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Wang Z, Huang Q, Zhang F, Wu J, Wang L, Sun Y, Deng Y, Jiang J. Key Role of Porcine Cytochrome P450 2A19 in the Bioactivation of Aflatoxin B 1 in the Liver. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:2334-2346. [PMID: 38235998 DOI: 10.1021/acs.jafc.3c08663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
The metabolic transformation of aflatoxin B1 (AFB1) in pigs remains understudied, presenting a gap in our toxicological understanding compared with extensive human-based research. Here, we found that the main products of AFB1 in porcine liver microsomes (PLMs) were AFB1-8,9-epoxide (AFBO), the generation of which correlated strongly with the protein levels and activities of cytochrome P450 (CYP)3A and CYP2A. In addition, we found that porcine CYP2A19 can transform AFB1 into AFBO, and its metabolic activity was stronger than the other CYPs we have reported, including CYP1A2, CYP3A29, and CYP3A46. Furthermore, we stably transfected all identified CYPs in HepLi cells and found that CYP2A19 stable transfected HepLi cells showed more sensitivity in AFB1-induced DNA adducts, DNA damage, and γH2AX formation than the other three stable cell lines. Moreover, the CYP2A19 N297A mutant that lost catalytic activity toward AFB1 totally eliminated AFB1-induced AFB1-DNA adducts and γH2AX formations in CYP2A19 stable transfected HepLi cells. These results indicate that CYP2A19 mainly mediated AFB1-induced cytotoxicity through metabolizing AFB1 into a highly reactive AFBO, promoting DNA adduct formation and DNA damage, and lastly leading to cell death. This study advances the current understanding of AFB1 bioactivation in pigs and provides a promising target to reduce porcine aflatoxicosis.
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Affiliation(s)
- Zige Wang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Qiang Huang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Feiyong Zhang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Jiajun Wu
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Lingling Wang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Yu Sun
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Yiqun Deng
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Academy of Agricultural Sciences, Guangzhou 510640, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
| | - Jun Jiang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, Guangdong, P. R. China
- Key Laboratory of Zoonosis of the Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou 510642, Guangdong, P. R. China
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Ma G, Yu H, Han C, Jia Y, Wei X, Wang Z. Binding and Metabolism of Brominated Flame Retardant β-1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane in Human Microsomal P450 Enzymes: Insights from Computational Studies. Chem Res Toxicol 2020; 33:1487-1496. [DOI: 10.1021/acs.chemrestox.0c00076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Guangcai Ma
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Haiying Yu
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Cenyang Han
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Yue Jia
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Xiaoxuan Wei
- College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
| | - Zhiguo Wang
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou 311121, China
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Neves Cruz J, Santana de Oliveira M, Gomes Silva S, Pedro da Silva Souza Filho A, Santiago Pereira D, Lima E Lima AH, de Aguiar Andrade EH. Insight into the Interaction Mechanism of Nicotine, NNK, and NNN with Cytochrome P450 2A13 Based on Molecular Dynamics Simulation. J Chem Inf Model 2019; 60:766-776. [PMID: 31622091 DOI: 10.1021/acs.jcim.9b00741] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tobacco smoke contains various cancer-causing toxic substances, including nicotine and nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN). The cytochrome 2A13 is involved in nicotine metabolism and in the activation of the pro-carcinogenic agents NNK and NNN, by means of α-hydroxylation reactions. Despite the significance of cytochrome 2A13 in the biotransformation of these molecules, its conformational mechanism and the molecular basis involved in the process are not fully understood. In this study, we used molecular dynamics and principal component analysis simulations for an in-depth analysis of the essential protein motions involved in the interaction of cytochrome 2A13 with its substrates. We also evaluated the interaction of these substrates with the amino acid residues in the binding pocket of cytochrome 2A13. Furthermore, we quantified the nature of these chemical interactions from free energy calculations using the Molecular Mechanics/Generalized Born Surface Area method. The ligands remained favorably oriented toward compound I (cytochrome P450 O═FeIV state), to undergo α-hydroxylation. The hydrogen bond with asparagine 297 was essential to maintaining the substrates in a favorable catalytic orientation. The plot of first principal motion vs second principal motion revealed that the enzyme's interaction with nicotine and NNK involved different conformational subgroups, whereas the conformational subgroups in the interaction with NNN are more similar. These results provide new mechanistic insights into the mode of interaction of the substrates with the active site of cytochrome 2A13, in the presence of compound I, which is essential for α-hydroxylation.
