[gmx-users] Simulated annealing

Justin A. Lemkul jalemkul at vt.edu
Mon Mar 23 21:27:49 CET 2009



jayant james wrote:
> Hi!
> I have two phosphorylated serines which form part of peptide that I want 
> to perform simulated annealing. But the catch is the SEP group is read 
> as a Non-Protein and so it is present in two T-coupling groups, the 
> Non-Potein and the protein group I want to heat. I need to remove this 
> group (SEP-phosphorylated serine) from the Non-Protein group. The 
> Non-Protein group contains about 20,000 atoms (water, counterions and 
> also the SEP group). So how can I remove this group from the Non-Protein 
> group?

Add it to aminoacids.dat, and increment the number at the top of the file.

-Justin

> Welcoming your suggestions
> Jayant James
> 
> 
>  
> On Sat, Mar 21, 2009 at 4:52 AM, Justin A. Lemkul <jalemkul at vt.edu 
> <mailto:jalemkul at vt.edu>> wrote:
> 
> 
> 
>     jayant james wrote:
> 
>         Hi !
>         I am attempting to do a simulated annealing and running into
>         problem.
>         Let me give a introduction to my system. I have a segment of a
>         protein that was not crystallographyically resolved, but was
>         later resolved by NMR.
>         So I ligated the NMR structure to the crystal structure  and in
>         an attempt to find the correct orientation of the NMR segment in
>         the crystal structure I planned to do a simulated annealing run
>         specifically to this ligated NMR segment. Having ligated this
>         NMR segment to the crystal structure I gave the pdb2gmx command,
>         then created a box, filled it with water and performed a
>         distance restrained energy minimization (wherein I input some
>         FRET distances as distance restraints). Its all fine till this
>         step. Now I create an index group that has the NMR group as the
>         third group in the temperature coupling, the other two are
>         Protein and Non-Protein. when I run the grompp to start a
>         simulated annealing run I get a message stating that the NMR
>         group's atoms are also found in the Protein group. Gromacs is
>         right in detecting this problem. As I cannot have the same amino
>         acids in 2 different groups which are coupled to two different
>         temperatures. So how am I to attempt this simulated annealing
>         because the program does not want to have the NMR group present
>         in the Protein group?
> 
> 
>     You will need to make special index groups, i.e.:
> 
>     r 1-x (for the appended segment)
>     r x-y (the rest of the protein)
> 
>     These groups can be used as your tc-grps.
> 
>     -Justin
> 
>         So say I delete the NMR segment that was appended to the crystal
>         structure how and which stage do I integrate the NMR group that
>         I wanted to perform the simulated annealing on, into the system?
>          Thanks
>         Jayant
>          *The pr.mdp file is as below*
>          
>         ; Berendsen temperature coupling is on in two groups
> 
>         Tcoupl              = Berendsen
> 
>         tc-grps               =  Protein   Non-Protein   NMR-group    
>         tau_t               =  0.1           0.1           0.1
> 
>         ref_t               =  300           300           300
> 
>         ; Energy monitoring
> 
>         energygrps      =  Protein       Non-Protein    NMR-group
>         ; Pressure coupling is not on
> 
>         Pcoupl              =  parrinello-rahman
> 
>         tau_p               =  0.5
> 
>         compressibility     =  4.5e-5
> 
>         ref_p               =  1.0
> 
>         ; Generate velocites is on at 300 K.
> 
>         gen_vel             =  yes
> 
>         gen_temp            =  300.0
> 
>         gen_seed            =  173529
> 
>         ;
> 
>         ;
> 
>         ;
> 
>         ;simulated annealing
> 
>         ;Type of annealing form each temperature group (no/single/periodic)
> 
>         annealing       = no    no  single
> 
>         ;
> 
>         ;Number of annealing points to use for specifying annealing in
>         each group
> 
>         annealing_npoints      0  0  9
> 
>         ;
> 
>         ; List of times at the annealing points for each group
> 
>         annealing_time       =  0 25 50 75 100 125 150 175 200
> 
>         ; Temp.at each annealing point, for each group.
> 
>         annealing_temp      =  300 350 400 450 500 450 400 350 300
>          *The error messge is given below*
