[gmx-users] so difficult problem

Mark Abraham Mark.Abraham at anu.edu.au
Wed Jan 12 12:29:36 CET 2011


On 12/01/2011 9:37 PM, mohsen ramezanpour wrote:
> Dear Dr,Tsjerk
> I want to estimate protein-drug binding free energy.
> I am using umbrella sampling for this mean.
> my drug is inside of a hole in protein. then I have to rotate my 
> system to can fit the pulling line along one box axis.
> besides I have to pull drug not at direction which connect COM of 
> protein and drug,but it is better to pull it along line which connects 
> drug to
> a residue inside of hole.

I would

1) take my starting bound configuration,
2) strip away anything except the protein complex,
3) delete the box information,
4) rotate the complex with editconf until I was happy with its orientation,
5) then generate a suitable box around that orientation,
6) do EM
7) solvate and neutralize
8) do EM
9) etc.

Mark

>
> I rotated box with editconf ,solvated system with genbox,neutralized 
> with genion,
> now I want to generate NPT and then generating configuration as 
> umbrella sampling tutorial.
>
>
>
> On Wed, Jan 12, 2011 at 1:53 PM, Tsjerk Wassenaar <tsjerkw at gmail.com 
> <mailto:tsjerkw at gmail.com>> wrote:
>
>     Hi Mohsen,
>
>     You're doing something terribly wrong. But why you want to do what you
>     attempt eludes me. Maybe it helps if you give an explanation of what
>     you want, in stead of what doesn't work. In addition, give the set of
>     commands that bring you up to this point, and not only the output of
>     mdrun. That way we can probably see where you go astray.
>
>     Cheers,
>
>     Tsjerk
>
>
>     On Wed, Jan 12, 2011 at 10:55 AM, mohsen ramezanpour
>     <ramezanpour.mohsen at gmail.com
>     <mailto:ramezanpour.mohsen at gmail.com>> wrote:
>     >
>     > Dear Dr.Tsjerk
>     >
>     > Before doing md for generating NPT, I did an EM,the result was:
>     > poteintial energy:-2.2611160*10^(6)
>     > Max F=4.8960352*10^(4) on atom 5289
>     > Besides I had done EM before on the same system,I just add
>     solvent by genbox
>     > and Ions by genion.
>     > the above result is for Energy minimization after adding ions by
>     genion.
>     >
>     > I did what you said.but when I was generating NPT equilibration
>     > I recieved this massage:
>     >
>     >
>     > Step 0, time 0 (ps)  LINCS WARNING
>     > relative constraint deviation after LINCS:
>     > rms 8.387059, max 321.381958 (between atoms 5289 and 5290)
>     > bonds that rotated more than 30 degrees:
>     >  atom 1 atom 2  angle  previous, current, constraint length
>     >    5293   5294   74.4    0.1137  12.9330      0.1090
>     >    5291   5293   59.1    0.1422  32.1605      0.1390
>     >    5291   5292  103.5    0.1096   9.8747      0.1090
>     >    5289   5291   89.5    0.1383  39.2022      0.1390
>     >    5289   5290   85.7    0.1410  43.8439      0.1360
>     >    5289   5287   85.4    0.1426  44.0196      0.1390
>     >    5287   5288   90.2    0.1091   1.5178      0.1090
>     >    5285   5287   88.7    0.1391   1.9186      0.1390
>     >    5285   5286   41.8    0.1092   0.1322      0.1090
>     >    5284   5293   87.2    0.1429  21.7425      0.1390
>     >    5284   5285   92.4    0.1393   2.0880      0.1390
>     >    5277   5278   79.1    0.1532   0.5213      0.1530
>     >    5276   5284   63.0    0.1394   1.8946      0.1390
>     >    5276   5277   79.2    0.1534   0.7278      0.1530
>     >    5276   5275   79.9    0.1432   0.6036      0.1430
>     >    5274   5275   82.0    0.1431   0.3189      0.1430
>     >    5276   5272   82.1    0.1393   0.6113      0.1390
>     >    5272   5273   74.2    0.1333   0.2251      0.1330
>     >    5272   5270   77.7    0.1332   0.2428      0.1330
>     >    5270   5271   46.5    0.1091   0.1682      0.1090
>     >    5268   5270   36.9    0.1391   0.1854      0.1390
>     >    5273   5266   41.4    0.1334   0.1933      0.1330
>     > Wrote pdb files with previous and current coordinates
>     > step 0Warning: 1-4 interaction between 5272 and 5293 at distance
>     22.443
>     > which is larger than the 1-4 table size 2.400 nm
>     > These are ignored for the rest of the simulation
>     > This usually means your system is exploding,
>     > if not, you should increase table-extension in your mdp file
>     > or with user tables increase the table size
>     >
>     > Please let me know what can I do.
>     > thanks in advance
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     >
>     > On Thu, Jan 6, 2011 at 11:20 PM, Tsjerk Wassenaar
>     <tsjerkw at gmail.com <mailto:tsjerkw at gmail.com>> wrote:
>     >>
>     >> Hi Mohsen,
>     >>
>     >> I think rotating a molecule with editconf will not rotate the
>     box. Then
>     >> again, if it did, it would result in a box violating Gromacs
>     requirements.
>     >> Either way, it's not going to work like that. Build a new box after
>     >> rotation... And have a good look at what you're actually trying
>     now by
>     >> taking the rotated system and stack it a few times using
>     genconf -nbox 2 2 2
>     >>
>     >> Cheers,
>     >>
>     >> Tsjerk
>     >>
>     >> On Jan 6, 2011 7:22 PM, "mohsen ramezanpour"
>     >> <ramezanpour.mohsen at gmail.com
>     <mailto:ramezanpour.mohsen at gmail.com>> wrote:
>     >>
>     >> Dear Amit
>     >> I entered these commands for rotating box:
>     >> editconf   -f  conf.gro  -o  output.pdb   -rotate  0   0  25.4
>     >> and then:
>     >> editconf   -f output.pdb  -o  newbox.pdb   -rotate   0 
>     127.67548  0
>     >> as a result my molecul is located out of box totally,of course
>     drug and
>     >> protein are bind to eachother yet.
>     >> thanks in advance for your attention and reply
>     >>
>     >> On Tue, Jan 4, 2011 at 1:25 PM, Amit Choubey
>     <kgp.amit at gmail.com <mailto:kgp.amit at gmail.com>> wrote: >
>     >> > Could you post the e...
>     >>
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>
>     --
>     Tsjerk A. Wassenaar, Ph.D.
>
>     post-doctoral researcher
>     Molecular Dynamics Group
>     * Groningen Institute for Biomolecular Research and Biotechnology
>     * Zernike Institute for Advanced Materials
>     University of Groningen
>     The Netherlands
>     --
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