The arrangement of substrate and organophosphorus-inhibitor leaving groups in acetylcholinesterase active site.

The leaving groups of serine esterase substrates and organophosphorus inhibitors bind to different loci at the enzyme active site. Kinetic proof of this general conclusion is presented in the case of acetylcholinesterase reactions. The proposed model for acetylcholinesterase active site provides a new stereochemical mechanism for the phosphorylated enzyme reactivation.