ADRENAL GLAND STEROID C-21 CYTOCHROME P-450 REDUCTASE

The adrenal gland mitochondrial cytochrome P-450 reductase system (adrenal flavoprotein and adrenodoxin) is shown in this investigation to enhance steroid 21 hydroxylation in carefully prepared microsomal suspensions and acetone powder extracts. Examination of the reductase components separately reveals that the enhancement can be accounted for on the basis of the flavoprotein moiety alone. This implicates flavoprotein as an electron carrier in steroid 21 hydroxylation. While it seems likely that the mitochondrial and microsomal flavoproteins are identical, there remains a possibility that different, yet compatible, species may exist for the two organelles. The current studies indicate that adrenodoxin is inhibitory to microsomal 21 hydroxylation. This suggests that, either steroid 11β hydroxylation occurs at a different electron potential level than 21 hydroxylation, or that adrenodoxin relates to enzyme specificity factors of 11β hydroxylation as well as electron supply. Consistent with these evaluations is the observation that methodology, which resolves relatively large quantities of adrenodoxin from adrenal gland mitochondria, gives rise to only insignificant quantities of this entity when employed with adrenal gland microsomes. It is concluded that appropriately prepared adrenal microsomes are essentially lacking in adrenodoxin. © 1969, American Chemical Society. All rights reserved.