Final answer:
Acetylcholinesterase (AChE) is the enzyme that degrades acetylcholine within the synaptic cleft, converting it into acetyl and choline. This process is necessary for controlling muscle contractions and proper neural signaling. AChE inhibitors are also used as a treatment for Alzheimer's disease.
Step-by-step explanation:
The enzyme that breaks down acetylcholine within the synaptic cleft is called acetylcholinesterase (AChE). AChE is essential for proper neuronal transmission across a synapse because it degrades the neurotransmitter acetylcholine by hydrolysis, turning it into acetyl and choline.
This helps to prevent unwanted prolonged muscle contraction, as well as allowing the postsynaptic membrane to "reset" and be ready to receive another signal. In the synaptic cleft, acetylcholinesterase is present as a soluble enzyme, and it is not free to diffuse away from the synapse.
Once neurotransmission has occurred, the neurotransmitter must be cleared from the synaptic cleft, and the presence of AChE ensures a quick breakdown of acetylcholine.
This process is vital for the regulation of muscle contractions and neural signal transmission, which is why inhibitors of acetylcholinesterase can increase neurotransmission and are used for therapeutic purposes, such as in the treatment of Alzheimer's disease.