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Affiliation(s)
- Jorddy Neves Cruz
- Adolpho Ducke Laboratory , Emílio Goeldi Paraense Museum , Belém , Pará 66040-170, Brazil.,Laboratory of Agro-Industry , Embrapa Eastern Amazon , Belém , Pará 66040-170, Brazil
| | | | - Sebastião Gomes Silva
- Adolpho Ducke Laboratory , Emílio Goeldi Paraense Museum , Belém , Pará 66040-170, Brazil
| | | | | | - Anderson Henrique Lima E Lima
- Laboratory of Planning and Development of Pharmaceuticals , Federal University of Pará , Belém , Pará 70770-901, Brazil
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Hua F, Guo Y, Sun Q, Yang L, Gao F. HapMap-based study: CYP2A13 may be a potential key metabolic enzyme gene in the carcinogenesis of lung cancer in non-smokers. Thorac Cancer 2019; 10:601-606. [PMID: 30807688 PMCID: PMC6449263 DOI: 10.1111/1759-7714.12954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 12/30/2022] Open
Abstract
Background The aim of this study was to evaluate the association between CYP2A13 polymorphisms and lung cancer susceptibility using the HapMap database. Methods A case‐control analysis of 532 subjects with lung cancer and 614 controls with no personal history of the disease was performed. The tag SNPs rs1645690 and rs8192789 for CYP2A13 were selected, and the genetic polymorphisms were confirmed experimentally through real‐time PCR, cloning, and sequencing assay. Results SNP frequency in this study was consistent with the HapMap Project database of Han‐Chinese and lung cancer risk was associated with CYP2A13 polymorphisms in non‐smokers. CYP2A13 shares a 93.5% identity with CYP2A6 in the amino acid sequence and the homologous sequences may interfere with the study of SNPs of CYP2A13. Conclusions CYP2A13 may be a potential key metabolic enzyme gene in the carcinogenesis of lung cancer in non‐smokers. The common polymorphisms of CYP2A13 may be candidate biomarkers for lung cancer susceptibility in Han‐Chinese.
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Affiliation(s)
- Feng Hua
- Department of Thoracic Surgery, Shandong Cancer Hospital Affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, China
| | - Yonglu Guo
- Department of Respiratory, Jiuquan City People's Hospital, Jiuquan, China
| | - Qiang Sun
- Department of Infection, Jiuquan City People's Hospital, Jiuquan, China
| | - Leizhou Yang
- Department of Internal Medicine, Jining City Yanzhou District Railway Hospital, Jining, China
| | - Fang Gao
- Department of Thoracic Surgery, Shandong Cancer Hospital Affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, China
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Fan T, Sun G, Zhao L, Cui X, Zhong R. Metabolic Activation and Carcinogenesis of Tobacco-Specific Nitrosamine N'-Nitrosonornicotine (NNN): A Density Function Theory and Molecular Docking Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E178. [PMID: 30634532 PMCID: PMC6352179 DOI: 10.3390/ijerph16020178] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/20/2018] [Accepted: 01/03/2019] [Indexed: 12/13/2022]
Abstract
N'-nitrosonornicotine (NNN) is one of the tobacco-specific nitrosamines (TSNAs) that exists widely in smoke and smokeless tobacco products. NNN can induce tumors in various laboratory animal models and has been identified by International Agency for Research on Cancer (IARC) as a human carcinogen. Metabolic activation of NNN is primarily initiated by cytochrome P450 enzymes (CYP450s) via 2'-hydroxylation or 5'-hydroxylation. Subsequently, the hydroxylating intermediates undergo spontaneous decomposition to generate diazohydroxides, which can be further converted to alkyldiazonium ions, followed by attacking DNA to form various DNA damages, such as pyridyloxobutyl (POB)-DNA adducts and pyridyl-N-pyrrolidinyl (py-py)-DNA adducts. If not repaired correctly, these lesions would