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Marsch GA, Carlson BT, Guengerich FP. 7,8-benzoflavone binding to human cytochrome P450 3A4 reveals complex fluorescence quenching, suggesting binding at multiple protein sites. J Biomol Struct Dyn 2017; 36:841-860. [PMID: 28278026 DOI: 10.1080/07391102.2017.1301270] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Human cytochrome P450 (P450) 3A4 is involved in the metabolism of one-half of marketed drugs and shows cooperative interactions with some substrates and other ligands. The interaction between P450 3A4 and the known allosteric effector 7,8-benzoflavone (α-naphthoflavone, αNF) was characterized using steady-state fluorescence spectroscopy. The binding interaction of P450 3A4 and αNF effectively quenched the fluorescence of both the enzyme and ligand. The Hill Equation and Stern-Volmer fluorescence quenching models were used to evaluate binding of ligand to enzyme. P450 3A4 fluorescence was quenched by titration with αNF; at the relatively higher [αNF]/[P450 3A4] ratios in this experiment, two weaker quenching interactions were revealed (Kd 1.8-2.5 and 6.5 μM). A range is given for the stronger interaction since αNF quenching of P450 3A4 fluorescence changed the protein spectral profile: quenching of 315 nm emission was slightly more efficient (Kd 1.8 μM) than the quenching of protein fluorescence at 335 and 355 nm (Kd 2.5 and 2.1 μM, respectively). In the reverse titration, αNF fluorescence was quenched by P450 3A4; at the lower [αNF]/[P450 3A4] ratios here, two strong quenching interactions were revealed (Kd 0.048 and 1.0 μM). Thus, four binding interactions of αNF to P450 3A4 are suggested by this study, one of which may be newly recognized and which could affect studies of drug oxidations by this important enzyme.
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Affiliation(s)
- Glenn A Marsch
- a Physics Department , Grove City College , Grove City , PA , 16127-2104 , USA
| | - Benjamin T Carlson
- a Physics Department , Grove City College , Grove City , PA , 16127-2104 , USA
| | - F Peter Guengerich
- b Department of Biochemistry , Vanderbilt University School of Medicine , 638B Robinson Research Building, 2200 Pierce Avenue, Nashville , TN , 37232-0146 , USA
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Challenges in assignment of allosteric effects in cytochrome P450-catalyzed substrate oxidations to structural dynamics in the hemoprotein architecture. J Inorg Biochem 2017; 167:100-115. [DOI: 10.1016/j.jinorgbio.2016.11.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/17/2016] [Accepted: 11/22/2016] [Indexed: 12/19/2022]
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Wang M, Baaden M, Wang J, Liang Z. A cooperative mechanism of clotrimazoles in P450 revealed by the dissociation picture of clotrimazole from P450. J Chem Inf Model 2014; 54:1218-25. [PMID: 24611729 DOI: 10.1021/ci400660e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dissociation processes of clotrimazole (CLT) in several models are comparatively investigated by molecular dynamics simulations to explore the cooperative mechanism of clotrimazoles in P450. Our results suggest that when P450 only accommodates the active CLT (CLT1), CLT1 continually diffuses away from heme, and the partial BC loop (residues 73-88) and the extended FG loop (residues 173-186) first close and then open. When the enzyme binds to two CLT molecules, CLT1 basically keeps close to heme, and the partial BC loop and the extended FG loop move close to each other. Clearly, the effector CLT (CLT2) plays a cooperative role in the inhibition of CLT1 on P450. CLT2 restrains the dissociation of CLT1 first through direct π-π stacking interactions and then through the rearranged binding site induced by CLT2. The presence of CLT1 can help to stabilize the protein structure around CLT2 by interacting with M86, Q173, and M174.
