Preparation of homogeneous NADPH-cytochrome P-450 reductase from rat liver.

NADPH-cytochrome P-450 reductase with capacity to support cytochrome P-450-dependent drug metabolism and to reduce artificial electron acceptors has been purified to apparent homogeneity by solubilization with Renex 690 and chromatography on DEAE-Sephadex, Agarose and QAE-Sephadex. The purified protein migrates as a single band on native and SDS-polyacrylamide gel electrophoresis, exhibits a minimum molecular weight of 80,000 daltons and contains 1 molecule each of FAD and FMN per 80,000 molecular weight. The specific activity for cytochrome $\text{c}$ as electron acceptor is 48.8 μmoles per min and for substrate hydroxylation of benzphetamine measured as NADPH oxidation in the presence of cytochrome P-450 and phosphatidylcholine is 2.5 μmoles per min.