lead to tumor formation. In the present study, we performed density functional theory (DFT) computations and molecular docking studies to understand the mechanism of metabolic activation and carcinogenesis of NNN. DFT calculations were performed to explore the 2'- or 5'- hydroxylation reaction of (R)-NNN and (S)-NNN. The results indicated that NNN catalyzed by the ferric porphyrin (Compound I, Cpd I) at the active center of CYP450 included two steps, hydrogen abstraction and rebound reactions. The free energy barriers of the 2'- and 5'-hydroxylation of NNN are 9.82/8.44 kcal/mol (R/S) and 7.99/9.19 kcal/mol (R/S), respectively, suggesting that the 2'-(S) and 5'-(R) pathways have a slight advantage. The free energy barriers of the decomposition occurred at the 2'-position and 5'-position of NNN are 18.04/18.02 kcal/mol (R/S) and 18.33/19.53 kcal/mol (R/S), respectively. Moreover, we calculated the alkylation reactions occurred at ten DNA base sites induced by the 2'-hydroxylation product of NNN, generating the free energy barriers ranging from 0.86 to 4.72 kcal/mol, which indicated that these reactions occurred easily. The docking study showed that (S)-NNN had better affinity with CYP450s than that of (R)-NNN, which was consistent with the experimental results. Overall, the combined results of the DFT calculations and the docking obtained in this study provide an insight into the understanding of the carcinogenesis of NNN and other TSNAs.
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Affiliation(s)
- Tengjiao Fan
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
| | - Guohui Sun
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
| | - Xin Cui
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental & Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
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Zhao H, He H, Shi L, Cai X, Li H, Lan M, Zhang Q. Electrochemical detection of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone using a cytochrome P450 2E1 decorated biosensor. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2018.03.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Fan JR, Li H, Zhang HX, Zheng QC. Exploring the structure characteristics and major channels of cytochrome P450 2A6, 2A13, and 2E1 with pilocarpine. Biopolymers 2018; 109:e23108. [PMID: 29484634 DOI: 10.1002/bip.23108] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 12/25/2022]
Abstract
The majority of cytochromes P450 play a critical role in metabolism of endogenous and exogenous substrates, some of its products are carcinogens. Therefore, inhibition of P450 enzymes activity can promote the detoxification and elimination of chemical carcinogens. In this study, molecular dynamics (MD) simulations and adaptive steered molecular dynamics (ASMD) simulations were performed to explore the structure features and channel dynamics of three P450 isoforms 2A6, 2A13, and 2E1 bound with the common inhibitor pilocarpine. The binding free energy results combined with the PMF calculations give a reasonable ranking of binding affinity, which are consistent with the experimental data. Our results uncover how a sequence divergence of different CYP2 enzymes causes individual variations in major channel selections. On the basis of channel bottleneck and energy decomposition analysis, we propose a gating mechanism of their respective major channels in three enzymes, which may be attributed to a reversal of Phe209 in CYP2A6/2A13, as well as the rotation of Phe116 and Phe298 in CYP2E1. The hydrophobic residues not only make strong hydrophobic interactions with inhibitor, but also act as gatekeeper to regulate the opening of channel. The present study provides important insights into the structure-function relationships of three cytochrome P450s and the molecular basis for development of potent inhibitors.
