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Zhang E, Hirao H. Exploring the Bonding Nature of Iron(IV)-Oxo Species through Valence Bond Calculations and Electron Density Analysis. J Phys Chem A 2024; 128:7167-7176. [PMID: 39163412 DOI: 10.1021/acs.jpca.4c04335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Compound I (Cpd I) plays a pivotal role in substrate transformations within the catalytic cycle of cytochrome P450 enzymes (P450s). A key constituent of Cpd I is the iron(IV)-oxo unit, a structural motif also found in other heme enzymes and nonheme enzymes. In this study, we performed ab initio valence bond (VB) calculations, employing the valence bond self-consistent field (VBSCF) and breathing orbital valence bond (BOVB) methods, to unveil the bonding nature of this vital "Fe(IV)═O″ unit in bioinorganic chemistry. Comparisons were drawn with the triplet O2 molecule, which shares some electronic characteristics with iron(IV)-oxo. Additionally, Cpd I models of horseradish peroxidase (HRP) and catalase (CAT) were analyzed to assess the proximal ligand effect on the electronic structure of iron(IV)-oxo. Our VB analysis underscores the significant role of noncovalent resonance effects in shaping the iron(IV)-oxo bonding. The resonance stabilization within the π and σ frameworks occurs to comparable degrees, with additional stabilization resulting from resonance between VB structures from these frameworks. Furthermore, we elucidated the substantial influence of proximal and equatorial ligands in modulating the relative significance of different VB structures. Notably, in the presence of these ligands, iron(IV)-oxo is better described as iron(III)-oxyl or iron(II)-oxygen, displaying weak covalent character but enhanced by resonance effects. Although both species exhibit diradicaloid characters, resonance stabilization in iron(IV)-oxo is weaker than in O2. Further exploration using the Laplacian of electron density shows that, unlike O2, which exhibits a charge concentration region between its two oxygen atoms, iron(IV)-oxo species display a charge depletion region.
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Affiliation(s)
- Enhua Zhang
- Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, P. R. China
| | - Hajime Hirao
- Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, P. R. China
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2
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Li X, Liu Y. Multiscale Study on the Intramolecular C-S Bond Formation Catalyzed by P450 Monooxygenase CxnD Involved in the Biosynthesis of Chuangxinmycin: The Critical Roles of Noncrystal Water Molecule and Conformational Change. Inorg Chem 2024; 63:4086-4098. [PMID: 38376137 DOI: 10.1021/acs.inorgchem.3c03748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Cytochrome P450 monooxygenase CxnD catalyzes intramolecular C-S bond formation in the biosynthesis of chuangxinmycin, which is representative of the synthesis of sulfur-containing natural heterocyclic compounds. The intramolecular cyclization usually requires the activation of two reaction sites and a large conformational change; thus, illuminating its detailed reaction mechanism remains challengeable. Here, the reaction pathway of CxnD-catalyzed C-S bond formation was clarified by a series of calculations, including Gaussian accelerated molecular dynamics simulations and quantum mechanical-molecular mechanical calculations. Our results revealed that the C-S formation follows a diradical coupling mechanism. CxnD first employs Cpd I to abstract the hydrogen atom from the imino group of the indole ring, and then, the resulted Cpd II further extracts another hydrogen atom from the thiol group of the side chain to afford a diradical intermediate, in which a noncrystal water molecule entering into the active site after the formation of Cpd I was proved to play an indispensable role. Moreover, the diradical intermediate cannot directly perform the coupling reaction. It should first undergo a series of conformational changes leading to the proximity of two reaction sites. It is the flexibility of the active site of the enzyme and the side chain of the substrate that makes the diradical coupling to be successful.
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Affiliation(s)
- Xinyi Li
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
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3
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Costa GJ, Egbemhenghe A, Liang R. Computational Characterization of the Reactivity of Compound I in Unspecific Peroxygenases. J Phys Chem B 2023; 127:10987-10999. [PMID: 38096487 DOI: 10.1021/acs.jpcb.3c06311] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Unspecific peroxygenases (UPOs) are emerging as promising biocatalysts for selective oxyfunctionalization of unactivated C-H bonds. However, their potential in large-scale synthesis is currently constrained by suboptimal chemical selectivity. Improving the selectivity of UPOs requires a deep understanding of the molecular basis of their catalysis. Recent molecular simulations have sought to unravel UPO's selectivity and inform their design principles. However, most of these studies focused on substrate-binding poses. Few researchers have investigated how the reactivity of CpdI, the principal oxidizing intermediate in the catalytic cycle, influences selectivity in a realistic protein environment. Moreover, the influence of protein electrostatics on the reaction kinetics of CpdI has also been largely overlooked. To bridge this gap, we used multiscale simulations to interpret the regio- and enantioselective hydroxylation of the n-heptane substrate catalyzed by Agrocybe aegerita UPO (AaeUPO). We comprehensively characterized the energetics and kinetics of the hydrogen atom-transfer (HAT) step, initiated by CpdI, and the subsequent oxygen rebound step forming the product. Notably, our approach involved both free energy and potential energy evaluations in a quantum mechanics/molecular mechanics (QM/MM) setting, mitigating the dependence of results on the choice of initial conditions. These calculations illuminate the thermodynamics and kinetics of the HAT and oxygen rebound steps. Our findings highlight that both the conformational selection and the distinct chemical reactivity of different substrate hydrogen atoms together dictate the regio- and enantio-selectivity. Building on our previous study of CpdI's formation in AaeUPO, our results indicate that the HAT step is the rate-limiting step in the overall catalytic cycle. The subsequent oxygen rebound step is swift and retains the selectivity determined by the HAT step. We also pinpointed several polar and charged amino acid residues whose electrostatic potentials considerably influence the reaction barrier of the HAT step. Notably, the Glu196 residue is pivotal for both the CpdI's formation and participation in the HAT step. Our research offers in-depth insights into the catalytic cycle of AaeUPO, which will be instrumental in the rational design of UPOs with enhanced properties.
