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

Nobumitsu Hanioka, Maki Yamamoto, Toshiko Tanaka-Kagawa, Hideto Jinno, Shizuo Narimatsu

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

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 (CYP2E12, CYP2E13 and CYP2E14; 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.

Original languageEnglish
Pages (from-to)363-371
Number of pages9
JournalArchives of Toxicology
Volume84
Issue number5
DOIs
Publication statusPublished - May 2010
Externally publishedYes

Keywords

  • Benzene
  • Cytochrome P450 2E1 (CYP2E1)
  • Genetic polymorphism
  • Metabolism
  • Toluene

ASJC Scopus subject areas

  • Toxicology
  • Health, Toxicology and Mutagenesis

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