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Affiliation(s)
- Jing-Rong Fan
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Jilin University, Changchun, 130023, People's Republic of China
| | - Heng Li
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Science, Jilin University, Changchun, 130012, People's Republic of China
| | - Hong-Xing Zhang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Jilin University, Changchun, 130023, People's Republic of China
| | - Qing-Chuan Zheng
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Jilin University, Changchun, 130023, People's Republic of China.,Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Science, Jilin University, Changchun, 130012, People's Republic of China
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Uno T, Ogura C, Izumi C, Nakamura M, Yanase T, Yamazaki H, Ashida H, Kanamaru K, Yamagata H, Imaishi H. Point mutation of cytochrome P450 2A6 (a polymorphic variant CYP2A6.25) confers new substrate specificity towards flavonoids. Biopharm Drug Dispos 2015. [DOI: 10.1002/bdd.1966] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tomohide Uno
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Chika Ogura
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Chiho Izumi
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Masahiko Nakamura
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Science; Kyoto Gakuen University; 1-1 Nanjo, Sogabe Kameoka Kyoto 621-8555 Japan
| | - Takeshi Yanase
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Hiroshi Yamazaki
- Laboratory of Drug Metabolism and Pharmacokinetics; Showa Pharmaceutical University; Machida Tokyo 194-8543 Japan
| | - Hitoshi Ashida
- Laboratory of Biochemistry Frontiers, Graduate School of Agricultural Science; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Kengo Kanamaru
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Hiroshi Yamagata
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
| | - Hiromasa Imaishi
- Functional Analysis of Environmental Genes, Research Center for Environmental Genomics; Kobe University; Nada-ku Kobe Hyogo 657-8501 Japan
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Kandagatla SK, Mack T, Simpson S, Sollenberger J, Helton E, Raner GM. Inhibition of human cytochrome P450 2E1 and 2A6 by aldehydes: structure and activity relationships. Chem Biol Interact 2014; 219:195-202. [PMID: 24924949 DOI: 10.1016/j.cbi.2014.05.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/05/2014] [Accepted: 05/21/2014] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to probe active site structure and dynamics of human cytochrome P4502E1 and P4502A6 using a series of related short chain fatty aldehydes. Binding efficiency of the aldehydes was monitored via their ability to inhibit the binding and activation of the probe substrates p-nitrophenol (2E1) and coumarin (2A6). Oxidation of the aldehydes was observed in reactions with individually expressed 2E1, but not 2A6, suggesting alternate binding modes. For saturated aldehydes the optimum chain length for inhibition of 2E1 was 9 carbons (KI=7.8 ± 0.3 μM), whereas for 2A6 heptanal was most potent (KI=15.8 ± 1.1 μM). A double bond in the 2-position of the aldehyde significantly decreased the observed KI relative to the corresponding saturated compound in most cases. A clear difference in the effect of the double bond was observed between the two isoforms. With 2E1, the double bond appeared to remove steric constraints on aldehyde binding with KI values for the 5-12 carbon compounds ranging between 2.6 ± 0.1 μM and 12.8 ± 0.5 μM, whereas steric effects remained the dominant factor in the binding of the unsaturated aldehydes to 2A6 (observed KI values between 7.0 ± 0.5 μM and >1000 μM). The aldehyde function was essential for effective inhibition, as the corresponding carboxylic acids had very little effect on enzyme activity over the same range of concentrations, and branching at the 3-position of the aldehydes increased the corresponding KI value in all cases examined. The results suggest that a conjugated π-system may be a key structural determinant in the binding of these compounds to both enzymes, and may also be an important feature for the expansion of the active site volume in 2E1.
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Affiliation(s)
- Suneel K Kandagatla
- The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, Greensboro, NC, United States
| | - Todd Mack
- The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, Greensboro, NC, United States
| | - Sean Simpson
- The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, Greensboro, NC, United States
| | - Jill Sollenberger
- The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, Greensboro, NC, United States
| | - Eric Helton
- The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, Greensboro, NC, United States
| | - Gregory M Raner
- The University of North Carolina at Greensboro, Department of Chemistry and Biochemistry, Greensboro, NC, United States.
