I was reading about the [Novichok agent](https://www.reddit.com/r/wallstreetbets/comments/kbyxet/a_little_wordplay/?utm_source=share&utm_medium=web2x&context=3) and I’d like to know more about how it works along with other nerve agents without the complicated science jargon.
In: Biology
The term nerve agent is actually kinda broad. To be a nerve agent the chemical has to modify the normal function of your nerves in a way to be lethal. Some stop nerves from signaling others make them fire non stop. Others make it so they can’t receive signals.
There are several kinds of poisons that are referred to as nerve agents, but Novichok works by essentially overriding the functions in your brain that would normally run the muscles that operate things like breathing and heart function. This basically makes them seize up, which as you can imagine is not good for you.
At the cellular level our nerves represent little spaced out post offices, relaying messages from the brain to the body using neurotransmitter chemicals.
One of these chemicals is called acetylcholine. When the brain wants to move a muscle, it sends a message by triggering th first nerve to fire off acetylcholine. The acetylcholine travels across the gap to the next nerve, where it binds and causes that nerve to do the same nerve, and so on until the muscle receives the signal at the other end.
However after the signal is sent on to the next nerve, the body needs to get rid of that acetylcholine thats sitting there bound to the nerve, otherwise the nerve wouldn’t turn off. It uses an enzyme called acetylcholinesterase for this function, which zips in and chomps up that acetylcholine and recycles it for the next time it’s needed.
Nerve agents work by blocking acetylcholinesterase, so those acetylcholine molecules don’t get broken down and the nerve tracts the brain uses to control the body become jammed with signals as nerves become overloaded and paralyzed by acetylcholine.
Novichok agents belong to a class of compounds called Organophosphates. In general these contain a phosphorous atom bound to at least one carbon atom and generally 2 oxygen atoms.
Nerve agents are usually classified as being toxins that act on the neurotransmitter acetylcholine. (This includes those in organophosphate class and some other chemistries.)
Acetylcholine is the chief neurotransmitter the motor nerves use to activate muscles. Motor nerves release acetylcholine which binds to gated ion channel proteins in muscles which releases calcium ions. This triggers muscles to contract.
By disrupting the acetylcholine system, these cause difficulty with muscle control, spasms paralysis, particularly breathing muscles, and life threatening heart arrhythmia.
When the nerves stop firing, leftover acetylcholine is broken down and cleared from the junction between nerves and muscles by a group of enzymes called Cholinesterases. These are some of the most rapid acting enzymes known in the body, one of these enzymes can potentially break down several hundred acetylcholine molecules per second.
Novichok agents, along with most nerve agents, can cause a permanent structural change to the folding of the Cholinesterase enzyme, which irreversibly inhibits it. This means it stops it from being able to bind with acetylcholine. One molecule of a Novichok or other nerve agent can deactivate many Cholinesterase proteins. Potentially thousands. This explains their extreme toxicity.
This causes acetylcholine to build up in the the junction and eventually build up in the bloodstream in general, causing muscles to act abnormally. Eventually muscles stop being able to respond to nerve signals completely, resulting in paralysis and many other symptoms.
Aside from chemical weapons, a number of insecticides belong to the organophosphate class. Cholinesterases in insects have a significantly different structure than in vertebrates. Such insecticides have a different chemistry and are far, far more toxic to insects than to vertebrates. But they are still somewhat toxic, and can cause symptoms of nerve agent poisoning in large exposures on humans.
Some of the first chemical weapons were originally developed as pesticides or rodenticides. In the 1800, one of the first pesticides developed was phosphine gas (PH4.) This acts in the same way by irreversibly deactivating Cholinesterase. It was used as a fumigant to kill rodents and insects Luke bedbugs. Because it is is rapidly oxidized in air into phosphoric acid in a matter of an hour or two, its still used sometimes in the present day. Windows and vents in a building are sealed and the phosphine is generated with a chemical reaction. Once the reaction is finished, the phosphine breaks down in air and the building is safe to enter after a few hours.
Latest Answers