Hepatic metabolism of cyclodiene insecticides by constitutive forms of cytochrome P-450 from lower vertebrates

1. Multiple forms of cytochrome P-450 were separated from the hepatic microsomes of untreated male rats, pigeons (Columbia livia), razorbills (Alca torda), puffins (Fratercula arctica), and rainbow trout (Salmo gairdnerii), using anion exchange chromatography and DEAE-cellulose. 2. In some cases cytochrome P-450 forms were further purified on hydroxylapatite and carboxymethyl-sephadex columns. 3. Considerable differences in the distribution of forms between these five species were evident from elution profiles on DEAE cellulose, and on analysis of the cytochrome P-450 containing pools by SDS-PAGE. 4. The metabolism of two organochlorine compounds, aldrin and the dieldrin analogue HCE, were studied in (a) intact microsomes and (b) reconstituted systems containing cytochrome P-450, from each of the five species. 5. In spite of their close structural similarity, significant differences were found between the two substrates in the distribution of catalytic activity between the cytochrome P-450 isozymes of each species.