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

Mark Abraham Mark.Abraham at anu.edu.au
Thu Jan 27 13:16:58 CET 2011


On 27/01/2011 11:11 PM, bharat gupta wrote:
> 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 ..

That suggests the problem was in the structure you started the 
simulation from, like I've suggested a few times now :-)

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

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