Acetylcholinesterase:Anenzymethat breaks down theneurotransmitteracetylcholineat thesynaptic cleft(the space between twonervecells) so the next nerve impulse can be transmitted across the synaptic gap. Pesticides of the organophosphate and carbamate types act to paralyze and kill insects by inhibiting theiracetylcholinesterase. AbbreviatedAChE.