Intramolecular electrostatic interactions are common in protein structures, for 
example between i and i+4 pairs on the same face of a helix. Robert Baldwin 
(Stanford) and others did a lot of work on the contribution of intramolecular 
salt bridges to helix stabilization in model helices. If I remember correctly, 
some of his studies indicated that disrupting the ionic interaction could 
completely destabilize the helix.
Your real question is if they play a role in disordered regions. The way I 
think about this is that an intramolecular salt bridge may be able to induce 
structure in an otherwise disordered region (if the pairs are strategically 
located). Alternatively, the entropic penally of folding may be too much to pay 
for by the enthalpy gain due to such an interaction (remember solvation).

The bottom line is that the fact that it is disordered means the interaction is 
not contributing significantly.  



----- Original Message -----
From: "Xiaodi Yu" <>
Sent: Saturday, November 3, 2012 12:06:32 PM
Subject: [ccp4bb] Intra-molecular interactions

Dear All: 

I have a quick question: how common it is that electrostatic interactions are 
involved in intra-molecular interactions, particularly in intrinsically 
disordered proteins? Is this interaction specific and any example? 



Xiaodi Yu, Ph.D. 
Boston Children's Hospital & 
Dana-Farber Cancer Institute 
Harvard Medical School 
3 Blackfan 
Boston, MA 02115 

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