[gmx-users] Running MD only for selected part of molecule

Justin A. Lemkul jalemkul at vt.edu
Sun Oct 12 13:37:44 CEST 2008



vivek sharma wrote:
> Hi Justin,
> I tried the genpr for generating the posre.itp, but it is taking only a 
> single residue while I want to restrict a number of residue for the mdrun.
> Please suggest me the way out.
> 
> Procedure followed:
> ....generated gro using pdb2gmx
> ....generated box using editconf
> ....add water using genbox
> ....make pr.index file for the residues I want to restrict for MDS (for 
> say 10 residues)
> ....tried genpr command to generate the posre.itp using pr.index 
> generated above.
> In th elast step it is generating the posre.itp for a single residue and 
> not allowing to include more residues..
> as r_26 in following response..while I want to select all of r_27,28 and 29
> 

You need to make these residues a single group.  At the make_ndx prompt, you 
need to include all the residues you want in that group: r 25-29.

-Justin

> 
> Select group to position restrain
> Group     0 (      System) has 23342 elements
> Group     1 (     Protein) has  2626 elements
> Group     2 (   Protein-H) has  2073 elements
> Group     3 (     C-alpha) has   269 elements
> Group     4 (    Backbone) has   807 elements
> Group     5 (   MainChain) has  1077 elements
> Group     6 (MainChain+Cb) has  1329 elements
> Group     7 ( MainChain+H) has  1342 elements
> Group     8 (   SideChain) has  1284 elements
> Group     9 ( SideChain-H) has   996 elements
> Group    10 ( Prot-Masses) has  2626 elements
> Group    11 ( Non-Protein) has 20716 elements
> Group    12 (         NDP) has    61 elements
> Group    13 (         SOL) has 20655 elements
> Group    14 (       Other) has 20716 elements
> Group    15 (        r_25) has     5 elements
> Group    16 (        r_26) has     9 elements
> Group    17 (        r_27) has     5 elements
> Group    18 (        r_28) has    17 elements
> Group    19 (        r_29) has    10 elements
> Select a group: pr
> Error: Multiple groups 'pr' selected
> Error: No such group 'pr'
> Select a group: 16
> Selected 16: 'r_26'
> 
> Back Off! I just backed up posre.itp to ./#posre.itp.3#
> 
> gcq#232: "These are Ideas, They are Not Lies" (Magnapop)
> _____________________________________________________________
> 
> Please suggest
> 
> With Thanks,
> Vivek
> 
> 2008/10/10 Samuel Coulbourn Flores 花山 <scflores at stanford.edu 
> <mailto:scflores at stanford.edu>>
> 
>     You might want to try Simbody (simtk.org <http://simtk.org>).  This
>     will allow you to rigidify any part or parts of the molecule you
>     choose.  As a bonus, you will not spend resources computing
>     intramolecular interactions in the rigidified regions.  
> 
>     Sam
> 
>     On Oct 10, 2008, at 6:10 AM, Justin A. Lemkul wrote:
>>
>>
>>     vivek sharma wrote:
>>>     Hi justin,
>>>     My apologies for asking you so many small queries.
>>>     Can you suggest any good tutorial or reference that talks about
>>>     this issue of running MD over a selected part of molecule.
>>
>>     If you're using PR, all you're doing is position-restrained dynamics.
>>
>>     -Justin
>>
>>>     With Thanks,
>>>     Vivek
>>>     2008/10/10 vivek sharma <viveksharma.iitb at gmail.com
>>>     <mailto:viveksharma.iitb at gmail.com>
>>>     <mailto:viveksharma.iitb at gmail.com>>
>>>        hI justin,
>>>        Thanks for your response.
>>>        do I need to specify the index file(for residue that I want to
>>>     keep
>>>        fix during MD) during GROMPP or just including the psre.itp in
>>>        topology is enough for the purpose ?
>>>        With Thanks,
>>>        Vivek
>>>        2008/10/10 Justin A. Lemkul <jalemkul at vt.edu
>>>     <mailto:jalemkul at vt.edu> <mailto:jalemkul at vt.edu>>
>>>            Justin A. Lemkul wrote:
>>>                vivek sharma wrote:
>>>                    Thanks Justin,
>>>                    My goal is to keep certain part fixed and move only a
>>>                    few of the residues (case is like providing
>>>     flexibility
>>>                    to the site of interest only).
>>>                    SO , do I need to specify the residue using some index
>>>                    file ?
>>>                    or is  there some other way to specify the part of
>>>                    molecule for position restraining ??
>>>            Make an index file with the residues you want to keep
>>>     fixed, and
>>>            pass it
>>>            to genpr to generate a new posre.itp that corresponds to those
>>>            residues.
>>>            -Justin
>>>                    With Thanks,
>>>                    Vivek
>>>                    2008/10/10 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>>>
>>>                       vivek sharma wrote:
>>>                           Hi there,
>>>                            I want to run MD over a part of my molecule ,
>>>                    for few residues
>>>                           only (not the whole molecule).
>>>                           Can I do it using GROMACS ?
>>>                           I searched for the online documentation and
>>>                    mailing list, but
>>>                           unable to get appropriate information.
>>>                           If somebody has already tried such things
>>>                    earlier, please
>>>                           suggest and direct me for appropriate link and
>>>                    address.
>>>                       Well, if your goal is to keep certain parts
>>>     fixed and
>>>                    allow others
>>>                       to move, probably the easiest way to do it is to
>>>                    apply position
>>>                       restraints to the "fixed" part.
>>>                       -Justin
>>>                           With Thanks,
>>>                           Vivek
>>>                                          ------------------------------------------------------------------------
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>>>                       --     ========================================
>>>                       Justin A. Lemkul
>>>                       Graduate Research Assistant
>>>                       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
>>>            Graduate Research Assistant
>>>            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
>>     Graduate Research Assistant
>>     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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> 
>     Samuel Coulbourn Flores, PhD
>     Altman Lab
>     Department of BioEngineering
>     Stanford University
>     samuel.flores at aya.yale.edu <mailto:samuel.flores at aya.yale.edu>
>     650.644.8416
> 
>     花山
>     科学者
>     生物工学部
>     スタンフォ一ド大学
>     スタンフォ一ド、カリフォルニア、米国
> 
> 
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-- 
========================================

Justin A. Lemkul
Graduate Research Assistant
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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