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Affiliation(s)
- Gustavo J Costa
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Abel Egbemhenghe
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Ruibin Liang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, United States
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4
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Reliably assessing the electronic structure of cytochrome P450 on today's classical computers and tomorrow's quantum computers. Proc Natl Acad Sci U S A 2022; 119:e2203533119. [PMID: 36095200 PMCID: PMC9499570 DOI: 10.1073/pnas.2203533119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Chemical simulation is one of the most promising applications for future quantum computers. It is thought that quantum computers may enable accurate simulation for complex molecules that are otherwise impossible to simulate classically; that is, it displays quantum advantage. To better understand quantum advantage in chemical simulation, we explore what quantum and classical resources are required to simulate a series of pharmaceutically relevant molecules. Using classical methods, we show that reliable classical simulation of these molecules requires significant resources and therefore is a promising candidate for quantum simulation. We estimate the quantum resources, both in overall simulation time and the size. The insights from this study pave the way for future quantum simulation of complex molecules. An accurate assessment of how quantum computers can be used for chemical simulation, especially their potential computational advantages, provides important context on how to deploy these future devices. To perform this assessment reliably, quantum resource estimates must be coupled with classical computations attempting to answer relevant chemical questions and to define the classical algorithms simulation frontier. Herein, we explore the quantum computation and classical computation resources required to assess the electronic structure of cytochrome P450 enzymes (CYPs) and thus define a classical–quantum advantage boundary. This is accomplished by analyzing the convergence of density matrix renormalization group plus n-electron valence state perturbation theory (DMRG+NEVPT2) and coupled-cluster singles doubles with noniterative triples [CCSD(T)] calculations for spin gaps in models of the CYP catalytic cycle that indicate multireference character. The quantum resources required to perform phase estimation using qubitized quantum walks are calculated for the same systems. Compilation into the surface code provides runtime estimates to compare directly to DMRG runtimes and to evaluate potential quantum advantage. Both classical and quantum resource estimates suggest that simulation of CYP models at scales large enough to balance dynamic and multiconfigurational electron correlation has the potential to be a quantum advantage problem and emphasizes the important interplay between classical computations and quantum algorithms development for chemical simulation.
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5
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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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6
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Hui C, Singh W, Quinn D, Li C, Moody TS, Huang M. Regio- and stereoselectivity in the CYP450BM3-catalyzed hydroxylation of complex terpenoids: a QM/MM study. Phys Chem Chem Phys 2020; 22:21696-21706. [DOI: 10.1039/d0cp03083j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The selective oxidation of C–H in artemisinin by P450BM3 variants was disclosed by combining QM/MM and MD simulations.
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Affiliation(s)
- Chenggong Hui
- Department of Chemistry & Chemical Engineering
- Queen's University
- Belfast
- UK
| | - Warispreet Singh
- Department of Chemistry & Chemical Engineering
- Queen's University
- Belfast
- UK
- Almac Sciences
| | - Derek Quinn
- Almac Sciences
- Department of Biocatalysis and Isotope Chemistry
- Craigavon BT63 5QD
- UK
| | - Chun Li
- Institute for Synthetic Biosystem/Department of Biochemical Engineering
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Thomas S. Moody
- Almac Sciences
- Department of Biocatalysis and Isotope Chemistry
- Craigavon BT63 5QD
- UK
- Arran Chemical Company Limited
| | - Meilan Huang
- Department of Chemistry & Chemical Engineering
- Queen's University
- Belfast
- UK
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7
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Lu Q, Song J, Wu P, Li C, Thiel W. Mechanistic Insights into the Directing Effect of Thr303 in Ethanol Oxidation by Cytochrome P450 2E1. ACS Catal 2019. [DOI: 10.1021/acscatal.9b00907] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Qianqian Lu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, Fujian 361005, China
| | - Jinshuai Song
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, Fujian 361005, China
| | - Peng Wu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunsen Li
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, Fujian 361005, China
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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8
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Mallick D, Shaik S. Kinetic Isotope Effect Probes the Reactive Spin State, As Well As the Geometric Feature and Constitution of the Transition State during H-Abstraction by Heme Compound II Complexes. J Am Chem Soc 2017; 139:11451-11459. [PMID: 28737390 DOI: 10.1021/jacs.7b04247] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
What do experimentally measured kinetic isotope effects (KIEs) tell us about H-abstraction reactions with multispin-state reactivity options? Using DFT calculations with tunneling corrections for experimentally studied H-abstraction reactions of porphyrin-Compound II species (Chem.-Eur. J. 2014, 20, 14437; Angew. Chem., Int. Ed. 2008, 47, 7321) with cyclohexane, dihydroanthracene (DHA), and xanthene (Xan), we show here that KIE is a selective probe that identifies the experimentally reactive spin state. At the same time, comparison of calculated and experimental KIE values permits us to determine the structural orientation of the transition states, as well as the presence/absence of an axial ligand, and the effect of porphyrin substituents. The studied compound II (Cpd II) species involve porphine, and porphyrin ligands with different meso-substituents, TPFPP (tetrakis(pentafluorophenyl)porphyrin dianion) and TMP (tetramesitylporphyrin dianion), with and without imidazole axial ligands. The DFT calculations reveal three potential pathways: quintet and triplet σ-pathways (5Hσ and 3Hσ) that possess linear transition state (TS) structures, and a triplet π -pathway (3Hπ) having a bent TS structure. Without an axial ligand, the 5Hσ pathways for these Cpd II complexes cross below the triplet states. The axial ligand raises the barriers for the quintet and triplet σ-pathways and quenches any chances for two-state reactivity, thus proceeding via the 3Hπ pathway. All of these pathways exhibit characteristic KIE values: very large for 3Hπ (48-200), small for 5Hσ (3-9), and intermediate for 3Hσ (23-51). The calculated KIEs for (TPFPP)FeIV═O without an axial ligand reveal that 3Hσ is the only pathway having a KIE that matches the experimental values, for the reactions with DHA and Xan (Angew. Chem., Int. Ed. 2008, 47, 7321). Indeed, theory shows that tunneling significantly lowers the 3Hσ barrier rendering it the sole reactive state for the reaction. A prediction is made for the reactivity and KIE of (TMP)FeIV═O complex, and a comparison is made with the analogous nonheme complexes.
