[gmx-users] histidine (HISB) planarity >> how about Trp?

[Erik Lindahl]

Hi,

On Aug 15, 2006, at 9:49 AM, Berk Hess wrote:

>
> I do not think there is an error in ffG53a6.rtp for TRP.
> OPLS and GROMOS use different approaches to keep
> rings planar.
> I don't know which force field would be closest to reality.
> But I think slighlty more or less rigid rings will have little
> influence on the properties of proteins.

It's definitely worth remembering that out-of-plane torsions in most  
force fields are just rough guesses. All the digits in  
ffoplsaabon.itp are artificial - translate them to kcal and most  
impropers will be 1 or 1.1 kcal/mol, which says something about the  
accuracy.

Cheers,

Erik