[gmx-users] Arginine_Hydrochloride topology

Justin A. Lemkul jalemkul at vt.edu
Fri Aug 12 14:08:58 CEST 2011



shahid nayeem wrote:
> I tried with single Arginine molecule pdb.
> pdb2gmx -f arg.pdb -o arg.gro -p arg.top
> genconf -f arg.gro -nbox 2 2 2 -o seq.gro
> genbox -cp seq.gro -cs spc216.gro -ci protein.pdb -nmol 1 -o seq_box.gro 
> -box 1.8 1.8 1.8 
> command runs but it does not add protein.pdb to the box

What is in protein.pdb?  I don't believe genbox can handle multi-residue 
molecules, but I could be wrong.  Or there could be insufficient space, which is 
quite likely.  A 1.8-nm box is too small for all but the tiniest proteins.  The 
better approach:

1. Run pdb2gmx on protein.pdb
2. Run pdb2gmx on arg.pdb, convert the .top to .itp and #include it in the .top 
from (1)
3. Run genbox -ci to add arg.gro molecules into the system

-Justin

> shahid nayeem
> 
> On Fri, Aug 12, 2011 at 4:32 PM, Justin A. Lemkul <jalemkul at vt.edu 
> <mailto:jalemkul at vt.edu>> wrote:
> 
> 
> 
>     shahid nayeem wrote:
> 
>         I couldn't get you. Does it means that  for pre-positioning say
>         40 molecules of Arginine do I need to create 40 pdb of different
>         coordinate then combine it with pdb of protein and then use
>         pdb2gmx. I want to use different number of free positively
>         charged Arginine molecule in simulation box along with protein.
>         shahid nayeem
> 
> 
>     Treat the system like you would any other "normal" protein.  Run
>     pdb2gmx on a coordinate file of a single molecule and proceed with
>     building your system, which can include replication (i.e. genconf to
>     get multiple molecules), genbox (to add other molecules and
>     solvent), and genion.  For systems with different numbers of
>     arginine, simply alter the corresponding line in the [molecules]
>     directive of the topology that pdb2gmx wrote.
> 
>     -Justin
> 
>         On Thu, Aug 11, 2011 at 3:15 PM, Mark Abraham
>         <Mark.Abraham at anu.edu.au <mailto:Mark.Abraham at anu.edu.au>
>         <mailto:Mark.Abraham at anu.edu.__au
>         <mailto:Mark.Abraham at anu.edu.au>>> wrote:
> 
>            On 11/08/2011 7:24 PM, shahid nayeem wrote:
> 
>                Hi Justin
>                I prepared a box of SOL and arginine Hydrochloride. But
>             when I
>                solvate my protein with this box now the positively charged
>                arginine is as solvent and this causes problem in grompp.
>             It gives
>                error like "No such Molecule types ARG" etc. Solvating
>             arginine
>                with water and preparing a box was without error. which
>             forcefield
>                in gromacs has inbuilt .itp file for free amino acid
>             which I can
>                include in my .top file.
> 
> 
>            See
>         http://www.gromacs.org/__Documentation/How-tos/__Multiple_Chains
>         <http://www.gromacs.org/Documentation/How-tos/Multiple_Chains>.
>            Pre-position the non-water molecules, use pdb2gmx, solvate.
> 
>            Mark
> 
> 
>                Shahid Nayeem
> 
>                On Fri, Jul 29, 2011 at 5:02 PM, Justin A. Lemkul
>             <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>                <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>> wrote:
> 
> 
> 
>                    shahid nayeem wrote:
> 
>                        Dear All I am trying to find the topology and
>             parameterof
>                        free Arginine Hydrchloride molecule in gromacs
>             force-field
>                        format. Developing it in Pro-Drg will not serve
>             as  I will
>                        need some other parametrization tool to check it
>             charges.
>                        If someone can help, I will be grateful.
> 
> 
>                    Isn't this just a protonated arginine (normal state for
>                    neutral pH) with a chloride counterion?  There's nothing
>                    special about it, just run a coordinate file through
>             pdb2gmx
>                    with the force field of your choice.
> 
>                    -Justin
> 
>                    --         ==============================__==========
> 
>                    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
>             <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
>     <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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