- 著者
-
Kikuta Yasushi
Kusunose Emi
Okumoto Tsuyoshi
Kubota Ichiro
Kusunose Masamichi
- 出版者
- The Japanese Biochemical Society
- 雑誌
- The Journal of Biochemistry (ISSN:0021924X)
- 巻号頁・発行日
- vol.107, no.2, pp.280-286, 1990
Two forms of cytochrome P-450 (P-450), designated as P-450<sub>LpGAω1</sub> and P-450<sub>LpGAω2</sub>, have been purified to specific contents of 17.9 and 11.1 nmol P-450/mg protein, respectively, from liver microsomes of rabbits treated with di(2-ethylhexyl.)phthalate (DEHP), a peroxisomal proliferator. The purified P-450<sub>LpGAω1</sub> and P-450<sub>LpGAω2</sub> were found to have apparent molecular weights of 52, 500 and 53, 000, respectively. They showed absorption maxima at 451 and 450 nm in the carbon monoxide-difference spectra for their reduced forms, respectively. The two P-450s both efficiently catalyzed the ω-hydroxylation of prostaglan-dins A<sub>1</sub> (PGA<sub>1</sub>) and A<sub>2</sub> (PGA<sub>2</sub>), as well as the ω- and (ω-1)-hydroxylation of fatty acids such as laurate, myristate, and palmitate. In a reconstituted system, various metal ions such as N<sup>a+</sup> and Mg<sup>2+</sup> stimulated these reactions. The P-450s exhibited no detectable activity toward several xenobiotics tested. The two P-450s showed different peptide map patterns following limited proteolysis with <i>Staphylococcus aureus</i> V<sub>8</sub> protease or papain. The NH<sub>2</sub>-terminal amino acid sequences (ALNPTRLPGSLSGLLQVAGL and ALSLTRLPGSFS-GFLQAxGLLGLLL) of P-450<sub>LpGAω1</sub>, and P-450<sub>LpGAω2</sub> were identical at 18/20 and 19/24 positions with that of the lung prostaglandin ω-hydroxylase from pregnant rabbits, respectively. An antibody against P-450<sub>LpGAω2</sub> recognized a 52, 000-53, 000 molecular weight protein(s) in rabbit liver microsomes. The intensity of the immunoblot was significantly increased in liver microsomes from rabbits treated with DEHP, but not with phenobarbital or 3-methylcholanthrene. The laurate and PGA<sub>1</sub> ω-hydroxylase activities of liver mi-crosomes from both untreated and DEHP-treated rabbits were markedly inhibited by pretreatment with the antibody against P-450<sub>LpGAω1</sub> or P-450<sub>LpGAω2</sub>. The results suggest that the two P-450s are responsible for a major portion of the fatty acid and PGA ω-hydroxylase activities in rabbit liver microsomes. To our knowledge, this is the first time that P-450s specific for ω-hydroxylase activities have been isolated from liver microsomes of DEHP-treated rabbits.