Functional characterization of human cytochrome P450 2E1 allelic variants: in vitro metabolism of benzene and toluene by recombinant enzymes expressed in yeast cells

被引：0
作者：
Nobumitsu Hanioka
Maki Yamamoto
Toshiko Tanaka-Kagawa
Hideto Jinno
Shizuo Narimatsu
机构：
[1] Okayama University,Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
[2] National Institute of Health Sciences,Division of Environmental Chemistry
来源：
Archives of Toxicology | 2010年 / 84卷
关键词：
Benzene; Toluene; Metabolism; Cytochrome P450 2E1 (CYP2E1); Genetic polymorphism;
D O I：
暂无
中图分类号：
学科分类号：
摘要：
Benzene and toluene are common organic solvents currently in worldwide industrial usage, which are metabolized mainly by hepatic cytochrome P450 2E1 (CYP2E1) in humans. Genetic polymorphism of CYP2E1 in 5′-flanking and coding regions has been found previously in Caucasian and Chinese populations. In this study, the effects of CYP2E1 alleles causing amino acid substitutions (CYP2E1*2, CYP2E1*3 and CYP2E1*4; wild-type, CYP2E1.1A) on benzene hydroxylation and toluene methylhydroxylation were studied using recombinant CYP2E1 enzymes of wild-type (CYP2E1.1) and variants (CYP2E1.2 having Arg76His, CYP2E1.3 having Val389Ile and CYP2E1.4 having Val179Ile) expressed in yeast cells. The Km, Vmax and CLint values of CYP2E1.1 were 10.1 mM, 9.38 pmol/min/pmol CYP and 0.99 nL/min/pmol CYP for benzene hydroxylation, and 3.97 mM, 19.9 pmol/min/pmol CYP and 5.26 nL/min/pmol CYP for toluene methylhydroxylation, respectively. The Km, Vmax and CLint values for benzene and toluene metabolism of CYP2E1.2, CYP2E1.3 and CYP2E1.4 were comparable to those of wild-type CYP2E1. These findings may mean that the polymorphic alleles of CYP2E1 causing amino acid substitutions are not directly associated with the metabolic activation of benzene and toluene. The information gained in this study should help to identify the variations in the toxicity of environmental pollutants.
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页码：363 / 371
页数：8
相关论文
共 261 条
[41]  
Iwabu H(1994)Human cytochrome P450 enzymes: a status report summarizing their reactions, substrates, inducers, and inhibitors J Pharmacol Exp Ther 270 414-423
[42]  
Jinno H(1999)Crystal structure of human cytochrome P450 2D6 Drug Metab Dispos 27 1274-1280
[43]  
Tanaka-Kagawa T(1989)High efficiency transformation of intact yeast cells using single stranded nucleic acids as a carrier Environ Health Perspect 82 23-29
[44]  
Naito S(1996)Structure of human microsomal cytochrome P450 2C8. Evidence for a peripheral fatty acid binding site Environ Health Perspect 104 1165-1171
[45]  
Shimizu T(1993)Structure of mammalian cytochrome P450 2B4 complexed with 4-(4-chlorophenyl)imidazole at 1.9-Å resolution: insight into the range of P450 conformations and the coordination of redox partner binding Environ Health Perspect 100 293-306
[46]  
Masuda K(1996)Interindividual variations in human liver cytochrome P-450 enzymes involved in the oxidation of drugs, carcinogens and toxic chemicals: studies with liver microsomes of 30 Japanese and 30 Caucasians Alcohol Clin Exp Res 20 138A-146A
[47]  
Katsu T(2000)Prediction of human liver microsomal oxidations of 7-ethoxycoumarin and chlorzoxazone with kinetic parameters of recombinant cytochrome P-450 enzymes J Clin Pharm Ther 25 165-175
[48]  
Narimatsu S(1993)Peroxidase-dependent metabolism of benzene’s phenolic metabolites and its potential role in benzene toxicity and carcinogenicity Biochem Pharmacol 46 1975-1981
[49]  
Hu Y(1996)An overview of benzene metabolism J Pharmacol Exp Ther 276 101-108
[50]  
Oscarson M(2003)The toxicology of benzene Int J Hyg Environ Health 206 149-171
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