[gmx-users] Re: change in the secondary structure after simulation

bharat gupta bharat.85.monu at gmail.com
Thu Jan 27 13:11:40 CET 2011


I used the same .mdp files that are given in the lysozyme tutorial .. Since
I was knowing what all parameters to change .. but after energy minimization
and equilibration steps , the graphs that I got were fine ... even the rmsd
graph of the final structure is also fine .. I have attached the final rmsd
graph of the structure ..




On Thu, Jan 27, 2011 at 3:44 AM, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> bharat gupta wrote:
>
>> I generated the secondary structure profile of structure retrieved from
>> the last frame of the simulation ... In that profile those amino acids that
>> are shown as loops in VMD doesnot have any secondary structure assignment
>> ... it means that during simulation the structure got changed some how ...
>> and It's really surprising ?? ... Can u tell me where can the fault be as I
>> am planning to do the simulation again and this time I will check the
>> structure after every step .. but for that I want to know how can I save the
>> structure after every step say for eg. after energy minimization ..
>>
>>
> Secondary structure is dependent upon the chosen force field and the .mdp
> settings.  Since you've posted neither, there's no way to tell what might be
> to blame.
>
> You can save more frequently by setting the proper output controls.  Read
> in the manual about the nst* options and set the accordingly.
>
> -Justin
>
>  On Thu, Jan 27, 2011 at 8:35 PM, Justin A. Lemkul <jalemkul at vt.edu<mailto:
>> jalemkul at vt.edu>> wrote:
>>
>>
>>
>>    Mark Abraham wrote:
>>
>>
>>
>>        On 01/27/11, *bharat gupta * <bharat.85.monu at gmail.com
>>         <mailto:bharat.85.monu at gmail.com>> wrote:
>>
>>            I actually don't understand exactly what u are asking ..
>>            since I am not an expert with gromacs..
>>
>>
>>        Please leave the old context for the discussion in future
>>        emails. Only you are paying so much attention to your work that
>>        you can be sure of remembering things :-)
>>
>>        If your simulation started with these strands unfolded, then
>>        your problem is somewhere else. However, you have to be able to
>>        tell us what was the initial conformation, and when your "first
>>        trajectory frame" (per last email) happened in the simulation.
>>
>>
>>    I would also add that VMD does a fairly poor job sometimes of
>>    guessing secondary structure.  So if no beta strand was present in
>>    the very first frame, that doesn't necessarily mean the secondary
>>    structure wasn't stable, it just means VMD didn't display it properly.
>>
>>    -Justin
>>
>>        Mark
>>
>>
>>            I don't know when is was written .. Here are some lines from
>>            the log files of simulation ...
>>            Statistics over 1500001 steps using 300001 frames
>>
>>              Energies (kJ/mol)
>>                     Angle    Proper Dih. Ryckaert-Bell.          LJ-14
>>                Coulomb-14
>>               7.35090e+03    4.37413e+02    3.60104e+03    5.26705e+03
>>               2.58894e+04
>>                   LJ (SR)  Disper. corr.   Coulomb (SR)   Coul. recip.
>>                 Potential
>>               1.05399e+05   -2.92853e+03   -6.79288e+05   -1.07015e+05
>>              -6.41286e+05
>>               Kinetic En.   Total Energy    Temperature Pres. DC (bar)
>>            Pressure (bar)
>>               1.03484e+05   -5.37802e+05    3.00003e+02   -2.37485e+02
>>               1.02890e+00
>>              Constr. rmsd
>>               0.00000e+00
>>
>>                     Box-X          Box-Y          Box-Z
>>               7.42618e+00    7.42618e+00    7.42618e+00
>>
>>              Total Virial (kJ/mol)
>>               3.44183e+04    3.40020e+01   -1.17357e+01
>>               3.42160e+01    3.45369e+04   -2.46337e+01
>>              -1.16644e+01   -2.48479e+01    3.44949e+04
>>
>>              Pressure (bar)
>>               1.99809e+00    9.48448e-02    4.57909e-01
>>               7.74354e-02    4.97824e-01    1.84797e+00
>>               4.52125e-01    1.86535e+00    5.90776e-01
>>
>>              Total Dipole (D)
>>              -1.86272e+02    4.46310e+01    2.08554e+02
>>
>>                 T-Protein  T-non-Protein
>>               2.99904e+02    3.00013e+02
>>
>>
>>            M E G A - F L O P S   A C C O U N T I N G
>>
>>
>>            There were in total 1502 frames (as shown in VMD )...
>>            I don't know about how it compared with the coordinates of
>>            the structure that I gave to grompp
>>
>>            --------
>>
>>            Pls guide
>>
>>
>>
>>
>>            --             Bharat
>>            Ph.D. Candidate
>>            Room No. : 7202A, 2nd Floor
>>            Biomolecular Engineering Laboratory
>>            Division of Chemical Engineering and Polymer Science
>>            Pusan National University
>>            Busan -609735
>>            South Korea
>>            Lab phone no. - +82-51-510-3680, +82-51-583-8343
>>            Mobile no. - 010-5818-3680
>>            E-mail : monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>
>>            <mailto:monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>>
>>
>>
>>
>>    --     ========================================
>>
>>    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
>>
>>    ========================================
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>>
>>
>>
>> --
>> Bharat
>> Ph.D. Candidate
>> Room No. : 7202A, 2nd Floor
>> Biomolecular Engineering Laboratory
>> Division of Chemical Engineering and Polymer Science
>> Pusan National University
>> Busan -609735
>> South Korea
>> Lab phone no. - +82-51-510-3680, +82-51-583-8343
>> Mobile no. - 010-5818-3680
>> E-mail : monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>
>>
>>
> --
> ========================================
>
> 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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-- 
Bharat
Ph.D. Candidate
Room No. : 7202A, 2nd Floor
Biomolecular Engineering Laboratory
Division of Chemical Engineering and Polymer Science
Pusan National University
Busan -609735
South Korea
Lab phone no. - +82-51-510-3680, +82-51-583-8343
Mobile no. - 010-5818-3680
E-mail : monu46010 at yahoo.com
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