Amino acids sequence and stabililty

[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?

 

[mcatjelly]

Well, because the carboxyl is negatively charged, a positive amino acid would stabilize the charge at that end. Vice versa for the amino end.

 

[chemist16]

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.

 

[kingtal0n]

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.