Zonal distribution of cytochrome P-450s (P-450(11) beta and P-450scc) and their relation to steroidogenesis in bovine adrenal cortex.
Zona glomerulosa and zonae fasciculata-reticularis of bovine adrenal cortex were separated by our improved method using a remodeled microtome. A considerable amount of fresh mitochondria and microsomes was quickly obtained. Specific content of cytochrome P-450 in the mitochondria was higher in zonae fasciculata-reticularis than in zona glomerulosa. When metyrapone was added to the mitochondria and the drug-induced difference spectra were measured, there appeared two phases in the titration curve; the first phase was saturated at a concentration of 3 microM and the second phase appeared at concentrations higher than 10 microM. The first phase seemed to be due to the substrate-free P-450(11) beta and the second phase to the cholesterol-bound P-450scc. From these spectral studies contents of cytochrome P-450scc and P-450(11) beta were estimated, and those were found to be equal for each zone. From similar studies on substrate-induced difference spectra, there seemed to be no difference between two zones in the affinity of cytochrome P-450(11) beta for deoxycorticosterone and 11-deoxycortisol. This was also the case with 11 beta-hydroxylase activity and substrate specificity for deoxycorticosterone and 11-deoxycortisol.
D000302:Adrenal Cortex / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism; D000305:Adrenal Cortex Hormones / Q000096:biosynthesis*; D000818:Animals; D002417:Cattle; D002784:Cholesterol / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis* / Q000378:metabolism; D004579:Electron Transport; D008797:Metyrapone / Q000494:pharmacology; D008861:Microsomes / Q000032:analysis; D008928:Mitochondria / Q000032:analysis; D013053:Spectrophotometry; D013252:Steroid 11-beta-Hydroxylase / Q000378:metabolism; D013379:Substrate Specificity; D014018:Tissue Distribution
D000305:Adrenal Cortex Hormones; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol; D013252:Steroid 11-beta-Hydroxylase; D008797:Metyrapone