[gmx-users] g_lie query

Justin A. Lemkul jalemkul at vt.edu
Tue Dec 28 18:33:53 CET 2010



Anirban Ghosh wrote:
> Thanks a lot Justin for the reply.
> Yes I am going through all the relevant literature on LIE.
> Actually the lie.xvg file contains the same value of -25.4 for all the 
> frames. So I am getting a straight line plot. Why is this happening? Am 
> I missing out something?
> 

If the interactions of your ligand and its receptor are stable, then there may 
be no change in the energetics.  I don't know anything about your system, so I 
can't say anything beyond that.

-Justin

> Thanks a lot again.
> 
> Anirban
> 
> 
> On Tue, Dec 28, 2010 at 6:24 PM, Justin A. Lemkul <jalemkul at vt.edu 
> <mailto:jalemkul at vt.edu>> wrote:
> 
> 
> 
>     Anirban Ghosh wrote:
> 
>         Thanks a lot Justin for the reply.
>         So I ran a simulation with my ligand in water for 1 ns and using
>         g_energy I calculated the LG-14 and Coulomb-14 values from the
>         .edr file. I supplied the average of these two values as my Elj
>         and Eqq to g_lie and I got the DGbind as -25.4. Is this the
>         correct way to do this?
> 
> 
>     Again I would ask you to not rely entirely upon my advice for this.
>      I have only examined the LIE method sparingly.  My best answer is,
>     "probably," but do read the literature on the method to be sure.
> 
> 
>         And why am I getting only a single value of DGbind for all the
>         frames captured in the .edr file?
> 
> 
>     The lie.xvg file contains the LIE values as a function of time.
>      What's printed to the screen is the average value and standard
>     deviation.
> 
>     -Justin
> 
>         Thanks a lot.
> 
>         Anirban
> 
> 
>         On Mon, Dec 27, 2010 at 11:51 PM, Justin A. Lemkul
>         <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>> wrote:
> 
> 
> 
>            Anirban Ghosh wrote:
> 
>                Thanks Justin for the reply.
>                I have through the threads about g_lie, but cannot understand
>                how to get the values for Elj and Eqq for a particular
>         ligand.
>                Like in my case for a system consisting of a beta2AR
>         protein +
>                dopamine (ligand) + POPC + water, what should be the
>         values for
>                Elj and Eqq?
> 
> 
>            To obtain these (from my limited understanding), you would
>         have to
>            run a simulation of your ligand in water, decomposing the
>         nonbonded
>            energies between the ligand and solvent into LJ and Coulombic
>            components.  Those are your values.
> 
>            I should also note that simply going through the archive to
>         inform
>            yourself about the LIE method is insufficient.  The original
>            literature, and several subsequent papers (one at least
>         within the
>            last year, IIRC), describes the accuracy of the method and
>         what it
>            needs to be properly run.
> 
>            -Justin
> 
>                Thanks a lot.
> 
>                Anirban
>                On Sat, Jul 17, 2010 at 4:56 PM, Justin A. Lemkul
>                <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>> wrote:
> 
> 
> 
>                   Anirban Ghosh wrote:
> 
>                       Hi ALL,
> 
>                       I have run a protein + ligand (dopamine)
>         simulation. Now
>                I want
>                       to calculate the free energy of binding using
>         g_lie. But
>                g_lie
>                       asks for two values: Elj and Eqq. How or from
>         where can I get
>                       these values for my ligand? Also, do I need to run a
>                simulation
>                       with only the ligand? And, is there any other way
>         (like
>                MMGBSA
>                       in Amber) to calculate the free energy for my
>         simulation? Any
>                       suggestion is welcome.
>                       Thanks a lot in advance.
> 
> 
>                   Go to the literature and understand what information is
>                needed for
>                   such a simulation, and then look into the list
>         archives and
>                you'll
>                   find dozens of threads about using g_lie.
> 
>                   -Justin
> 
> 
>                       Regards,
> 
>                       Anirban
> 
> 
>                   --     ========================================
> 
>                   Justin A. Lemkul
>                   Ph.D. Candidate
>                   ICTAS Doctoral Scholar
>                   MILES-IGERT Trainee
>                   Department of Biochemistry
>                   Virginia Tech
>                   Blacksburg, VA
>                   jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu>
>         <http://vt.edu> | (540)
> 
>                231-9080
> 
>                   http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>            --     ========================================
> 
>            Justin A. Lemkul
>            Ph.D. Candidate
>            ICTAS Doctoral Scholar
>            MILES-IGERT Trainee
>            Department of Biochemistry
>            Virginia Tech
>            Blacksburg, VA
>            jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu> | (540)
>         231-9080
>            http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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> 
>     -- 
>     ========================================
> 
>     Justin A. Lemkul
>     Ph.D. Candidate
>     ICTAS Doctoral Scholar
>     MILES-IGERT Trainee
>     Department of Biochemistry
>     Virginia Tech
>     Blacksburg, VA
>     jalemkul[at]vt.edu <http://vt.edu> | (540) 231-9080
>     http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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-- 
========================================

Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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