[gmx-users] change in secondary structure after npt equilibration

bharat gupta bharat.85.monu at gmail.com
Fri Jan 28 14:34:58 CET 2011


I searched the user list .. I am not able to find how to apprach this
problem .. I want to check whether water is entering the protein and
interacting with chromophore or not ?? ...

On Fri, Jan 28, 2011 at 5:10 AM, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> bharat gupta wrote:
>
>> Thanks for the advice ... I have checked all the equilibration graphs and
>> they have converged well... I want to know one more thing about the anaylsis
>> of simulation result.... I want to know whether the water molecules are
>> entering in the protein molecule or not and if so how to track down those
>> specific water molecules .. ( since I am simulating a GFP which is well
>> protected from water and I have made some changes in the structure of GFP
>> and then simulating it to see how this leads to change in protein structure
>> ?? )
>>
>>
> Watching the trajectory is the first step.  There may be ways to quantify
> these water molecules, using e.g. g_select or perhaps trjorder, but I can't
> say that I actually know how to do that.  I've never had to try :)
>
> -Justin
>
>  On Fri, Jan 28, 2011 at 5:00 AM, Justin A. Lemkul <jalemkul at vt.edu<mailto:
>> jalemkul at vt.edu>> wrote:
>>
>>
>>
>>    sonali dhindwal wrote:
>>
>>        Hi Justin,
>>
>>        I am writing in this correspondence, because I also had the same
>>        query once that secondary structure changes after equilibration,
>>        and you are right that visualisation programs are not always
>>        reliable.
>>        You also mentioned this time that we should check wether
>>        equilibration sufficiently converged all of the thermodynamic
>>        observables. It will be very kind of you if you can throw some
>>        light in this regard that how these observables should be checked.
>>
>>
>>    Presumably, you've chosen an ensemble (NVT, NPT, etc) that
>>    represents some set of desirable conditions.  You have to make sure
>>    that properties like temperature, pressure, density, energy, etc
>>    have converged, otherwise the system is not yet equilibrated under
>>    those conditions.
>>
>>    -Justin
>>
>>        Thanks and Regards
>>
>>        --         Sonali Dhindwal
>>
>>        “Live as if you were to die tomorrow. Learn as if you were to
>>        live forever.”
>>
>>
>>        --- On *Fri, 28/1/11, Justin A. Lemkul /<jalemkul at vt.edu
>>        <mailto:jalemkul at vt.edu>>/* wrote:
>>
>>
>>           From: Justin A. Lemkul <jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>>
>>
>>           Subject: Re: [gmx-users] change in secondary structure after npt
>>           equilibration
>>           To: "Discussion list for GROMACS users"
>>        <gmx-users at gromacs.org <mailto:gmx-users at gromacs.org>>
>>
>>           Date: Friday, 28 January, 2011, 5:53 PM
>>
>>
>>
>>
>>           bharat gupta wrote:
>>            > Hi,
>>            >
>>            >
>>            > I am doing a simulation of a 230 amino acid protein for
>>        3ns ...
>>           and I have completed the npt equilibration step .. After
>>        retrieving
>>           the structure from npt step and viewing it in pymol, reveals
>> that
>>           some portion of the beta strand got changed to a loop but when I
>>           visualized the same structure in VMD I found that nothing has
>>           happened to the structure .. In order to confirm more ... I
>>           generated the SS profile using dssp and I found that , the dssp
>>           shows E i.e. sheet for that region .. So what shall i do next
>> ...
>>           shall I continue with the production step or not ??
>>            >
>>
>>           Visualization programs are not always reliable in what they show
>>           you, we've discussed that.  Methods like DSSP and STRIDE are far
>>           more trustworthy, and seem to indicate that your structure is
>>        fine.     What you should be much more concerned with at this
>>        point is whether
>>           or not your equilibration sufficiently converged all of the
>>           thermodynamic observables.
>>
>>           -Justin
>>
>>            > -- 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>
>>        </mc/compose?to=monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>>
>>           <mailto:monu46010 at yahoo.com <mailto:monu46010 at yahoo.com>
>>        </mc/compose?to=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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>>
>>    --     ========================================
>>
>>    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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