Midge aldrin epoxidase

Midges converted 58% of absorbed aldrin to dieldrin but midge epoxidase was completely inhibited in vitro and in vivo by PBO, demonstrating that PBO is a potent inhibitor of midge MFO... 

In vitro dieldrin production increased proportionally to larval concentration (enzyme concentration) up to 5 larvae/ml and each 10X increase in substrate (aldrin) concentration tripled and doubled, respectively, dieldrin formation. An approximation of 2 X 10-5 M aldrin as the Km value for midge epoxidase was obtained from a double reciprocal plot of data in Table VII, which closely corresponds to values for aldrin epoxidase in the house fly (28) and the southern armyworm (11). 

Within expected variation, the optimum conditions for in vitro epoxidase activity of midges are typical of other insects. Maximum activity was obtained with 1 mg aldrin in 5 ml homogenate, an electron generator system with NADP, pH 7.5 buffer of 5 X 10-1 M and incubation for 15 min at 30°C. 

Midge aldrin epoxidase is highly active and may be completely inhibited ill vivo or iji vitro by PBO. 

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