Re: [AMBER] improper dihedral torsion parameters for fused rings on tryptophan

From: FyD <>
Date: Fri, 25 Feb 2011 21:18:06 +0100

Dear Sydney,

I wonder if the following rule was not applied in the past:
A sp2 center has an oop _if_ it does _not_ bear a hydrogen/it bears a
heavy atom...

regards, Francois

> When I had "verbosity 2" set in tleap, I noticed some warnings when building
> the improper torsion parameters, see below:
> ---- snip ----
> Building improper torsion parameters.
> ** Warning: No sp2 improper torsion term for NA-CA-CN-CB
> atoms are: NE1 CZ2 CE2 CD2
> ** Warning: No sp2 improper torsion term for C*-CN-CB-CA
> atoms are: CG CE2 CD2 CE3
> ---- snip ----
> These happen to be the impropers for the fused rings on tryptophan. Is this
> correct? I have built other molecules where I include these improper angles
> on the fused rings; should I remove them? Thanks for your help.
> Sid

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Received on Fri Feb 25 2011 - 12:30:04 PST
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