[gmx-users] top/itp file to show parameters explicitly

Alan alanwilter at gmail.com
Wed May 23 10:42:45 CEST 2012


Thanks Justin, you were right. In the end gmxdump helped to clear some
doubts but I wished it would be less painfully.

Cheers,

Alan

On 22 May 2012 12:36, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> On 5/22/12 12:46 PM, Alan wrote:
>
>> Hi Justin, your suggestion got close. However, let me give an example.
>> You can
>> use the Gly-Gly-Gly example I am attaching and do this:
>>
>> pdb2gmx -ff amber99sb -f aGGG.pdb -o aGGG_.pdb -p aGGG.top  -water none
>> /sw/bin/grompp -c aGGG_.pdb -p aGGG.top -f SPE.mdp -o aGGG.tpr -pp
>> aGGGp.top
>>
>> if you look at aGGGp.top I can't find which parameters were used for
>>
>> [ dihedrals ]
>> ;  ai    aj    ak    al funct            c0            c1            c2
>>    c3            c4            c5
>>     2     1     5     6     9
>>
>> I.e., for proper dihedral (H1-     N-    CA-   HA1), I can't find
>> in amber99sb.ff/forcefield.itp any combination that handles parameters for
>> X-N-CA-X or X-CA-N-X, so how grompp is interpreting this dihedral?
>>
>>
> Make sure you're looking at types, not names.  The type sequence here is
> H-N3-CT-HP, which I think is mapped to this dihedral:
>
>  X   CT  N3  X     9       0.0      0.65084     3  ; JCC,7,(1986),230
>
> Running gmxdump on the .tpr file will show it for sure; I had assumed it
> would be in the post-processed topology as well, but I guess not.
>
> -Justin
>
>  Thanks,
>>
>> Alan
>>
>> On 21 May 2012 18:50, Justin A. Lemkul <jalemkul at vt.edu
>> <mailto:jalemkul at vt.edu>> wrote:
>>
>>
>>
>>    On 5/21/12 2:43 PM, Alan wrote:
>>
>>        Hi there,
>>
>>        Is there an option in pdb2gmx that when generating the top/itp
>> file, it
>>        could
>>        show the parameters explicitly? e.g.:
>>
>>        Instead of:
>>        [ dihedrals ]
>>        ;  ai    aj    ak    al funct            c0            c1
>>    c2
>>            c3
>>             5    13    11    12     4
>>            11    15    13    14     4
>>            15    23    21    22     4
>>            21    25    23    24     4
>>            25    32    31    33     4
>>
>>        (my hard hand modifications)
>>
>>        [ dihedrals ] ; impropers
>>        ; treated as propers in GROMACS to use correct AMBER analytical
>> function
>>        ;    i      j      k      l   func   phase     kd      pn
>>              5     13     11     12      4   180.00  43.93200   2 ;
>> CA-     N-
>>        C-     O
>>             11     15     13     14      4   180.00   4.60240   2 ;
>>  C-    CA-
>>        N-     H
>>             15     23     21     22      4   180.00  43.93200   2 ;
>> CA-     N-
>>        C-     O
>>             21     25     23     24      4   180.00   4.60240   2 ;
>>  C-    CA-
>>        N-     H
>>             25     32     31     33      4   180.00  43.93200   2 ;
>> CA-   OC1-
>>        C-   OC2
>>
>>        I mean, if the parameters that are hiding in e.g.
>>        ...gromacs/top/amber99sb.ff
>>        could be showed in the top/itp file for human readers, that would
>> be great.
>>
>>
>>    You can obtain these parameters (I believe) by running grompp with the
>> -pp
>>    option.  If you think it would be a useful feature for pdb2gmx, file a
>>    feature request on redmine.gromacs.org <http://redmine.gromacs.org>.
>>
>>    -Justin
>>
>>    --
>>    ==============================**__==========
>>
>>
>>    Justin A. Lemkul, Ph.D.
>>    Research Scientist
>>    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://vt.edu/Pages/Personal/justin>
>>    <http://www.bevanlab.biochem.**vt.edu/Pages/Personal/justin<http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin>
>> >
>>
>>    ==============================**__==========
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>> --
>> Alan Wilter SOUSA da SILVA, DSc
>> Bioinformatician, UniProt - PANDA, EMBL-EBI
>> CB10 1SD, Hinxton, Cambridge, UK
>> +44 1223 49 4588
>>
>>
> --
> ==============================**==========
>
> Justin A. Lemkul, Ph.D.
> Research Scientist
> Department of Biochemistry
> Virginia Tech
> Blacksburg, VA
> jalemkul[at]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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-- 
Alan Wilter SOUSA da SILVA, DSc
Bioinformatician, UniProt - PANDA, EMBL-EBI
CB10 1SD, Hinxton, Cambridge, UK
+44 1223 49 4588
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