>          
>          
>         creating statusfile for 1 node...
> 
>          
>         Back Off! I just backed up mdout.mdp to ./#mdout.mdp.14#
> 
>         checking input for internal consistency...
> 
>         calling /usr/bin/cpp...
> 
>         processing topology...
> 
>         Generated 279 of the 1225 non-bonded parameter combinations
> 
>         Excluding 3 bonded neighbours for Protein_D 1
> 
>         Excluding 2 bonded neighbours for SOL 72948
> 
>         Excluding 1 bonded neighbours for NA+ 214
> 
>         Excluding 1 bonded neighbours for CL- 207
> 
>         processing coordinates...
> 
>         double-checking input for internal consistency...
> 
>         Velocities were taken from a Maxwell distribution at 300 K
> 
>         renumbering atomtypes...
> 
>         converting bonded parameters...
> 
>         #   G96BONDS:   4588
> 
>         #  G96ANGLES:   6638
> 
>         #      PDIHS:   2521
> 
>         #      IDIHS:   2044
> 
>         #       LJ14:   7634
> 
>         #     DISRES:   22
> 
>         #     SETTLE:   72948
> 
>         initialising group options...
> 
>         processing index file...
> 
>         WARNING 1 [file "new.top", line 28039]:
> 
>          T-Coupling group Protein has fewer than 10% of the atoms (4550
>         out of
> 
>          223817)
> 
>          Maybe you want to try Protein and Non-Protein instead?
> 
>         WARNING 2 [file "new.top", line 28039]:
> 
>          T-Coupling group Non-Protein has fewer than 10% of the atoms (2
>         out of
> 
>          223817)
> 
>          Maybe you want to try Protein and Non-Protein instead?
> 
>          
>         -------------------------------------------------------
> 
>         Program grompp, VERSION 3.3.3
> 
>         Source code file: readir.c, line: 843
> 
>          
>         Fatal error:
> 
>         Atom 2589 in multiple T-Coupling groups (1 and 3)
> 
>         -------------------------------------------------------
> 
>         ** ** *The commands that I use are given below*
>         ** #pdb2gmx -f start.pdb -p new  -o new -ignh -merge
> 
>          
>          
>         #creating a box and addition of water molecules
> 
>          
>         #editconf -f new.gro -o out -c  -princ -d 2.2
> 
>         #genbox -cp out -cs -o check
> 
>         #editconf -f check  -o check.pdb
> 
>         #rasmol check.pdb
> 
>          
>          
>         #Energy minimization and addition of ions to neutralise the system
> 
>          
>         #grompp -f em.mdp -c check -p new.top -o em.tpr
> 
>         #genion -s em.tpr -o next  -p new -random -g -neutral -conc 0.15
>         #pname -Na -np 13
> 
>         #editconf -f next.gro -o next.pdb
> 
>         #rasmol next.pdb
> 
>          
>         #option 13 for SOL
> 
>          
>         #Running the EM. Here change the Na to NA+ in topology  file and
>         I/P *.gro file.
> 
>          
>         #grompp -f em.mdp -c next.gro -p new.top -o em.tpr
> 
>         #mdrun -v -s em -x em -o em -c em.gro &
> 
>         #editconf -f em.gro -o em.pdb
> 
>         #rasmol em.pdb
> 
>          
>         *This is where the problem begins*
> 
>         #Running MD.
> 
>         grompp -f pr.mdp -c em.gro -o pr.tpr -p new.top -n index
> 
>         #mdrun -s pr -e pr -g md -o traj.trr -c pr.gro &
> 
>          
>         #extending
> 
>         #tpbconv -s ../pr.tpr -f 300.xtc  -e ../ener.edr -o 1ns.tpr
>         -until 1000
> 
>         #mdrun -s 1ns.tpr -o 1ns.trr &
> 
> 
> 
>         -- 
>         Jayasundar Jayant James
> 
>         www.chick.com/reading/tracts/0096/0096_01.asp
>         <http://www.chick.com/reading/tracts/0096/0096_01.asp>
>         <http://www.chick.com/reading/tracts/0096/0096_01.asp>)
> 
> 
>         ------------------------------------------------------------------------
> 
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> 
> 
>     -- 
>     ========================================
> 
>     Justin A. Lemkul
>     Graduate Research Assistant
>     ICTAS Doctoral Scholar
>     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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> 
> 
> 
> -- 
> Jayasundar Jayant James
> 
> www.chick.com/reading/tracts/0096/0096_01.asp 
> <http://www.chick.com/reading/tracts/0096/0096_01.asp>)
> 

-- 
========================================

Justin A. Lemkul
Graduate Research Assistant
ICTAS Doctoral Scholar
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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