Use of 2-allyl-2-isopropylacetamide as a catalytic site probe for rabbit cytochrome P-450.

The porphyrinogenic agent, 2-allyl-2 isopropylacetamide (AIA was used as a catalytic site-specific probe for the inducible forms of rat and rabbit cytochrome P-450. The loss of specific enzyme activities associated with forms 2, 4 and 6 of rabbit liver microsomal cytochromes P-450 clearly showed that AIA not only inhibits the benzphetamine N-demethylase activity of form 2 (the major form induced by phenobarbital) but also the 7-ethoxyresorufin O-deethylase activity of form 4 (the major form induced by 2, 3, 7, 8 tetrachlorodibenzo-p-dioxin, TCDD). AIA does not appear to react directly with either form 4 or form 6 but requires prior activation by the action of at least one component of PB-microsomes, probably the form 2 cytochrome P-450, before interacting with the form 4 cytochrome.