Properties of Acetylcholine Esterases from the Bee, the Fly and the Mouse and Their Relation to Insecticide Action

Abstract

Distinct biochemical differences in the specific cholinesterases from the brains of the 3 animals are reflected in (a) the relative anticholinesterase activity of organic phosphate compounds containing isopropoxy groups or aromatic rings or both, or thiosphos-phoryl groups; (b) in the anticholinesterase activity of various carbamic acid esters; and (c) in the relative kinetics of cholin-esterase behavior toward substrates such as acetyl beta-methyl choline. The relative differences in anticholinesterase activity of organic phosphate compounds largely determine the acute toxicities of the compounds to the organisms studied. The cholinesterase content of fly brains is extremely high, and is about equal to that reported in the electric organs of several eels. A detailed knowledge of the properties of various cholinesterases and a correlation of the structure of various organic phosphate anticholinesterases with their specific action may result in the development of insecticides with a greater margin of safety to warm-blooded animals than those currently in use, and may enable the entomologist to select compounds toxic to certain insect pests, but relatively harmless to beneficial parasites and predators.