The formation of g = 2.49-species of cytochrome P450 in the rat liver by PCB126 oral administration: Identification of heme axial ligands by EPR spectroscopy

Hidetoshi Morita, Hiroshi Yoshikawa, Tatsuya Takizawa, Mitsuyuki Shirai, Fumiaki Akahori, Tetsuhiko Yoshimura

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Rat livers and microsomes were subjected to electron paramagnetic resonance (EPR) measurements at 77 K. The EPR spectra of the livers from the control group, carbon tetrachloride-, 3-methylcholanthrene-, and 3,3′,4,4′, 5-pentachlorobiphenyl (PCB126)-treated rats exhibited an EPR spectrum at g = 2.40, 2.24, and 1.93, which is characteristic of P450 in a resting state. The liver of the PCB126-treated rats showed an additional distinct EPR spectrum at g = 2.49, 2.26, and 1.87 (g = 2.49-species). The heme environmental structure of g = 2.49-species was identified by crystal field analysis using three EPR g-values of the microsome treated with various chemicals. These results indicated that g = 2.49-species is a hemeprotein with cysteine thiolate at the 5th coordination site, and a nitrogenous ligand at the 6th site.

Original languageEnglish
Pages (from-to)2974-2981
Number of pages8
JournalBioscience, Biotechnology and Biochemistry
Issue number12
Publication statusPublished - Dec 1 2006



  • 3,3′,4,4′, 5-pentachlorobiphenyl (PCB126)
  • Crystal field analysis
  • Low-spin Fe(III) hemeprotein

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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