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Branstetter SA, Mercincavage M, Muscat JE. Time to first cigarette predicts 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in adolescent regular and intermittent smokers, National Health and Nutrition and Examination Survey (NHANES) 2007-10. Addiction 2014; 109:1005-12. [PMID: 24521204 PMCID: PMC4013259 DOI: 10.1111/add.12515] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 10/07/2013] [Accepted: 01/30/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND AIMS The time to first cigarette (TTFC) of the day is an indicator of nicotine intake in adults and adolescents. However, the relation between TTFC and biological markers of nicotine addiction and health risk in youths has not been well described. The current study examined whether an earlier TTFC predicts higher levels of a tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridal)-1 (NNAL), in regular and intermittent adolescent smokers and if this relation is mediated by nicotine intake (measured by cotinine) or cigarettes per day (CPD). DESIGN A cross-sectional analysis of a nationally representative subsample of adolescents. SETTING A general community sample from the 2007-08 and 2009-10 National Health and Nutrition and Examination Survey. PARTICIPANTS A total of 215 adolescents in the United States between the ages of 12 and 19 years who reported smoking at least once in the 5 days prior to data collection. MEASUREMENTS The primary outcome measure was urinary levels of NNAL. FINDINGS In both regular and intermittent smokers, earlier TTFC was associated dose-dependently with higher levels of NNAL (P < 0.03 in both cases). TTFC had an indirect effect on NNAL, mediated by nicotine intake (cotinine) in both regular [β = -0.08, standard error (SE) = 0.03, 95% confidence interval (CI) = -0.15, -0.03] and intermittent (β = -0.02, SE = 0.01, 95% CI = -0.05, -0.002) smokers. CPD was not found to be an important mediator of the relation between TTFC and NNAL. CONCLUSIONS Time between waking and the first cigarette of the day is correlated in daily and non-daily adolescent smokers with overall nicotine and therefore carcinogen intake.
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Affiliation(s)
- Steven A. Branstetter
- The Pennsylvania State University, Department of Biobehavioral Health, University Park, PA
| | - Melissa Mercincavage
- The Pennsylvania State University, Department of Biobehavioral Health, University Park, PA
| | - Joshua E. Muscat
- The Pennsylvania State University, Penn State College of Medicine, Hershey, PA
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DeVore NM, Scott EE. Nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone binding and access channel in human cytochrome P450 2A6 and 2A13 enzymes. J Biol Chem 2012; 287:26576-85. [PMID: 22700965 DOI: 10.1074/jbc.m112.372813] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Cytochromes P450 (CYP) from the 2A subfamily are known for their roles in the metabolism of nicotine, the addictive agent in tobacco, and activation of the tobacco procarcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Although both the hepatic CYP2A6 and respiratory CYP2A13 enzymes metabolize these compounds, CYP2A13 does so with much higher catalytic efficiency, but the structural basis for this has been unclear. X-ray structures of nicotine complexes with CYP2A13 (2.5 Å) and CYP2A6 (2.3 Å) yield a structural rationale for the preferential binding of nicotine to CYP2A13. Additional structures of CYP2A13 with NNK reveal either a single NNK molecule in the active site with orientations corresponding to metabolites known to form DNA adducts and initiate lung cancer (2.35 Å) or with two molecules of NNK bound (2.1 Å): one in the active site and one in a more distal staging site. Finally, in contrast to prior CYP2A structures with enclosed active sites, CYP2A13 conformations were solved that adopt both open and intermediate conformations resulting from an ∼2.5 Å movement of the F to G helices. This channel occurs in the same region where the second, distal NNK molecule is bound, suggesting that the channel may be used for ligand entry and/or exit from the active site. Altogether these structures provide multiple new snapshots of CYP2A13 conformations that assist in understanding the binding and activation of an important human carcinogen, as well as critical comparisons in the binding of nicotine, one of the most widely used and highly addictive drugs in human use.
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Affiliation(s)
- Natasha M DeVore
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, USA
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