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Affiliation(s)
- Dibyendu Mallick
- Institute of Chemistry and the Lise Meitner Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
| | - Sason Shaik
- Institute of Chemistry and the Lise Meitner Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
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9
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Lai R, Li H. Hydrogen Abstraction of Camphor Catalyzed by Cytochrome P450 cam: A QM/MM Study. J Phys Chem B 2016; 120:12312-12320. [PMID: 27934231 DOI: 10.1021/acs.jpcb.6b09923] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A combined quantum mechanics and molecular mechanics (QM/MM, QM = UB3LYP-D3, MM = AMBER) method is used to study the hydrogen abstraction reaction in P450cam catalyzed hydroxylation of camphor in the quartet state. Compared to QM/MM calculations in the literature, this study uses larger basis sets for the most important atoms at the active site and QM/MM Hessian harmonic frequency calculations to determine the standard Gibbs free energy of activation and kinetic isotope effect. The QM/MM covalent boundary is treated with a capping hydrogen atom method, which is simple and robust. An energy barrier of 21.3 kcal/mol and a standard free energy of activation of 16.8 kcal/mol are obtained for this hydrogen abstraction reaction. These values are similar to those reported in the literature, suggesting that when a general protocol is followed, QM/MM results are reproducible. It is found that using a sufficiently large basis set is important to minimize basis set errors.
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Affiliation(s)
- Rui Lai
- Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln , Lincoln, Nebraska 68588-0304, United States
| | - Hui Li
- Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln , Lincoln, Nebraska 68588-0304, United States
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10
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Dutta D, Mishra S. Loss of Catalytic Activity in the E134D, H67A, and H349A Mutants of DapE: Mechanistic Analysis with QM/MM Investigation. J Phys Chem B 2016; 120:11654-11664. [DOI: 10.1021/acs.jpcb.6b07446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Debodyuti Dutta
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Sabyashachi Mishra
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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11
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Castro L, Crawford LE, Mutengwa A, Götze JP, Bühl M. Insights into structure and redox potential of lignin peroxidase from QM/MM calculations. Org Biomol Chem 2016; 14:2385-2389. [PMID: 26815633 DOI: 10.1039/c6ob00037a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Redox potentials are computed for the active form (compound I) of lignin peroxidase (LiP) using a suitable QM/MM methodology (B3LYP/SDD/6-311G**//BP86/SVP:CHARMM). Allowing for dynamic conformational averaging, a potential of 0.67(33) V relative to ferrocenium/ferrocene is obtained for the active form with its oxoiron(iv) core. The computed redox potential is very sensitive to the charge distribution around the active site: protonation of titratable residues close to the metal center increases the redox potential, thereby rationalising the known pH dependence of LiP activity. A simple MM-charge deletion scheme is used to identify residues that are critical for the redox potential. Two mutant proteins are studied through homology modelling, E40Q and D183N, which are predicted to have an increased redox potential by 140 mV and 190 mV, respectively, relative to the wild type. These mutant proteins are thus promising targets for synthesis and further exploration toward a rational design of biocatalytic systems for oxidative degradation of lignin.
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Affiliation(s)
- Ludovic Castro
- EastChem School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - L Ellis Crawford
- EastChem School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Archford Mutengwa
- EastChem School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Jan P Götze
- EastChem School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Michael Bühl
- EastChem School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
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12
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Viciano I, Martí S. Theoretical Study of the Mechanism of Exemestane Hydroxylation Catalyzed by Human Aromatase Enzyme. J Phys Chem B 2016; 120:3331-43. [PMID: 26972150 DOI: 10.1021/acs.jpcb.6b01014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human aromatase (CYP19A1) aromatizes the androgens to form estrogens via a three-step oxidative process. The estrogens are necessary in humans, mainly in women, because of the role they play in sexual and reproductive development. However, these also are involved in the development and growth of hormone-dependent breast cancer. Therefore, inhibition of the enzyme aromatase, by means of drugs known as aromatase inhibitors, is the frontline therapy for these types of cancers. Exemestane is a suicidal third-generation inhibitor of aromatase, currently used in breast cancer treatment. In this study, the hydroxylation of exemestane catalyzed by aromatase has been studied by means of hybrid QM/MM methods. The Free Energy Perturbation calculations provided a free energy of activation for the hydrogen abstraction step (rate-limiting step) of 17 kcal/mol. The results reveal that the hydroxylation of exemestane is not the inhibition stage, suggesting a possible competitive mechanism between the inhibitor and the natural substrate androstenedione in the first catalytic subcycle of the enzyme. Furthermore, the analysis of the interaction energy for the substrate and the cofactor in the active site shows that the role of the enzymatic environment during this reaction consists of a transition state stabilization by means of electrostatic effects.