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Affiliation(s)
- Mian Wang
- School of Chemistry and Chemical Engineering, Guangxi University , Nanning 530004, China
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Martin P, Giardiello M, McDonald TO, Rannard SP, Owen A. Mediation of in Vitro Cytochrome P450 Activity by Common Pharmaceutical Excipients. Mol Pharm 2013; 10:2739-48. [DOI: 10.1021/mp400175n] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Philip Martin
- Department of Molecular
and
Clinical Pharmacology, University of Liverpool, Block H, 70 Pembroke
Place, Liverpool, L69 3GF, U.K
| | - Marco Giardiello
- Department of Chemistry, University
of Liverpool, Crown Street, L69 3BX, U.K
| | - Tom O. McDonald
- Department of Chemistry, University
of Liverpool, Crown Street, L69 3BX, U.K
| | - Steven P. Rannard
- Department of Chemistry, University
of Liverpool, Crown Street, L69 3BX, U.K
- MRC Centre for Drug Safety Science,
University of Liverpool, Liverpool, L69 3GE, U.K
| | - Andrew Owen
- Department of Molecular
and
Clinical Pharmacology, University of Liverpool, Block H, 70 Pembroke
Place, Liverpool, L69 3GF, U.K
- MRC Centre for Drug Safety Science,
University of Liverpool, Liverpool, L69 3GE, U.K
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Hartman JH, Boysen G, Miller GP. Cooperative effects for CYP2E1 differ between styrene and its metabolites. Xenobiotica 2013; 43:755-64. [PMID: 23327532 DOI: 10.3109/00498254.2012.760764] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cooperative interactions are frequently observed in the metabolism of drugs and pollutants by cytochrome P450s; nevertheless, the molecular determinants for cooperativity remain elusive. Previously, we demonstrated that steady-state styrene metabolism by CYP2E1 exhibits positive cooperativity. We hypothesized that styrene metabolites have lower affinity than styrene toward CYP2E1 and limited ability to induce cooperative effects during metabolism. To test the hypothesis, we determined the potency and mechanism of inhibition for styrene and its metabolites toward oxidation of 4-nitrophenol using CYP2E1 Supersomes® and human liver microsomes. Styrene inhibited the reaction through a mixed cooperative mechanism with high affinity for the catalytic site (67 µM) and lower affinity for the cooperative site (1100 µM), while increasing substrate turnover at high concentrations. Styrene oxide and 4-vinylphenol possessed similar affinity for CYP2E1. Styrene oxide behaved cooperatively like styrene, but 4-vinylphenol decreased turnover at high concentrations. Styrene glycol was a very poor competitive inhibitor. Among all compounds, there was a positive correlation with binding and hydrophobicity. Taken together, these findings for CYP2E1 further validate contributions of cooperative mechanisms to metabolic processes, demonstrate the role of molecular structure on those mechanisms and underscore the potential for heterotropic cooperative effects between different compounds.
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Affiliation(s)
- Jessica H Hartman
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Zaretzki J, Rydberg P, Bergeron C, Bennett KP, Olsen L, Breneman CM. RS-Predictor models augmented with SMARTCyp reactivities: robust metabolic regioselectivity predictions for nine CYP isozymes. J Chem Inf Model 2012; 52:1637-59. [PMID: 22524152 DOI: 10.1021/ci300009z] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RS-Predictor is a tool for creating pathway-independent, isozyme-specific, site of metabolism (SOM) prediction models using any set of known cytochrome P450 (CYP) substrates and metabolites. Until now, the RS-Predictor method was only trained and validated on CYP 3A4 data, but in the present study, we report on the versatility the RS-Predictor modeling paradigm by creating and testing regioselectivity models for substrates of the nine most important CYP isozymes. Through curation of source literature, we have assembled 680 substrates distributed among CYPs 1A2, 2A6, 2B6, 2C19, 2C8, 2C9, 2D6, 2E1, and 3A4, the largest publicly accessible collection of P450 ligands and metabolites released to date. A comprehensive investigation into the importance of different descriptor classes for identifying the regioselectivity mediated by each isozyme is made through the generation of multiple independent RS-Predictor models for each set of isozyme substrates. Two of these models include a density functional theory (DFT) reactivity descriptor derived from SMARTCyp. Optimal combinations of RS-Predictor and SMARTCyp are shown to have stronger performance than either method alone, while also exceeding the accuracy of the commercial regioselectivity prediction methods distributed by Optibrium and Schrödinger, correctly identifying a large proportion of the metabolites in each substrate set within the top two rank-positions: 1A2 (83.0%), 2A6 (85.7%), 2B6 (82.1%), 2C19 (86.2%), 2C8 (83.8%), 2C9 (84.5%), 2D6 (85.9%), 2E1 (82.8%), 3A4 (82.3%), and merged (86.0%). Comprehensive datamining of each substrate set and careful statistical analyses of the predictions made by the different models revealed new insights into molecular features that control metabolic regioselectivity and enable accurate prospective prediction of likely SOMs.
