Jacob Harvey wrote:
Justin,

How do I go about running topolgen on a linux system? There doesn't seem to be instructions for use, but I'm not familiar with perl scripts. Also I'd just like to say thank you for all your help. You've been really good with responding to my e-mail. I know that you have referenced chapter 5 in the manual multiple times, and I can assure you that I have read that chapter several times. I am a first year graduate student who is very new to molecular dynamics so some of the material is not trivial to me. Thank you again!


To execute:

perl topolgen.pl input.pdb

Guess I forgot to include that in the README; my mistake. I'm working on making the script better, so I'll update that for a future release. Also be warned that I have not extensively tested the script beyond some basic small molecules. Please run some test simulations before collecting any real data.

There are also a number of tutorials on the Gromacs wiki. The one written by Tsjerk is especially good at diagramming the flow of the programs, input/output, and how everything is put together. If you are unfamiliar with Gromacs, try out some tried-and-true methodology on known systems before simulating some bizarre system. It will save you a lot of headaches.

-Justin

Jacob Harvey

On Sat, Apr 4, 2009 at 3:17 PM, Justin A. Lemkul <[email protected] <mailto:[email protected]>> wrote:



    Jacob Harvey wrote:

        Thank you for your help Justin. I have corrected my naming
        problem in the pdb file. However, I am still getting errors. It
        does not seem to recognize the residues. BUT I dont actually
        have "residues" in my system, because I am not modeling a
        protein. So I am not sure what to put in the residue name
        column. Gromacs does work on molecules that are not proteins
        correct? My molecules are histidine like so I tried putting HIS
        as the residue name, but I got the error:


    If you want to use pdb2gmx to automatically generate your topology,
    you have to ensure that the appropriate .rtp entry is present within
    the desired force field and has the same name as the building block
    you are trying to use (again, this is spelled out in Chapter 5 of
    the manual).  If you call your molecule "HIS," then pdb2gmx will not
    magically build a random molecule; it will try to build histidine,
    based on the [ HIS ] entry in the .rtp file, so it will look for the
    exact atomic entries for histidine, no more no less.

    If you want a topology for an arbitrary molecule, you *can not* use
    pdb2gmx (unless you build the .rtp entry yourself).  You will have
    to build it by hand, or use another program to build the .top file.
     I just uploaded a script I wrote to build an OPLS-AA topology from
    a .pdb file to the Users Contributions section on the website, but
    it does not assign atom types or charges (yet); it is up to you to
    assign the parameters and verify them.


        "Fatal error:
        Residue 'H' not found in residue topology database"


    Because it is not histidine.


        When I dont put anything in that column I get the error:

        "Fatal error:
        Residue '' not found in residue topology database"


    Because of a formatting error (the fact that your residue is either
    blank, or the number 2).


        And when I just generically call everything solvent and put SOL
        in that column I get:

        "Fatal error:
        Residue 'S' not found in residue topology database"


    Probably another formatting issue.  But none of the above actually
    solve your problem, you're just trying to fool pdb2gmx into being
    magic, which it is not.

    -Justin

        You get the picture here. Does anyone have any solutions to my
        residue naming problem? Thank you.

        here is my pdb file:

