How does nerve gas affect the synapse?
Nerve gasses tend to disrupt the working of the neurotransmitters and causes convulsion.
Nerve gasses (like sarin) disrupt the ability of the synapse to break down neurotransmitter such as acetylcholine. The enzyme which causes acetylcholine to be degraded, acetylcholinesterase, binds to the nerve gas which in turn disables the catalysing effect of the enzyme.
This means that the muscle, which had contracted under the influence of acetylcholine, cannot relax back again. This generally leads to muscle contractions, and more importantly, the inability to breathe.