[Effect of different inactivating agents on microsomal cytochromes P-450 and P-448]

The properties of tert-butanol, sodium deoxycholate, guanidine and mersalyl to convert microsomal cytochromes P-450 and P-448 into enzymatically inactive form P-420 were studied under comparable conditions. Phenobarbital-induced cytochrome P-450 was especially sensitive to the influence of all the agents studied, while cytochrome P-450 from untreated animals was the least sensitive; the 3-methyl-cholanthrene-induced cytochrome P-448 exhibited the least sensitivity to guanidine. The dynamics of changes in content of active and inactive hemoprotein forms after in vitro treatment with the suitable agent might serve as a criterion for estimation whether the phospholipid or protein component of microsomal membrane was damaged.