Anti-P450Ipr antiserum inhibits the activation of chlorpyrifos to chlorpyrifos oxon in house fly microsomes
1993
Hatano, R. | Scott, J.G.
Cytochrome P450lpr is a house fly-specific P450 that is developmentally regulated and expressed at higher levels in the insecticide resistant LPR strain compared to susceptible strains. P450lpr catalyzes the metabolism of deltamethrin, methoxyresorufin, and benzo[a]pyrene in LPR microsomes. Herein, we report on the role of cytochrome P450lpr in the metabolism of chlorpyrifos and chlorpyrifos oxon. Monooxygenase-mediated oxidative desulfuration of chlorpyrifos in the LPR strain was greater than that in the susceptible S+ strain. Anti-p450lpr antiserum caused complete inhibition of monooxygenase-mediated chlorpyrifos metabolism in S+ and nearly complete inhibition in LPR microsomes. This suggests that P450lpr is the major P450 responsible for chlorpyrifos activation and metabolism in S+ and LPR microsomes. When chlorpyrifos oxon was used as the substrate, the microsomal monooxygenases caused a significant conversion of oxon to water-soluble metabolites in both S+ and LPR microsomes; however, anti-P450lpr antiserum had no significant effect on the amount of chlorpyrifos oxon remaining in S+ and only slightly inhibited this reaction in LPR. This suggests that P450lpr is the major P450 responsible for oxidative desulfuration of chlorpyrifos, but not a major P450 involved in monooxygenase-mediated chlorpyrifos oxon metabolism. The role of P450lpr in the production of specific metabolites is discussed.
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