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
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