The enzyme that breaks down acetylcholine at the neuromuscular junction is called what?

The enzyme that breaks down acetylcholine at the neuromuscular junction is acetylcholinesterase. By rapidly hydrolyzing acetylcholine, it ends the chemical signal that tells a muscle fiber to contract.

When a motor neuron’s electrical impulse reaches its terminal, acetylcholine is released into the synaptic cleft. It binds receptors on the muscle membrane and triggers an electrical response that leads to calcium release and contraction. Acetylcholinesterase then splits acetylcholine into choline and acetate.

This rapid cleanup is essential: without it, receptors would remain stimulated and the muscle could not reset normally. Choline is taken back up by the presynaptic neuron and reused to synthesize more acetylcholine with acetyl-CoA.

Acetylcholinesterase is concentrated at neuromuscular junctions and other cholinergic synapses. It is distinct from monoamine oxidase and catechol-O-methyltransferase, which process different neurotransmitters. Organophosphate pesticides and nerve agents inhibit acetylcholinesterase, allowing acetylcholine to accumulate and potentially causing spasms, respiratory failure, and paralysis.