Action of carbon tetrachloride in the reconstituted monooxygenase system using partially purified cytochrome P-450 and P-448.

In the cytochrome P-450-reconstituted system, CCl4 stimulated NADPH-dependent lipid peroxidation of the system containing the P-450 form to a much greater extent than that of the system containing the P-448 form. When the P-450-reconstituted system was preincubated in the presence of both NADPH and CCl4, 7-ethoxycoumarin O-deethylase, aminopyrine N-demethylase and aniline hydroxylase activities were decreased by 40-60%, whereas, with P-448 form reconstituted system, no suppression was observed in these enzyme activities or in 7-ethoxyresorufin O-deethylase activity. These observations suggest that the P-450 form, but not the P-448 form, is active in metabolizing CCl4 to a reactive species that subsequently impairs the hemoprotein.