Re: [AMBER] source leaprc.constph error

From: Jason Swails <>
Date: Thu, 16 Oct 2014 20:51:37 -0400

On Thu, Oct 16, 2014 at 8:29 PM, jinfeng liu <>

> Ok, thanks for your reply. Because I am new to Constant pH MD simulation,
> so I still have a question. The Arg residue is not titratable in Amber with
> constant pH method, so, why is that ?

​Because nobody bothered to compute the deprotonated charges or the
reference energy. Its pKa is quite a bit higher than even Lysine (by ~2 pK
units), so it is far less likely to titrate at any biologically relevant pH.

Jason M. Swails
Rutgers University
Postdoctoral Researcher
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Received on Thu Oct 16 2014 - 18:00:02 PDT
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