Resolution and reconstitution of the NADPH-cytochrome c (P-450) reductase induced by progesterone in Rhizopus nigricans.

The NADPH-cytochrome c (P-450) reductase induced in the filamentous fungus Rhizopus nigricans as a component of 11 alpha-hydroxylase of progesterone was resolved by DEAE-cellulose chromatography into two components. One of the components is an iron-sulfur protein (rhizoporedoxin), whereas the other component is a protein with reductase activity dependent on NADPH (rhizoporedoxin reductase). As shown in the reconstitution assay, the NADPH-cytochrome c (P-450) reductase activity was restored upon combination of these two proteins.