Purfication and Characterization of Two Forms of 2, 3, 4, 7, 8-Pentachlorodibenzofuran-Inducible Cytochrome P-450 in Hamster Liver1

Abstract

Two forms of cytochrome P-450 (P-450) from liver microsomes of hamsters treated with 2,3,4,7,8-pentachlorodibenzofuran (PenCDF), which possesses the potent acute toxicity and 3-methylcholanthrene (MC)-type inducing ability of liver microsomal monooxygenases in animals, were purified and characterized. These P-450 forms, designated as hamster P-450H and hamster P-450L, had the molecular masses of 52 and 50 kDa, respectively, and showed the absorption maximum of CO-reduced difference spectra at 446 nm. The absolute spectra of their oxidized forms indicated that hamster P-450H was in high-spin state and hamster P-450L was in low-spin state. A part of PenCDF injected into hamster was tightly bound to purified hamster P-450H at a ratio of 0.107 nmol PenCDF/nmol P-450. In a reconstituted system, both hamster P-450H and hamster P-450L showed relatively low catalytic activities for 3-hydroxylation of benzo[a]pyrene and O-deethylations of both 7-ethoxyresorufin and 7-ethoxycoumarin, while they both catalyzed 7 alpha- and 2 alpha-hydroxylations of testosterone effectively to a similar extent. Addition of cytochrome b5-to a reconstituted system accelerated the formation of 7 alpha-hydroxytestosterone 5.3-fold with hamster P-450L and 2.2-fold with hamster P-450H. In addition, hamster P-450H catalyzed estradiol 2-hydroxylation at a high rate but hamster P-450L did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Related Papers

• → The Copper-Enzyme Family of Dopamine β-Monooxygenase and Peptidylglycine α-Hydroxylating Monooxygenase: Resolving the Chemical Pathway for Substrate Hydroxylation(2005)378 cited
• → Filamentous Fungi Potentially Useful Catalysts for the Biohydroxylations of Non-Activated Carbon Centers(2001)53 cited
• → Humoral and cellular response to infection withEchinostoma revolutumin the golden hamster,Mesocricetus auratus(1988)17 cited
• → Hydroxylation of para-chlorotoluene by model complexes of cytochrome P-450(1984)3 cited
• → EVIDENCE FOR DIFFERENT HEPATIC MONOOXYGENASES IN (ω-1)- AND ω-HYDROXYLATION OF PROSTAGLANDINS(1980)