[AMBER] Modeling cis-amide bonds in diketopiperazines

From: Christian Schafmeister <drschafmeister.gmail.com>
Date: Mon, 14 Mar 2022 11:03:20 -0400

Hi folks,

When I try to model diketopiperazine groups with cis secondary amide bonds
in six-member rings using GAFF they get distorted because GAFF appears to
force them to a trans geometry.
I've tried GAFF2 but it assigns the amide nitrogen type 'ns' and that is
missing all bond, angle and dihedral angles in the GAFF2 forcefield.
Otherwise GAFF2 looks fine.

Does anyone have a frcmod file that would add the missing parameters for
'ns' for GAFF2?

Best,

.Chris.
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Received on Mon Mar 14 2022 - 08:30:02 PDT
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