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This is a proton channel of a flu virus. For a flu virus to perform infection, it must “understand” that it is located inside...
... of a human cell, and this is where this protein comes into play. Human cells contain a lot of protons, so when they are...
... transferred through this proton channel they tell the virus that it can replicate, which causes...
... a condition we all know as flu.
The way this protein works can be understood if we look from the top of the channel.
You can see that it forms a pore that is so small that only a proton can go through.
It looks like there is plenty of space, but if we show all the atoms you can see that it is very congested in the center.
This is the tightest part of the pore, just two angstroms, two millionths of a centimeter wide.
The proton channel is a target of this drug, called amantadine.
It is a very simple molecule as far as pharmaceuticals are concerned, yet it is very effective.
The drug goes right in the center of a protein pore, thus preventing protons from coming through.
In the absence of amantadine the pore is free, and a proton can go through easily.
On the other hand, when amantadine is present, a proton will be able to reach only this part of the pore...
... as it has nowhere to go.
The reason why amantadine binds to the proton channel is one of the amino acids, called serine, which is shown in red.
Unfortunately, numerous viral strains have evolved that have different amino acids in that position.
The drug is therefore unable to bind, the protons can go through and the virus is free to replicate.
This is one of the challenges to pharmaceutical industry: development of the drugs...
... that will be efficient against the mutant viruses.