PURIFICATION AND CHARACTERIZATION OF 2 FORMS OF CYTOCHROME-P-450 FROM RAT-KIDNEY CORTEX MICROSOMES

  • 1 November 1986
    • journal article
    • research article
    • Vol. 13  (5) , 749-755
Abstract
Two forms of cytochrome P-450 (P-450), designated P-450k-1 and P-450k-2, have been purified about 100-fold from rat kidney cortex microsomes. P-450k-1 and P-450k-2 had monomeric molecular weights of 51,500 and 52,000, respectively, on sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis. Absolute spectra of the oxidized forms indicate that P-450k-1 is largely in the low-spin state and partly in the high-spin state, and that P-450k-2 is essentially all in the former. The absorption maxima in reduced carbon monoxide difference spectra are at 450.5 and 451 nm with P-450k-1 and P-450k-2, respectively. The two P-450s catalyze the .omega.- and (.omega.-1)-hydroxylation of fatty acids such as caprate, laurate, myristate, and palmitate, although P-450k-1 exhibits a higher specificity activity with all fatty acids tested. In addition, P-450k-1 is capable of hydroxylating prostaglandin (PG) A1 and A2 at the .omega.-position, whereas P-450k-2 has no activity toward PGs. These activities are all stimulated by addition of cytochrome b5. The two P-450s give different peptide map patterns when partially digested with Staphylococcus aureus V8 protease or papain.