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Affiliation(s)
- Jed Zaretzki
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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Conner KP, Woods C, Atkins WM. Interactions of cytochrome P450s with their ligands. Arch Biochem Biophys 2011; 507:56-65. [PMID: 20939998 PMCID: PMC3041843 DOI: 10.1016/j.abb.2010.10.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 10/01/2010] [Accepted: 10/04/2010] [Indexed: 01/12/2023]
Abstract
Cytochrome P450s (CYPs) are heme-containing monooxygenases that contribute to an enormous range of enzymatic function including biosynthetic and detoxification roles. This review summarizes recent studies concerning interactions of CYPs with ligands including substrates, inhibitors, and diatomic heme-ligating molecules. These studies highlight the complexity in the relationship between the heme spin state and active site occupancy, the roles of water in directing protein-ligand and ligand-heme interactions, and the details of interactions between heme and gaseous diatomic CYP ligands. Both kinetic and thermodynamic aspects of ligand binding are considered.
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Affiliation(s)
- Kip P. Conner
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 98195-7610
| | - Caleb Woods
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 98195-7610
| | - William M. Atkins
- Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 98195-7610
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Denisov IG, Frank DJ, Sligar SG. Cooperative properties of cytochromes P450. Pharmacol Ther 2009; 124:151-67. [PMID: 19555717 DOI: 10.1016/j.pharmthera.2009.05.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 05/28/2009] [Indexed: 02/07/2023]
Abstract
Cytochromes P450 form a large and important class of heme monooxygenases with a broad spectrum of substrates and corresponding functions, from steroid hormone biosynthesis to the metabolism of xenobiotics. Despite decades of study, the molecular mechanisms responsible for the complex non-Michaelis behavior observed with many members of this superfamily during metabolism, often termed 'cooperativity', remain to be fully elucidated. Although there is evidence that oligomerization may play an important role in defining the observed cooperativity, some monomeric cytochromes P450, particularly those involved in xenobiotic metabolism, also display this behavior due to their ability to simultaneously bind several substrate molecules. As a result, formation of distinct enzyme-substrate complexes with different stoichiometry and functional properties can give rise to homotropic and heterotropic cooperative behavior. This review aims to summarize the current understanding of cooperativity in cytochromes P450, with a focus on the nature of cooperative effects in monomeric enzymes.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, United States of America
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Isin EM, Guengerich FP. Substrate binding to cytochromes P450. Anal Bioanal Chem 2008; 392:1019-30. [PMID: 18622598 DOI: 10.1007/s00216-008-2244-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 06/10/2008] [Accepted: 06/11/2008] [Indexed: 01/08/2023]
Abstract
P450s have attracted tremendous attention owing to not only their involvement in the metabolism of drug molecules and endogenous substrates but also the unusual nature of the reaction they catalyze, namely, the oxidation of unactivated C-H bonds. The binding of substrates to P450s, which is usually viewed as the first step in the catalytic cycle, has been studied extensively via a variety of biochemical and biophysical approaches. These studies were directed towards answering different questions related to P450s, including mechanism of oxidation, substrate properties, unusual substrate oxidation kinetics, function, and active-site features. Some of the substrate binding studies extending over a period of more than 40 years of dedicated work have been summarized in this review and categorized by the techniques employed in the binding studies.
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Affiliation(s)
- Emre M Isin
- Biotransformation Section, Department of Discovery DMPK & Bioanalytical Chemistry, AstraZeneca R & D Mölndal, 431 83, Mölndal, Sweden.
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