acetylcholinesterase

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Diagram showing how enzymes catalyze reactions: enzymes bind to substrates, form intermediate complexes, and release products. The lower section details specific mechanisms for acetylcholinesterase, sucrose phosphorylase, and maltose phosphorylase, with labeled steps and components.

acetylcholinesterase

enzyme

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July 23, 2026

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Diagram showing how enzymes catalyze reactions: enzymes bind to substrates, form intermediate complexes, and release products. The lower section details specific mechanisms for acetylcholinesterase, sucrose phosphorylase, and maltose phosphorylase, with labeled steps and components. — The actions of enzymes Mechanisms of enzymatic action.

Acetylcholinesterase is an enzyme primarily found in cholinergic nerve endings. Its main function is to break down acetylcholine, a crucial neurotransmitter. This enzyme is also present in red blood cells, though its role there is not yet understood.1

Acetylcholine is an ester of choline and acetic acid, acting as a neurotransmitter in both the central and peripheral nervous systems. It plays a key role in the parasympathetic nervous system, influencing smooth muscle contraction, blood vessel dilation, bodily secretions, and heart rate. Acetylcholine can either stimulate or inhibit responses.2

The rapid breakdown of acetylcholine by acetylcholinesterase ensures its effects are brief. Drugs that inhibit this enzyme, known as anticholinesterases, prolong acetylcholine's presence and action. These drugs have therapeutic uses, including treating conditions like myasthenia gravis and Alzheimer disease. Some anticholinesterases are also potent insecticides or nerve agents.23

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acetylcholine
Actions and breakdown
…rapidly destroyed by the enzyme acetylcholinesterase and thus is effective only briefly. Inhibitors of the enzyme (drugs known as anticholinesterases) prolong the lifetime of acetylcholine. Such agents include physostigmine and neostigmine, which are used to help augment muscle contraction in certain gastrointestinal conditions and in myasthenia gravis. Other acetylcholinesterases have…
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…rapidly destroyed by the enzyme acetylcholinesterase and thus is effective only briefly. Inhibitors of the enzyme (drugs known as anticholinesterases) prolong the lifetime of acetylcholine. Such agents include physostigmine and neostigmine, which are used to help augment muscle contraction in certain gastrointestinal conditions and in myasthenia gravis. Other acetylcholinesterases have…
Read More

muscle
Release of acetylcholine from the nerve terminal
…broken down by the enzyme acetylcholinesterase, which is anchored in the basement membrane, or diffuses out of the primary cleft, thus preventing constant stimulation of acetylcholine receptors. Drugs that inactivate acetylcholinesterase and thereby prolong the presence of acetylcholine in the cleft can lead to repetitive firing of the muscle cell…
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…broken down by the enzyme acetylcholinesterase, which is anchored in the basement membrane, or diffuses out of the primary cleft, thus preventing constant stimulation of acetylcholine receptors. Drugs that inactivate acetylcholinesterase and thereby prolong the presence of acetylcholine in the cleft can lead to repetitive firing of the muscle cell…
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nervous system
Acetylcholine
…the enzyme for its breakdown, acetylcholinesterase, are also found in motor neuron regions of the spinal cord.
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…the enzyme for its breakdown, acetylcholinesterase, are also found in motor neuron regions of the spinal cord.
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protein
The mechanism of enzymatic action
Acetylcholinesterase is used as a specific example in the sequence described below. The two substrates (S₁ and S₂) for acetylcholinesterase are acetylcholine (i.e., B―X) and water (Y). After acetylcholine (B―X) binds to the enzyme surface, a chemical bond forms between the acetyl moiety (B) of…
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Acetylcholinesterase is used as a specific example in the sequence described below. The two substrates (S₁ and S₂) for acetylcholinesterase are acetylcholine (i.e., B―X) and water (Y). After acetylcholine (B―X) binds to the enzyme surface, a chemical bond forms between the acetyl moiety (B) of…
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drug
Drugs that affect skeletal muscle
…receptors, or (3) the enzyme acetylcholinesterase (which normally inactivates acetylcholine to terminate muscle fibre contraction).
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…receptors, or (3) the enzyme acetylcholinesterase (which normally inactivates acetylcholine to terminate muscle fibre contraction).
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poison
Morphological versus functional toxic responses
…rather, it inhibits an enzyme, acetylcholinesterase, which normally degrades acetylcholine, the neurotransmitter of the parasympathetic nervous system. Inhibition of this enzyme leads to an exaggeration of the actions of the parasympathetic nervous system, including sweating, secretion of saliva, adjustment of pupil size, and defecation. The end results are increased perspiration,…
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…rather, it inhibits an enzyme, acetylcholinesterase, which normally degrades acetylcholine, the neurotransmitter of the parasympathetic nervous system. Inhibition of this enzyme leads to an exaggeration of the actions of the parasympathetic nervous system, including sweating, secretion of saliva, adjustment of pupil size, and defecation. The end results are increased perspiration,…
Read More