Amino acids sequence and stabililty

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bartzx3

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Thanks in advance for you input....

So, alpha helices have an inherent electric dipole because we have a amino term ( + charge) and a carboxy term (- charged). The longer the helix, the stronger the dipole (fact).

Now, what I do not understand is: Why do negatively charged amino acids at the amino term stabilize the helix? Why do positively charged amino acids at the carboxyl term stabilize the helix?
 
Well, because the carboxyl is negatively charged, a positive amino acid would stabilize the charge at that end. Vice versa for the amino end.
 
Also, isolated charges are not stable. That's why whenever you have an ion, you always have to have a counterion. So when you have such a separation of charge on the amino acid, you need "counterions" to stabilize each of them. It's a simple Coulombic argument.
 
Most likely stability. Can you imagine trying to stack a bunch of magnets by their repulsing ends?

I like the word, coulombic arrangement. But search engine does not tell of any such detail.
 
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