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Affiliation(s)
- Ignacio Viciano
- Departament de Química Física i Analítica, Universitat Jaume I , 12071 Castelló, Spain
| | - Sergio Martí
- Departament de Química Física i Analítica, Universitat Jaume I , 12071 Castelló, Spain
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13
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Saitow M, Kurashige Y, Yanai T. Fully Internally Contracted Multireference Configuration Interaction Theory Using Density Matrix Renormalization Group: A Reduced-Scaling Implementation Derived by Computer-Aided Tensor Factorization. J Chem Theory Comput 2015; 11:5120-31. [DOI: 10.1021/acs.jctc.5b00270] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masaaki Saitow
- The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Yuki Kurashige
- The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department
of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
- Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Takeshi Yanai
- The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department
of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
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14
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Altun A. Combined QM/MM studies on spectroscopic parameters of Compound I, Compound II, and related intermediates of cytochrome P450cam. COMPUT THEOR CHEM 2015. [DOI: 10.1016/j.comptc.2015.04.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Viciano I, Castillo R, Martí S. QM/MM modeling of the hydroxylation of the androstenedione substrate catalyzed by cytochrome P450 aromatase (CYP19A1). J Comput Chem 2015; 36:1736-47. [DOI: 10.1002/jcc.23967] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 04/07/2015] [Accepted: 05/16/2015] [Indexed: 01/30/2023]
Affiliation(s)
- Ignacio Viciano
- Departament de Química Física i Analítica; Universitat Jaume I; Castelló 12071 Spain
| | - Raquel Castillo
- Departament de Química Física i Analítica; Universitat Jaume I; Castelló 12071 Spain
| | - Sergio Martí
- Departament de Química Física i Analítica; Universitat Jaume I; Castelló 12071 Spain
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16
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Wang B, Li C, Dubey KD, Shaik S. Quantum mechanical/molecular mechanical calculated reactivity networks reveal how cytochrome P450cam and Its T252A mutant select their oxidation pathways. J Am Chem Soc 2015; 137:7379-90. [PMID: 26011529 DOI: 10.1021/jacs.5b02800] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantum mechanical/molecular mechanical calculations address the longstanding-question of a "second oxidant" in P450 enzymes wherein the proton-shuttle, which leads to formation of the "primary-oxidant" Compound I (Cpd I), was severed by mutating the crucial residue (in P450cam: Threonine-252-to-Alanine, hence T252A). Investigating the oxidant candidates Cpd I, ferric hydroperoxide, and ferric hydrogen peroxide (Fe(III)(O2H2)), and their reactions, generates reactivity networks which enable us to rule out a "second oxidant" and at the same time identify an additional coupling pathway that is responsible for the epoxidation of 5-methylenylcamphor by the T252A mutant. In this "second-coupling pathway", the reaction starts with the Fe(III)(O2H2) intermediate, which transforms to Cpd I via a O-O homolysis/H-abstraction mechanism. The persistence of Fe(III)(O2H2) and its oxidative reactivity are shown to be determined by interplay of substrate and protein. The substrate 5-methylenylcamphor prevents H2O2 release, while the protein controls the Fe(III)(O2H2) conversion to Cpd I by nailing-through hydrogen-bonding interactions-the conformation of the HO(•) radical produced during O-O homolysis. This conformation prevents HO(•) attack on the porphyrin's meso position, as in heme oxygenase, and prefers H-abstraction from Fe(IV)OH thereby generating H2O + Cpd I. Cpd I then performs substrate oxidations. Camphor cannot prevent H2O2 release and hence the T252A mutant does not oxidize camphor. This "second pathway" transpires also during H2O2 shunting of the cycle of wild-type P450cam, where the additional hydrogen-bonding with Thr252 prevents H2O2 release, and contributes to a successful Cpd I formation. The present results lead to a revised catalytic cycle of Cytochrome P450cam.
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Affiliation(s)
- Binju Wang
- †Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Chunsen Li
- ‡State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.,§Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, Fujian 361005, China
| | - Kshatresh Dutta Dubey
- †Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Sason Shaik
- †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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17
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Krámos B, Oláh J. The mechanism of human aromatase (CYP 19A1) revisited: DFT and QM/MM calculations support a compound I-mediated pathway for the aromatization process. Struct Chem 2014. [DOI: 10.1007/s11224-014-0545-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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18
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Wang B, Usharani D, Li C, Shaik S. Theory uncovers an unusual mechanism of DNA repair of a lesioned adenine by AlkB enzymes. J Am Chem Soc 2014; 136:13895-901. [PMID: 25203306 DOI: 10.1021/ja507934g] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
DNA-base lesions cause cancer and propagate into the genome. We use in-protein QM/MM calculations to study the repair of etheno-bridged adenine (εA) by the iron(IV)-oxo species of AlkB enzymes. Recent experimental investigations, using mass-spectrometry and in crystallo isolation, suggested that εA was repaired by formation of an epoxide (εA-ep) that further transforms to a glycol (εA-gl), ending finally in adenine and glyoxal. Theory reproduces the experimentally observed barrier for the rate-determining step and its pH dependence. However, as we show, the mass-spectrometrically identified species are side-byproducts unassociated with the repair mechanism. The repair is mediated by a zwitterionic species, of the same molecular mass as the epoxide, which transforms to an intermediate that matches the in crystallo trapped species in structure and mass, but is NOT the assumed εA-gl iron-glycol complex. Verifiable/falsifiable predictions, regarding the key protein residues, follow. The paper underscores the indispensable role of theory by providing atomistic descriptions of this vital mechanism, and guiding further experimental investigations.
