Selective inactivation of NADPH-cytochrome P-450 ( c) reductase by diazotized 3-aminopyridine adenine dinucleotide phosphate

Abstract

3-Aminopyridine adenine dinucleotide phosphate was found to be a potent competitive inhibitor of NADPH-cytochrome P-450 ( c) reductase. The reductase was rapidly and irreversibly inactivated at pH 7 and 4 °C by diazotized 3-aminopyridine adenine dinucleotide phosphate. However, inactivation required the prereduction of the enzyme by NADPH. Spectral studies were consistent with the incorporation of 0.52 mol of nucleotide per mole of flavin or 1.04 mol per mole of enzyme.