Acetylcholinesterase is a cholinergic enzyme that breaks down acetylcholine, a neurotransmitter located in the synapse between nerve and muscle cells and between two nerve cells. It is also known as AChE enzyme. Cholinergic enzymes are enzymes that synthesize, release, or alter acetylcholine. Acetylcholinesterase breaks down acetylcholine into acetic acid and choline, thereby returning nerve cells and their targets to rest after activation.