corresponding one calculated by us with the ferryl-oxo-pi-cation radical complex as a catalytic intermediate. The calculated reaction profiles show also the effectiveness of the histidyl-type coordinated porphyrin-Fe(III)-peroxide involved in P450 type of hydroxylation reactions. The calculations demonstrate the predominant role of the O1-O2 moiety of the porphyrin-Fe(III)-peroxide anion in the hydroxylation process of the substrates. The results indicate that the porphyrin-Fe(III)-peroxide anion is an effective catalytic species in hydroxylation reactions. In all the studied cases irrespective of the substrate and the nature of the axial ligand, the potential curves reach minimum at approximately 130-140 pm, expressing the length of an aromatic C-O bond.
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Affiliation(s)
- O Zakhariev
- Institute of Physics, Medical University Lübeck, Germany.
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