Peptide planarity Dihedral angle restraints

From: Vijay Vammi (
Date: Thu Dec 08 2011 - 20:07:12 CST

Hello all,

During MD simulation, I want to put additional restraints to maintain
peptide planarity.
In AMBER forcefields, i was able to do it by increasing the Kchi value for
X-C-N-X. (in the parm99.dat).

In CHARMM forcefields, as far as I know, wildcards would be accepted only
if there is no specific combination found. One way of solving this would be
1). For every peptide bond, find all the atomtypes combination(eg:
CA-C-N-CA could be CT1-C-N-CT1 and many other possibilities) and increase
the Kchi value in the parameter file.

Is there any other simple way?

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