Which enzyme is primarily responsible for degrading acetylcholine in the synaptic cleft after neurotransmission?

• A. Catechol-O-methyltransferase
• B. Monoamine oxidase
• C. Acetylcholinesterase
• D. Choline acetyltransferase

Answer: (C)

Verified step by step guidance

1. Understand the role of acetylcholine in neurotransmission: Acetylcholine is a neurotransmitter released into the synaptic cleft to transmit signals between neurons or from neurons to muscles.
2. Identify the need for acetylcholine degradation: After acetylcholine has transmitted its signal, it must be rapidly broken down to terminate the signal and allow the synapse to reset for the next transmission.
3. Review the enzymes listed and their functions: Catechol-O-methyltransferase (COMT) and Monoamine oxidase (MAO) are enzymes that degrade catecholamines and monoamines, respectively, not acetylcholine. Choline acetyltransferase synthesizes acetylcholine rather than degrading it.
4. Recognize that acetylcholinesterase is the enzyme responsible for breaking down acetylcholine in the synaptic cleft by hydrolyzing it into acetate and choline, thus terminating the neurotransmitter's action.
5. Conclude that acetylcholinesterase is the primary enzyme responsible for degrading acetylcholine after neurotransmission.