P-45011β-dependent conversion of cortisol to cortisone, and 19-hydroxyandrostenedione to 19-oxoandrostenedione

Purified bovine adrenal P-450 11β has been shown to catalyze conversions of cortisol to cortisone (11-oxidase activity), and 19-hydroxyandrostenedione to 19-oxoandrostenedione (19-oxidase activity), in the reconstituted system consisting of NADPH, NADPH:adrenodoxin reductase, and adrenodoxin. The turnover numbers (mol of product formed/min/mol of P-450) were 1.2 for the 11-oxidase activity and 1.4 for the 19-oxidase activity. No reactions took place when any one of the electron-donating components were omitted either in the presence or in the absence of added NADP + . Likewise, rabbit antibody prepared against P-450 11β immunoprecipitated the 11-oxidase activity with concomitant loss of deoxycorticosterone 11β-hydroxylase activity.