[gmx-users] does gromos force field can explain pi-pi interaction

[Diane Fournier]

I have read a lot on this subject since I wanted to prove one such interaction myself (between inhibitor and enzyme).

Generally, authors who talk of such interaction never give proof using simulation, but use a simple geometric criteria (benzene rings are superposed in T-shape or face-to-face staggered configuration at a given distance) to describe them in crystal structures.

For modeling, there are a few papers (beginning 1990s, not quite recent) which used a point charge model to model pi-pi stacking (Hunter-Saunders model). In this model, charges are distributed onto the hydrogens and in the middle of the benzene ring (with a dummy atom) and their results (geometry optimization) showed some similarity to experimental results seen in crystals. I can give you the references if you like.

However, pi-pi interactions have some polarization component, and so they have been best modeled with quantum mechanics; this would involve doing a QMMM simulation. I have not seen yet a paper talking about QMMM simulation of pi-pi stacking (if somebody has seen one please give me the reference)

I have also heard of polarizable force fields, but I don't know if they can model pi-stacking properly.

If somebody has heard of a proven method of modeling pi-stacking, energy- and geometry-wise, I would also be very interested in it.

Diane

   


-----Original Message-----
From: gmx-users-bounces at gromacs.org on behalf of Wei Fu
Sent: Wed 7/26/2006 11:44 AM
To: gmx-users at gromacs.org
Subject: [gmx-users] does gromos force field can explain pi-pi interaction
 
Dear gmx users,

    My simulation shows that the aromatic ring of ligand forms stacking
pi-pi interaction with the side chain of Phe of receptor during MD
simulation.
One reviewer of my manuscript questions that such pi-pi interaction can
not accurately accounted for by the employed force field.  

I do not know how to answer this question, any idea is highly appreciated!

Linda


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