Chemical modification of microsomal cytochrome P450: role of lysyl residues in hydroxylation activity

Abstract
Cytochrome P450 purified from phenobarbital‐induced rat liver microsomes was acetylated at 3 lysyl residues. When reconstituted with purified NADPH‐cytochrome P450 reductase, the modified cytochrome showed full activity and substrate‐induced spectral changes with d‐benzphetamine. With 7‐ethoxycoumarin, neither enzymic activity nor binding was detected. It is concluded that the positively charged lysine residues of cytochrome P450 are important for metabolism of 7‐ethoxycoumarin by cytochrome P450.