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Affiliation(s)
- Binju Wang
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, Hebrew University of Jerusalem , 91904 Jerusalem, Israel
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19
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Altun A, Breidung J, Neese F, Thiel W. Correlated Ab Initio and Density Functional Studies on H2 Activation by FeO+. J Chem Theory Comput 2014; 10:3807-20. [DOI: 10.1021/ct500522d] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Ahmet Altun
- Department
of Physics, Fatih University, 34500 B.Çekmece, Istanbul, Turkey
| | - Jürgen Breidung
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz
1, D-45470 Mülheim
an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut
für Chemische Energiekonversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Walter Thiel
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz
1, D-45470 Mülheim
an der Ruhr, Germany
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20
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Hirao H, Thellamurege N, Zhang X. Applications of density functional theory to iron-containing molecules of bioinorganic interest. Front Chem 2014; 2:14. [PMID: 24809043 PMCID: PMC4010748 DOI: 10.3389/fchem.2014.00014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 03/10/2014] [Indexed: 12/29/2022] Open
Abstract
The past decades have seen an explosive growth in the application of density functional theory (DFT) methods to molecular systems that are of interest in a variety of scientific fields. Owing to its balanced accuracy and efficiency, DFT plays particularly useful roles in the theoretical investigation of large molecules. Even for biological molecules such as proteins, DFT finds application in the form of, e.g., hybrid quantum mechanics and molecular mechanics (QM/MM), in which DFT may be used as a QM method to describe a higher prioritized region in the system, while a MM force field may be used to describe remaining atoms. Iron-containing molecules are particularly important targets of DFT calculations. From the viewpoint of chemistry, this is mainly because iron is abundant on earth, iron plays powerful (and often enigmatic) roles in enzyme catalysis, and iron thus has the great potential for biomimetic catalysis of chemically difficult transformations. In this paper, we present a brief overview of several recent applications of DFT to iron-containing non-heme synthetic complexes, heme-type cytochrome P450 enzymes, and non-heme iron enzymes, all of which are of particular interest in the field of bioinorganic chemistry. Emphasis will be placed on our own work.
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Affiliation(s)
- Hajime Hirao
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological UniversitySingapore, Singapore
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21
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Ripa L, Mee C, Sjö P, Shamovsky I. Theoretical Studies of the Mechanism of N-Hydroxylation of Primary Aromatic Amines by Cytochrome P450 1A2: Radicaloid or Anionic? Chem Res Toxicol 2014; 27:265-78. [DOI: 10.1021/tx400376u] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lena Ripa
- Department of Medicinal Chemistry, RIA iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Christine Mee
- Genetic Toxicology, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, U.K
| | - Peter Sjö
- Department of Medicinal Chemistry, RIA iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Igor Shamovsky
- Department of Medicinal Chemistry, RIA iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
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22
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Krámos B, Oláh J. Enolization as an Alternative Proton Delivery Pathway in Human Aromatase (P450 19A1). J Phys Chem B 2014; 118:390-405. [DOI: 10.1021/jp407365x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Balázs Krámos
- Department of Inorganic and
Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary
| | - Julianna Oláh
- Department of Inorganic and
Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary
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23
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Das PK, Chatterjee S, Samanta S, Dey A. EPR, resonance Raman, and DFT calculations on thiolate- and imidazole-bound iron(III) porphyrin complexes: role of the axial ligand in tuning the electronic structure. Inorg Chem 2012; 51:10704-14. [PMID: 23013308 DOI: 10.1021/ic3016035] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Iron(III) porphyrin complexes bearing covalently attached imidazole and thiolate axial ligands are investigated using resonance Raman, electron paramagnetic resonance, and cyclic voltammetry. The thiolate ligand stabilizes a low-spin ground state in solvent-bound six-coordinate species, weakens the Fe-N(pyr) bonds, and shifts the Fe(III/II) potential more negative by ~500 mV relative to an imidazole-bound species. Density functional theory calculations reproduce the experimental observation and indicate that the covalent charge donation from thiolate to iron reduces the Z(eff) on the iron. This increases the Fe(3d) orbital energies, which changes the bonding interaction present in these complexes significantly. In particular, the increase of the Fe(3d) energies activates an iron-to-porphyrin π*-back-bonding interaction not present in the imidazole-bound complex.
