Oximes are drugs known for their ability to reverse the binding of organophosphorus compounds to the enzyme acetylcholinesterase (AChE).

[1] AChE is an enzyme that removes acetylcholine from the synapse after it creates the required stimulation on the next nerve cell.

They bind to a specific place on the enzyme and prevent it from functioning normally by changing the OH group on the serine residue and by protonating (quaternary nitrogen, R4N+) the nearby nitrogen atom located in the histidine residue.

They have greater affinity for the organic phosphate residue than the enzyme and they remove the phosphate group, restore the OH to serine and turn nitrogen from histidine back into its R3N form (tertiary nitrogen).

This results in full enzyme recovery and the phosphate-oxime compound is eliminated from the organism via urine.