Acetyl choline is a neurotransmitter
substance. It is produced by one nerve cell - the presynaptic neurone - and it diffuses into the gap called the synapse
between that and the next nerve cell - the postsynaptic neurone.
When the acetyl choline reaches the postsynaptic neurone, it interacts with receptors on the membrane, which then causes the opening of sodium ion channels, thus depolarising the postsynaptic membrane and causing a potential which causes an impulse to travel on from the postsynaptic neurone.
After this, acetyl choline is broken down by an enzyme choline esterase
which breaks the (ester) linkage between the 2 parts of the molecule. Acetyl choline is later re-synthesised and stored in vesicles, ready to be released by exocytosis when another impulse is received.
Several nerve gases
act as choline esterase inhibitors and disrupt the normal passage of impulses between nerves and muscles. Interestingly, some organophosphorus insecticides operate in this way. Being many times more toxic to insects than to other organisms, such as Man, they are however not without risk.
The term acetyl has been superceded by the term ethanoyl. However there are many biochemical molecules still referred to by the old names.
On hydrolysis, acetyl choline breaks down to ethanoic (acetic) acid and choline. Choline is a quaternary saturated amine with the chemical formula