Functional characterization of human cytochrome P450 2E1 allelic variants: in vitro metabolism of benzene and toluene by recombinant enzymes expressed in yeast cells
Functional characterization of human cytochrome P450 2E1 allelic variants: in vitro metabolism of benzene and toluene by recombinant enzymes expressed in yeast cells
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DOI：
10.1007/s00204-009-0504-1
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发表时间：
2010-05-01
影响因子：
6.1
通讯作者：
Narimatsu, Shizuo
中科院分区：
文献类型：
--
作者：
Hanioka, Nobumitsu;Yamamoto, Maki;Narimatsu, Shizuo
苯和甲苯是目前世界范围内工业使用的常见有机溶剂，在人体中主要由肝细胞色素P450 2E1（CYP2E1）代谢。 CYP2E1 5'侧翼和编码区的遗传多态性先前已在白种人和中国人群中发现。在本研究中，使用野生型（CYP2E1.1）和变异体（CYP2E1.2具有Arg76His，具有Val389Ile的CYP2E1.3和具有Val179Ile的CYP2E1.4在酵母细胞中表达。苯羟基化的 CYP2E1.1 的 K (m)、V (max) 和 CL (int) 值为 10.1 mM、9.38 pmol/min/pmol CYP 和 0.99 nL/min/pmol CYP，甲苯的 K (m)、V (max) 和 CL (int) 值为 3.97 mM、19.9 pmol/min/pmol CYP 和 5.26 nL/min/pmol CYP分别为甲基羟基化。 CYP2E1.2、CYP2E1.3 和 CYP2E1.4 苯和甲苯代谢的 K (m)、V (max) 和 CL (int) 值与野生型 CYP2E1 相当。这些发现可能意味着引起氨基酸取代的CYP2E1多态性等位基因与苯和甲苯的代谢活化并不直接相关。这项研究中获得的信息应有助于确定环境污染物毒性的变化。
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 K (m), V (max) and CL (int) 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 K (m), V (max) and CL (int) 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.