Studies of Cytochrome P450 Reductase from Anopheles minimus Mosquito

Anopheles minimus is a malaria vector widely distributed in Southeast Asia including Thailand. There is evidence that this mosquito has become resistant to pyrethroid insecticides due to their extensive use in malaria control. The cytochrome P450 CYP6 family has been known to play a role in pyrethroid metabolism in many insect species, and NADPH‐cytochrome P450 reductase (CPR), a membrane‐bound diflavoprotein, is the unique electron donor to these P450s. Studies of An. minimus CPR (AnCPR) are very important in understanding the role of P450s in insecticide metabolism and in developing new malaria control strategies. A cDNA encoding the entire sequence of AnCPR has been constructed. A soluble CPR protein lacking the N‐terminal membrane binding domain was expressed and purified using an affinity column. The activities for cytochrome c and K 3 Fe(CN) 6 reduction were only 15% of the corresponding values of rat CPR. Further studies showed that the loss of these activities were due to the loss of flavin cofactors. Addition of FAD could recover both activities by 2.5 fold. However, addition of FMN inhibited the activities. Further studies are in progress (GM29076; UDC/RGJ of Thailand Government).