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Affiliation(s)
- Pradip Kumar Das
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata, India 700032
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24
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Blanchard S, Derat E, Desage‐El Murr M, Fensterbank L, Malacria M, Mouriès‐Mansuy V. Non‐Innocent Ligands: New Opportunities in Iron Catalysis. Eur J Inorg Chem 2011. [DOI: 10.1002/ejic.201100985] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sébastien Blanchard
- Institut Parisien de Chimie Moléculaire (IPCM, UMR CNRS 7201), Université Pierre & Marie Curie (UPMC), cc 229, 4, place Jussieu, 75252 Paris Cedex 05, France, Fax: +33‐1‐44277360
| | - Etienne Derat
- Institut Parisien de Chimie Moléculaire (IPCM, UMR CNRS 7201), Université Pierre & Marie Curie (UPMC), cc 229, 4, place Jussieu, 75252 Paris Cedex 05, France, Fax: +33‐1‐44277360
| | - Marine Desage‐El Murr
- Institut Parisien de Chimie Moléculaire (IPCM, UMR CNRS 7201), Université Pierre & Marie Curie (UPMC), cc 229, 4, place Jussieu, 75252 Paris Cedex 05, France, Fax: +33‐1‐44277360
| | - Louis Fensterbank
- Institut Parisien de Chimie Moléculaire (IPCM, UMR CNRS 7201), Université Pierre & Marie Curie (UPMC), cc 229, 4, place Jussieu, 75252 Paris Cedex 05, France, Fax: +33‐1‐44277360
| | - Max Malacria
- Institut Parisien de Chimie Moléculaire (IPCM, UMR CNRS 7201), Université Pierre & Marie Curie (UPMC), cc 229, 4, place Jussieu, 75252 Paris Cedex 05, France, Fax: +33‐1‐44277360
| | - Virginie Mouriès‐Mansuy
- Institut Parisien de Chimie Moléculaire (IPCM, UMR CNRS 7201), Université Pierre & Marie Curie (UPMC), cc 229, 4, place Jussieu, 75252 Paris Cedex 05, France, Fax: +33‐1‐44277360
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25
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Shahrokh K, Orendt A, Yost GS, Cheatham TE. Quantum mechanically derived AMBER-compatible heme parameters for various states of the cytochrome P450 catalytic cycle. J Comput Chem 2011; 33:119-33. [PMID: 21997754 DOI: 10.1002/jcc.21922] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/28/2011] [Accepted: 07/30/2011] [Indexed: 01/31/2023]
Abstract
Molecular mechanics (MM) methods are computationally affordable tools for screening chemical libraries of novel compounds for sites of P450 metabolism. One challenge for MM methods has been the absence of a consistent and transferable set of parameters for the heme within the P450 active site. Experimental data indicate that mammalian P450 enzymes vary greatly in the size, architecture, and plasticity of their active sites. Thus, obtaining X-ray-based geometries for the development of accurate MM parameters for the major classes of hepatic P450 remains a daunting task. Our previous work with preliminary gas-phase quantum mechanics (QM)-derived atomic partial charges greatly improved the accuracy of docking studies of raloxifene to CYP3A4. We have therefore developed and tested a consistent set of transferable MM parameters based on gas-phase QM calculations of two model systems of the heme-a truncated (T-HM) and a full (F-HM) for four states of the P450 catalytic cycle. Our results indicate that the use of the atomic partial charges from the F-HM further improves the accuracy of docked predictions for raloxifene to CYP3A4. Different patterns for substrate docking are also observed depending on the choice of heme model and state. Newly parameterized heme models are tested in implicit and explicitly solvated MD simulations in the absence and presence of enzyme structures, for CYP3A4, and appear to be stable on the nanosecond simulation timescale. The new force field for the various heme states may aid the community for simulations of P450 enzymes and other heme-containing enzymes.
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Affiliation(s)
- Kiumars Shahrokh
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, USA
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26
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Chen H, Lai W, Shaik S. Multireference and multiconfiguration ab initio methods in heme-related systems: what have we learned so far? J Phys Chem B 2011; 115:1727-42. [PMID: 21344948 DOI: 10.1021/jp110016u] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This work reviews the recent applications of ab initio multireference/multiconfiguration (MR/MC) electronic structure methods to heme-related systems, involving tetra-, penta-, and hexa-coordinate species, as well as the high-valent iron-oxo species. The current accuracy of these methods in the various systems is discussed, with special attention to potential sources of systematic errors. Thus, the review summarizes and tries to rationalize the key elements of MR/MC calculations, namely, the choice of the employed active space, especially the so-called double-shell effect that has already been recognized to be important in transition-metal-containing systems, and the impact of these elements on the spin-state energetics of heme species, as well as on the bonding mechanism of small molecules to the heme. It is shown that expansion of the MC wave function into one based on localized orbitals provides a compact and insightful view on some otherwise complex electronic structures. The effects of protein environment on the MR/MC results are summarized for the few available quantum mechanical/molecular mechanical (QM/MM) studies. Comparisons with corresponding DFT results are also made wherever available. Potential future directions are proposed.
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Affiliation(s)
- Hui Chen
- Institute of Chemistry, Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel.
