Final answer:
Certain esters of trifluoromethanesulfonic acid irreversibly inhibit acetylcholinesterase by forming a stable covalent intermediate with the enzyme. This inhibits the enzyme's ability to hydrolyze acetylcholine, resulting in prolonged muscle contraction.
Step-by-step explanation:
Irreversible inhibition of acetylcholinesterase by certain esters of trifluoromethanesulfonic acid occurs through the formation of a covalent intermediate between the enzyme and the inhibitor.
The ester group of the inhibitor reacts with a nucleophile in the active site of the enzyme, resulting in the formation of a covalent bond. This covalent bond is highly stable and cannot be easily broken, which makes the inhibition irreversible.
An example of such an ester is di-isopropylfluorophosphate (DFP), which is a component of nerve gas. DFP irreversibly inhibits acetylcholinesterase and other enzymes by forming a covalent bond with the active site serine residue of the enzyme.
This prevents the enzyme from hydrolyzing acetylcholine, leading to an accumulation of acetylcholine and prolonged muscle contraction.