Purification and Characterization of a Cytochrome P450 Enzyme from Pig Liver, Catalyzing the Phenol Oxidative Coupling of (R)-Reticuline to Salutaridine, the Critical Step in Morphine Biosynthesis

The cytochrome P450 enzyme catalyzing the conversion of (R)-reticuline to salutaridine in the presence of cytochrome c reductase, NADPH and 02 was purified to homogeneity from pig liver and shown to be a highly regio-and stereoselective enzyme.This finding supports the view that the occurrence of morphine in mammals is of endogenous and not of dietary origin.