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27
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Bochevarov AD, Li J, Song WJ, Friesner RA, Lippard SJ. Insights into the different dioxygen activation pathways of methane and toluene monooxygenase hydroxylases. J Am Chem Soc 2011; 133:7384-97. [PMID: 21517016 PMCID: PMC3092846 DOI: 10.1021/ja110287y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The methane and toluene monooxygenase hydroxylases (MMOH and TMOH, respectively) have almost identical active sites, yet the physical and chemical properties of their oxygenated intermediates, designated P*, H(peroxo), Q, and Q* in MMOH and ToMOH(peroxo) in a subclass of TMOH, ToMOH, are substantially different. We review and compare the structural differences in the vicinity of the active sites of these enzymes and discuss which changes could give rise to the different behavior of H(peroxo) and Q. In particular, analysis of multiple crystal structures reveals that T213 in MMOH and the analogous T201 in TMOH, located in the immediate vicinity of the active site, have different rotatory configurations. We study the rotational energy profiles of these threonine residues with the use of molecular mechanics (MM) and quantum mechanics/molecular mechanics (QM/MM) computational methods and put forward a hypothesis according to which T213 and T201 play an important role in the formation of different types of peroxodiiron(III) species in MMOH and ToMOH. The hypothesis is indirectly supported by the QM/MM calculations of the peroxodiiron(III) models of ToMOH and the theoretically computed Mössbauer spectra. It also helps explain the formation of two distinct peroxodiiron(III) species in the T201S mutant of ToMOH. Additionally, a role for the ToMOD regulatory protein, which is essential for intermediate formation and protein functioning in the ToMO system, is advanced. We find that the low quadrupole splitting parameter in the Mössbauer spectrum observed for a ToMOH(peroxo) intermediate can be explained by protonation of the peroxo moiety, possibly stabilized by the T201 residue. Finally, similarities between the oxygen activation mechanisms of the monooxygenases and cytochrome P450 are discussed.
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28
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Radoń M, Broclawik E, Pierloot K. DFT and Ab Initio Study of Iron-Oxo Porphyrins: May They Have a Low-Lying Iron(V)-Oxo Electromer? J Chem Theory Comput 2011; 7:898-908. [DOI: 10.1021/ct1006168] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mariusz Radoń
- Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060 Kraków, Poland
| | - Ewa Broclawik
- Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków, Poland
| | - Kristine Pierloot
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Heverlee-Leuven, Belgium
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29
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Alfonso-Prieto M, Oberhofer H, Klein ML, Rovira C, Blumberger J. Proton Transfer Drives Protein Radical Formation in Helicobacter pylori Catalase but Not in Penicillium vitale Catalase. J Am Chem Soc 2011; 133:4285-98. [DOI: 10.1021/ja1110706] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Alfonso-Prieto
- Computer Simulation & Modeling Laboratory, Parc Científic de Barcelona, Baldiri Reixac 4, 08028 Barcelona, Spain
- Institute for Computational Molecular Science, Temple University, 1900 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - H. Oberhofer
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - M. L. Klein
- Institute for Computational Molecular Science, Temple University, 1900 North 12th Street, Philadelphia, Pennsylvania 19122, United States
| | - C. Rovira
- Computer Simulation & Modeling Laboratory, Parc Científic de Barcelona, Baldiri Reixac 4, 08028 Barcelona, Spain
- Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - J. Blumberger
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
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30
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Cho KB, Lai W, Hamberg M, Raman C, Shaik S. The reaction mechanism of allene oxide synthase: Interplay of theoretical QM/MM calculations and experimental investigations. Arch Biochem Biophys 2011; 507:14-25. [DOI: 10.1016/j.abb.2010.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/28/2010] [Accepted: 07/16/2010] [Indexed: 11/28/2022]
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31
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Galinato MGI, Spolitak T, Ballou DP, Lehnert N. Elucidating the role of the proximal cysteine hydrogen-bonding network in ferric cytochrome P450cam and corresponding mutants using magnetic circular dichroism spectroscopy. Biochemistry 2011; 50:1053-69. [PMID: 21158478 DOI: 10.1021/bi101911y] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although extensive research has been performed on various cytochrome P450s, especially Cyt P450cam, there is much to be learned about the mechanism of how its functional unit, a heme b ligated by an axial cysteine, is finely tuned for catalysis by its second coordination sphere. Here we study how the hydrogen-bonding network affects the proximal cysteine and the Fe-S(Cys) bond in ferric Cyt P450cam. This is accomplished using low-temperature magnetic circular dichroism (MCD) spectroscopy on wild-type (wt) Cyt P450cam and on the mutants Q360P (pure ferric high-spin at low temperature) and L358P where the "Cys pocket" has been altered (by removing amino acids involved in the hydrogen-bonding network), and Y96W (pure ferric low-spin). The MCD spectrum of Q360P reveals fourteen electronic transitions between 15200 and 31050 cm(-1). Variable-temperature variable-field (VTVH) saturation curves were used to determine the polarizations of these electronic transitions with respect to in-plane (xy) and out-of-plane (z) polarization relative to the heme. The polarizations, oscillator strengths, and TD-DFT calculations were then used to assign the observed electronic transitions. In the lower energy region, prominent bands at 15909 and 16919 cm(-1) correspond to porphyrin (P) → Fe charge transfer (CT) transitions. The band at 17881 cm(-1) has distinct sulfur S(π) → Fe CT contributions. The Q band is observed as a pseudo A-term (derivative shape) at 18604 and 19539 cm(-1). In the case of the Soret band, the negative component of the expected pseudo A-term is split into two features due to mixing with another π → π* and potentially a P → Fe CT excited state. The resulting three features are observed at 23731, 24859, and 25618 cm(-1). Most importantly, the broad, prominent band at 28570 cm(-1) is assigned to the S(σ) → Fe CT transition, whose intensity is generated through a multitude of CT transitions with strong iron character. For wt, Q360P, and L358P, this band occurs at 28724, 28570, and 28620 cm(-1), respectively. The small shift of this feature upon altering the hydrogen bonds to the proximal cysteine indicates that the role of the Cys pocket is not primarily for electronic fine-tuning of the sulfur donor strength but is more for stabilizing the proximal thiolate against external reactants (NO, O(2), H(3)O(+)), and for properly positioning cysteine to coordinate to the iron center. This aspect is discussed in detail.
