[gmx-users] enegry minimisation

Gaurav Goel gauravgoeluta at gmail.com
Wed May 19 15:29:33 CEST 2010


On Wed, May 19, 2010 at 9:18 AM, Justin A. Lemkul <jalemkul at vt.edu> wrote:
>
>
> Gaurav Goel wrote:
>>
>> After adding water you can do energy minimization (EM) in two steps:
>>
>> 1. Constrain the protein backbone and do EM.
>> 2. Now do EM on the full system.
>> 3. Run a short MD simulation by constraining the protein backbone.
>> The above three steps will help hydrate the protein molecule with minimal
>> distortion of protein structure.
>>
>
> Such finesse may certainly be beneficial.  Just for clarity, though, what
> you are referring to is the application of (position) restraints, not
> constraints.
>
> http://www.gromacs.org/Documentation/Terminology/Constraints_and_Restraints
>
Justin, thanks for clarifying. I was referring to position restraints.
-Gaurav
> -Justin
>
>> 4. Now run a MD on full system.
>>
>> for details looks here:
>>
>> http://www.google.com/url?sa=t&source=web&ct=res&cd=2&ved=0CBcQFjAB&url=http%3A%2F%2Feugen.leitl.org%2Fchem%2Fkerrigje%2Fpdf_files%2Ffwspidr_tutor.pdf&ei=jOPzS8a3Lab2MdX1_aAO&usg=AFQjCNGB_3mXSQRHuqehBSHXsRyXP1Gymg&sig2=bY3NqXHmruR7eSLVyAuCHQ
>> <http://www.google.com/url?sa=t&source=web&ct=res&cd=2&ved=0CBcQFjAB&url=http%3A%2F%2Feugen.leitl.org%2Fchem%2Fkerrigje%2Fpdf_files%2Ffwspidr_tutor.pdf&ei=jOPzS8a3Lab2MdX1_aAO&usg=AFQjCNGB_3mXSQRHuqehBSHXsRyXP1Gymg&sig2=bY3NqXHmruR7eSLVyAuCHQ>
>>
>> -Gaurav
>>
>> On Wed, May 19, 2010 at 8:18 AM, sonali dhindwal
>> <sonali11dhindwal at yahoo.co.in <mailto:sonali11dhindwal at yahoo.co.in>> wrote:
>>
>>    Sorry, but I couldnt get your question,
>>    I have used this .mdp file for energy minimisation after addition of
>>    water and using
>>
>>    GROMOS96 43a1 force field :
>>
>>
>>    title            = drg_trp
>>    cpp              = /lib/cpp ; location of cpp on SGI
>>    define           = -DFLEX_SPC ; Use Ferguson’s Flexible water model [4]
>>    constraints      = none
>>    integrator       = steep
>>    dt               = 0.002    ; ps !
>>    nsteps           = 2000
>>    nstlist          = 10
>>    ns_type          = grid
>>    rlist            = 0.9
>>    coulombtype      = PME ; Use particle-mesh ewald
>>    rcoulomb         = 0.9
>>    rvdw             = 1.0
>>    fourierspacing   = 0.12
>>    fourier_nx     =  0
>>    fourier_ny     =  0
>>    fourier_nz     =  0
>>    pme_order      =  4
>>    ewald_rtol     =  1e-5
>>    optimize_fft      = yes
>>    ;
>>    ;       Energy minimizing stuff
>>    ;
>>    emtol               = 1000.0
>>    emstep              = 0.01
>>
>>    I hope it will help you to guide me further
>>    Thanks
>>    --
>>    Sonali Dhindwal
>>
>>
>>    --- On *Wed, 19/5/10, Erik Marklund /<erikm at xray.bmc.uu.se
>>    <mailto:erikm at xray.bmc.uu.se>>/* wrote:
>>
>>
>>        From: Erik Marklund <erikm at xray.bmc.uu.se
>>        <mailto:erikm at xray.bmc.uu.se>>
>>        Subject: Re: [gmx-users] enegry minimisation
>>        To: "Discussion list for GROMACS users" <gmx-users at gromacs.org
>>        <mailto:gmx-users at gromacs.org>>
>>        Date: Wednesday, 19 May, 2010, 5:31 PM
>>
>>
>>        sonali dhindwal skrev:
>>         > Hello All
>>         > This question may sound trivial to many, but as i am new to
>>        this field, please help.
>>         > I want to ask a question regarding my previous query of
>>        distortion of protein strucutre after molecular dynamcs simulation.
>>         > I have noticed that after enegry minimisation using steepest
>>        decent algorithm, using emtol of 1000 kJ mol^-1 nm^-1 , large
>>        amount of distortion occurs.
>>         > So is it necessary to do enegry minimisation step before MD,
>>        because this is my modeled protein, and i have  already done
>>        energy minimisation using different program and after that I
>>        have done refinement also.
>>         > Thanks and regards
>>         > ^
>>         >
>>         >
>>         > --
>>         > Sonali Dhindwal
>>         >
>>         >
>>        So how has your system setup changed since your previous EM?
>>        Addition of water? Cutoffs? PME?
>>
>>        -- -----------------------------------------------
>>        Erik Marklund, PhD student
>>        Dept. of Cell and Molecular Biology, Uppsala University.
>>        Husargatan 3, Box 596,    75124 Uppsala, Sweden
>>        phone:    +46 18 471 4537        fax: +46 18 511 755
>>        erikm at xray.bmc.uu.se
>>        <http://mc/compose?to=erikm@xray.bmc.uu.se>
>> http://folding.bmc.uu.se/
>>
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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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