Cholinesterase Interactions with Oximes

The phosphorylation of the serine hydroxyl group in the active site of acetylcholinesterase (AChE) inactivates this essential enzyme in neurotransmission. Oximes are reactivators of AChE phosphorylated by organophosphorus compounds (OP) including insecticides and nerve agents. The effectiveness of oxime-assisted reactivation is primarily attributed to the nucleophilic displacement rate of organophosphate, but efficiency varies with the structure of the bound organophosphate, the structure of the oxime as well as rates of several other cholinesterase's reactions. Besides reactivating cholinesterases, oximes also reversibly inhibit cholinesterases and protect them from phosphorylation by OP. In this paper, we bring an overview of in vitro native and tabun-inhibited AChE and butyrylcholinesterase interactions with oximes together with conformational analysis of the oximes to relate molecular properties to their reactivation potency.