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Affiliation(s)
- Mary Grace I Galinato
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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32
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Chen H, Song J, Lai W, Wu W, Shaik S. Multiple Low-Lying States for Compound I of P450cam and Chloroperoxidase Revealed from Multireference Ab Initio QM/MM Calculations. J Chem Theory Comput 2010; 6:940-53. [DOI: 10.1021/ct9006234] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hui Chen
- Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, State Key Laboratory of Physical Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, P. R. China
| | - Jinshuai Song
- Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, State Key Laboratory of Physical Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, P. R. China
| | - Wenzhen Lai
- Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, State Key Laboratory of Physical Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, P. R. China
| | - Wei Wu
- Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, State Key Laboratory of Physical Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, P. R. China
| | - Sason Shaik
- Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, State Key Laboratory of Physical Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, P. R. China
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33
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Altun A, Yokoyama S, Morokuma K. Color tuning in short wavelength-sensitive human and mouse visual pigments: ab initio quantum mechanics/molecular mechanics studies. J Phys Chem A 2010; 113:11685-92. [PMID: 19630373 DOI: 10.1021/jp902754p] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated the protonation state and photoabsorption spectrum of Schiff-base (SB) nitrogen bound 11-cis-retinal in human blue and mouse UV cone visual pigments as well as in bovine rhodopsin by hybrid quantum mechanical/molecular mechanical (QM/MM) calculations. We have employed both multireference (MRCISD+Q, MR-SORCI+Q, and MR-DDCI2+Q) and single reference (TD-B3LYP and RI-CC2) QM methods. The calculated ground-state and vertical excitation energies show that UV-sensitive pigments have deprotonated SB nitrogen, while violet-sensitive pigments have protonated SB nitrogen, in agreement with some indirect experimental evidence. A significant blue shift of the absorption maxima of violet-sensitive pigments relative to rhodopsins arises from the increase in bond length alternation of the polyene chain of 11-cis-retinal induced by polarizing fields of these pigments. The main counterion is Glu113 in both violet-sensitive vertebrate pigments and bovine rhodopsin. Neither Glu113 nor the remaining pigment has a significant influence on the first excitation energy of 11-cis-retinal in the UV-sensitive pigments that have deprotonated SB nitrogen. There is no charge transfer between the SB and beta-ionone terminals of 11-cis-retinal in the ground and first excited states.
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Affiliation(s)
- Ahmet Altun
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
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34
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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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35
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Senn HM, Kästner J, Breidung J, Thiel W. Finite-temperature effects in enzymatic reactions — Insights from QM/MM free-energy simulations. CAN J CHEM 2009. [DOI: 10.1139/v09-092] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We report potential-energy and free-energy data for three enzymatic reactions: carbon–halogen bond formation in fluorinase, hydrogen abstraction from camphor in cytochrome P450cam, and chorismate-to-prephenate Claisen rearrangement in chorismate mutase. The results were obtained by combined quantum mechanics/molecular mechanics (QM/MM) optimizations and two types of QM/MM free-energy simulations (free-energy perturbation and umbrella sampling) using semi-empirical or density-functional QM methods. Based on these results and our previously published free-energy data on electrophilic substitution in para-hydroxybenzoate hydroxylase, we discuss the importance of finite-temperature effects in the chemical step of enzyme reactions. We find that the entropic contribution to the activation barrier is generally rather small, usually of the order of 5 kJ mol–1 or less, consistent with the notion that enzymes bind and pre-organize the reactants in the active site. A somewhat larger entropic contribution is encountered in the case of chorismate mutase where the pericyclic transition state is intrinsically more rigid than the chorismate reactant (also in the enzyme). The present results suggest that barriers from QM/MM geometry optimization may often be close to free-energy barriers for the chemical step in enzymatic reactions.
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Affiliation(s)
- Hans Martin Senn
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr, Germany
| | - Johannes Kästner
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr, Germany
| | - Jürgen Breidung
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr, Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr, Germany
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Lai W, Chen H, Shaik S. What Kinds of Ferryl Species Exist for Compound II of Chloroperoxidase? A Dialog of Theory with Experiment. J Phys Chem B 2009; 113:7912-7. [DOI: 10.1021/jp902288q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Wenzhen Lai
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Hui Chen
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
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Abstract
Combined quantum-mechanics/molecular-mechanics (QM/MM) approaches have become the method of choice for modeling reactions in biomolecular systems. Quantum-mechanical (QM) methods are required for describing chemical reactions and other electronic processes, such as charge transfer or electronic excitation. However, QM methods are restricted to systems of up to a few hundred atoms. However, the size and conformational complexity of biopolymers calls for methods capable of treating up to several 100,000 atoms and allowing for simulations over time scales of tens of nanoseconds. This is achieved by highly efficient, force-field-based molecular mechanics (MM) methods. Thus to model large biomolecules the logical approach is to combine the two techniques and to use a QM method for the chemically active region (e.g., substrates and co-factors in an enzymatic reaction) and an MM treatment for the surroundings (e.g., protein and solvent). The resulting schemes are commonly referred to as combined or hybrid QM/MM methods. They enable the modeling of reactive biomolecular systems at a reasonable computational effort while providing the necessary accuracy.
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Affiliation(s)
- Hans Martin Senn
- Department of Chemistry, WestCHEM and University of Glasgow, Glasgow G12 8QQ, UK.
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