title: 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.
abstract: 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.
authors.affiliation: School of Veterinary Medicine, Azabu University, Sagamihara. morita@azabu-u.ac.jp
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Morita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Takizawa
authors.forename: Mitsuyuki
authors.initials: M
authors.lastname: Shirai
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Akahori
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000284:Administration, Oral; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004578:Electron Spin Resonance Spectroscopy; D004790:Enzyme Induction; D005260:Female; D006418:Heme / Q000378:metabolism*; D008024:Ligands; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D008024:Ligands; D006418:Heme; D003577:Cytochrome P-450 Enzyme System