AChE (Acetylcholinesterase)
Definition
The enzyme that terminates cholinergic nerve impulses by hydrolysing acetylcholine. Irreversibly phosphorylated at Ser203 by OP nerve agents, causing accumulation of acetylcholine at synapses and neuroeffector junctions, leading to convulsions and respiratory failure.
- Function
- Terminates cholinergic nerve impulses
- Phosphorylation site
- Active-site serine (around Ser203)
- Inhibitor type
- OP nerve agents
- Consequence
- Convulsions, respiratory failure
- Field
- Chemical warfare agent toxicology
Common questions
Why is the phosphorylation by nerve agents described as irreversible?+
Once phosphorylated, the enzyme-agent bond can age by losing an alkyl group, after which even oxime antidotes can no longer reactivate the enzyme, making early treatment time-critical.
How does this differ from the pesticide organophosphate mechanism?+
The underlying enzyme chemistry is the same, but nerve agents are far more potent and act faster, and military or CBRN response protocols differ from civilian pesticide poisoning management.
Why is respiratory failure the immediate clinical concern in this toxidrome?+
It is usually the proximate cause of death from nerve agent exposure, driven by bronchoconstriction, secretions, and paralysis of respiratory muscles, so airway management is the treatment priority.
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