Evidence for a new physiological role of hepatic NADPH:ferricytochrome (P-450) oxidoreductase. Direct electron input to the microsomal fatty acid chain elongation system.

Rat hepatic cytochrome bs and NADPH-cytochrome P-450 reductase were purified to homogeneity and were used to raise rabbit anti-rat antibodies.The IgG fractions obtained from preimmune and antisera were employed to investigate the role of NADPH-cytochrome P-450 reductase and cytochrome b5 in the microsomal elongation of fatty acids.In the presence of anti-NADPH-cytochrome P-450 reductase IgG (7 mg/mg of microsomal protein), malonyl-CoA incorporation into palmitoyl-CoA was inhibited by more than SO%, as was NADPH-cytochrome c reductase activity.The antibody had no effect on the initial condensation reaction.