James L. Krysan

Paraoxon inhibition of an insect egg lipase

Abstract A lipase present in an insect egg ( Diabrotica undecimpunctata howardi Barber) is sensitive to inhibition by low concentrations (approx. 10 −6 M) of diethyl- p -nitrophenyl phosphate. The inhibition occurs only in the presence of substrate; i.e. , exposure of the enzyme to inhibitor in the absence of substrate does not result in inhibition. The high sensitivity of this enzyme to the inhibitor makes it a likely target of organophosphate poisoning in those insect embryos killed before the appearance of the generally accepted target, cholinesterase.