Chemical modification of cholesterol-hydroxylating cytochrome P450 from bovine adrenal cortex mitochondria by acetylimidazole

The state and role of tyrosine residues in adrenocortical cytochrome P-450scc was investigated. Spectrophotometric titration experiments showed the existence of two types of tyrosine residues in the hemoprotein molecule, i.e., exposed (pK 9.25) and buried (pK 10.75) ones. Chemical modification of the exposed tyrosine residues with N-acetylimidazole was carried out. The data obtained indicate the involvement of these residues in the interaction with adrenodoxin.