        HETATM    1  CT          2      -4.438   3.334   2.988
        HETATM    2  CT          2       0.588   3.313   0.517
        HETATM    3  CT          2       5.476   3.310  -2.216
        HETATM    4  HC          2      -4.134   2.590   3.731
        HETATM    5  HC          2      -5.525   3.438   3.047
        HETATM    6  HC          2      -3.996   4.291   3.276
        HETATM    7  HC          2       1.480   3.111   1.117
        HETATM    8  HC          2      -0.266   3.349   1.200
        HETATM    9  HC          2       0.702   4.307   0.076
        HETATM   10  HC          2       6.375   3.525  -1.633
        HETATM   11  HC          2       4.648   3.862  -1.761
        HETATM   12  HC          2       5.628   3.709  -3.223
        HETATM   13  CT          2      -3.996   2.922   1.581
        HETATM   14  HC          2      -2.902   2.862   1.545
        HETATM   15  HC          2      -4.281   3.703   0.865
        HETATM   16  CT          2       0.394   2.242  -0.557
        HETATM   17  HC          2      -0.485   2.486  -1.167
        HETATM   18  HC          2       1.250   2.252  -1.242
        HETATM   19  CT          2       5.188   1.805  -2.247
        HETATM   20  HC          2       6.018   1.286  -2.742
        HETATM   21  HC          2       4.300   1.615  -2.864
        HETATM   22  CT          2      -4.587   1.582   1.127
        HETATM   23  HC          2      -5.682   1.638   1.161
        HETATM   24  HC          2      -4.298   0.792   1.828
        HETATM   25  CT          2       0.235   0.836   0.028
        HETATM   26  HC          2      -0.616   0.818   0.720
        HETATM   27  HC          2       1.117   0.581   0.625
        HETATM   28  CT          2       4.981   1.206  -0.852
        HETATM   29  HC          2       4.152   1.720  -0.350

        Jacob Harvey

        On Sat, Apr 4, 2009 at 2:29 PM, Justin A. Lemkul
        <[email protected] <mailto:[email protected]>
        <mailto:[email protected] <mailto:[email protected]>>> wrote:



           Jacob Harvey wrote:

               Dear All,

               I am trying to use the OPLS-AA force field to model some
               imidazole containing compounds. I've noticed that imidazole
               units are referenced in the ffoplsaa.atp file as the
        following:

               opls_557   14.00670  ; N1  in imidazole
                opls_558   12.01100  ; C2  in imidazole
                opls_559   14.00670  ; N3  in imidazole
                opls_560   12.01100  ; C4  in imidazole
                opls_561   12.01100  ; C5  in imidazole
                opls_562    1.00800  ; H1  in imidazole
                opls_563    1.00800  ; H2  in imidazole
                opls_564    1.00800  ; H4  in imidazole
                opls_565    1.00800  ; H5  in imidazole

               But there are no parameters for these atoms in the
        ffoplsaa.rtp
               file. Does anyone know how I can go about naming these
        atoms in
               my pdb file? Thank you in advance.


           Not every compound is present in a .rtp file.  Check out its
           contents and you'll see what it has - pretty much just amino
        acids.
            The charges on each atom are not specific to an atom type,
        they are
           specific to a chemical species for which the parameterization
        scheme
           has been conducted.  Lennard-Jones parameters are specified in
           ffoplsaanb.itp.

           I suggest a thorough read of Chapter 5 of the manual to
        understand
           the contents of these database-type files, and how they are
        used in
           assembling a topology.

           -Justin

               Jacob Harvey

               --        --
               Jacob Harvey

               Graduate Student

               University of Massachusetts Amherst

               [email protected] <mailto:[email protected]>
        <mailto:[email protected] <mailto:[email protected]>>
               <mailto:[email protected] <mailto:[email protected]>
        <mailto:[email protected] <mailto:[email protected]>>>



------------------------------------------------------------------------

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           --    ========================================

           Justin A. Lemkul
           Graduate Research Assistant
           ICTAS Doctoral Scholar
           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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-- --
        Jacob Harvey

        Graduate Student

        University of Massachusetts Amherst

        [email protected] <mailto:[email protected]>
        <mailto:[email protected] <mailto:[email protected]>>


        ------------------------------------------------------------------------

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-- ========================================

    Justin A. Lemkul
    Graduate Research Assistant
    ICTAS Doctoral Scholar
    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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    <mailto:[email protected]>
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--
--
Jacob Harvey

Graduate Student

University of Massachusetts Amherst

[email protected] <mailto:[email protected]>

--
========================================

Justin A. Lemkul
Graduate Research Assistant
ICTAS Doctoral Scholar
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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