rams rams wrote:
Dear Justin,

I am absolutely sorry for the discomfort. Since this is the first time I am using Gromacs, so things are not clear to me so I am trying things very randomly thats why I could not keep update the things. Here I restarted every thing and have a look at and let me know your suggestions:

pdb2gmx -f insu.pdb -p insu_p.top -o insu_p.pdb –ter –merge

(since I removed all the hydrogens in my starting insu.pdb so didnt used -ignh here)

Well, assuming you have all the correct hydrogens in the right place, that's fine, but in general, it is very easy to let pdb2gmx do the work for you and use -ignh. If it generated the topology for you, then that's fine.

editconf -f insu_p.pdb -o insu_pb.pdb -box 6.0 6.0 6.0 -center 3.0 3.0 3.0

genbox -cp insu_pb.pdb -cs spc216.gro -o insu_pw.pdb -p insu_p.top

grompp -f eminimization.mdp -c  insu_pw.pdb -p insu_p.top -o MM_insu.tp

genion -s MM_insu.tpr -o insu_pwi.pdb -conc 0.008 –neutral

pdb2gmx -f insu_pwi.pdb -p insu_pwi.top -o insu_pwi2MM.pdb -inter –merge -ignh


Here's where your problem is. This step is unnecessary! Once you have the topology, there is no need to re-process with pdb2gmx. Once you have added solvent and ions, simply make the changes to your topology with a text editor.

grompp -f eminimization.mdp -c insu_pwi2MM.gro -p insu_pwi.top -o MM_insu.tpr



It has already been correctly pointed out by another user that you specified -o .pdb in the above step, but then called for the .gro equivalent here. That would be a problem.

Basically, once the genion step is done, and you have made the appropriate changes to the topology (which can also be done with the -p flag of genion), then proceed to grompp.

This makes much more sense, and it is easier to get help when it is clearly presented like this!

-Justin


The following is the error:




Back Off! I just backed up mdout.mdp to ./#mdout.mdp.6#
checking input for internal consistency...
calling /lib/cpp...
processing topology...
Generated 716 of the 2628 non-bonded parameter combinations
Generating 1-4 interactions: fudge = 1
Generated 1046 of the 2628 1-4 parameter combinations
Excluding 3 bonded neighbours for Protein 1
turning all bonds into constraints...
Excluding 2 bonded neighbours for SOL 6878
turning all bonds into constraints...
NOTE:
  System has non-zero total charge: -2.000000e+00

processing coordinates...
-------------------------------------------------------
Program grompp, VERSION 3.3.1
Source code file: futil.c, line: 340

File input/output error:
insu_pwi2MM.gro


Ram.





On Mon, Jun 30, 2008 at 6:45 AM, Justin A. Lemkul <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote:

    It would be helpful if all of this was on one thread, with replies
    embedded.  I have sent several replies to your questions, all of
    which have gone unacknowledged.  It makes it very difficult for
    anyone (myself or someone else) to give advice if we don't know
    what you're doing or what you've tried.  Even if something didn't
    work based on what I, or anyone else, tells you, it is nice to
    know that "I tried this, but I still have a problem, which is
    shown here: (exact error/warning/problem)."

    As I've said before, exact procedural details of what you've done
    are essential for sorting out strange problems like this.  This
    means - *exact* (copy and paste) command lines from pdb2gmx, and
    any error messages you receive.  Also, any manipulations you have
    made to your input .pdb file.  It seems to me that you've probably
    edited your file to have only one chain identifier, and hence why
    pdb2gmx is trying to make everything one molecule.

    The -merge option of pdb2gmx is what you want (see pdb2gmx -h).
     If the following command line doesn't work, it would be nice to
    see an exact reason (i.e., copy/paste from the
    error/warning/whatever):

    pdb2gmx -f (input).pdb -ignh -ter -merge

    I got the above to work perfectly on an insulin structure I found
    in the RCSB (1ZNI), after deleting chains C and D from the .pdb
    file.  If your structure continues to give you headaches, try this
    one to make sure that your Gromacs installation is working
    properly (something I inquired about several days ago...)

    -Justin

    rams rams wrote:

        HI,

        When I use the merge command along with pdb2gmx to form inter
        disulphide bonds between two different chains, its removing a
        water molecule to connect the two ends. Its like forming a
        peptide bond which I dont wish. Is there any way to tell to
        gromacs, to create the inter dishulphide bonds without
        creating the peptide bond between the two chains ?



        On Fri, Jun 27, 2008 at 6:51 PM, rams rams
        <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
        <mailto:[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>> wrote:

           Hi,

           I have three di sulphide bonds in my crystal structure. In the
           topology file it left blanks at the corresponding sulphur
           connectivities (i.e., values corresponding to gb_, ga_. gd_ ).
           When I try to create the .tpr file it complains the following:

           processing topology...
           Generated 716 of the 2628 non-bonded parameter combinations
           Generating 1-4 interactions: fudge = 1
           Generated 1046 of the 2628 1-4 parameter combinations
           WARNING 1 [file "insu_pwi.top", line 607]:
             No default G96Bond types, using zeroes
           WARNING 2 [file "insu_pwi.top", line 745]:
             No default G96Bond types, using zeroes
           WARNING 3 [file "insu_pwi.top", line 2008]:
             No default G96Angle types, using zeroes
           WARNING 4 [file "insu_pwi.top", line 2209]:
             No default G96Angle types, using zeroes
           WARNING 5 [file "insu_pwi.top", line 2345]:
             No default G96Angle types, using zeroes
           WARNING 6 [file "insu_pwi.top", line 2512]:
             No default G96Angle types, using zeroes
           WARNING 7 [file "insu_pwi.top", line 2748]:
             No default Proper Dih. types, using zeroes
           WARNING 8 [file "insu_pwi.top", line 2820]:
             No default Proper Dih. types, using zeroes
           WARNING 9 [file "insu_pwi.top", line 2863]:
             No default Proper Dih. types, using zeroes
           WARNING 10 [file "insu_pwi.top", line 2919]:
             No default Proper Dih. types, using zeroes
           Cleaning up temporary file gromppID2O6e
           -------------------------------------------------------
           Program grompp, VERSION 3.3.1
           Source code file: fatal.c, line: 416

           Fatal error:
           Too many warnings, /usr/local2/gromacs/bin/grompp terminated
           -------------------------------------------------------

           "Encountered Subspace Anomaly" (Star Trek)

           MD_insu.tpr was not created. Check for errors. Exiting ...

           Is there a way to fix it ? Also what are those b_, ga_. gd_
           corresponds to ??

           Ram.


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

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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