[gmx-users] free energy calculations for reference state for constant pH MD simulations...
bipin singh
bipinelmat at gmail.com
Thu Jan 30 04:47:04 CET 2014
You have to define the B state parameters for your deprotonated state
explicitly.
The following line in your topology does not have the parameters for the B
state.
16 opls_270 77 GLU HE2 5 0.45 1.008
You have to set the charges zero in the B state (if you want to consider
the change in electrostatic term only during deprotonation) or else change
it to DUM atom (if you want to change both the vdw and electrostatics terms
during deprotonation).
On Wed, Jan 29, 2014 at 8:15 PM, Ozbil, Mehmet <m.ozbil at umiami.edu> wrote:
>
> Thanks Bipin for the reply.
>
> I went through the Gromacs manual, and thought that I managed to
> incorporate two states (protonated and deprotonated) in my topology file.
> Can anyone who has done it before tell me if I defined both A and B states
> correctly in my .top file.
>
> ;
> ; File 'GLUA_prot_OPLS_p.top' was generated
> ; By user: onbekend (0)
> ; On host: onbekend
> ; At date: Tue Jan 28 13:49:17 2014
> ;
> ; This is a standalone topology file
> ;
> ; It was generated using program:
> ; pdb2gmx - VERSION 4.5.4
> ;
> ; Command line was:
> ; /home/apps/fas/Apps/Gromacs/gromacs-4.5.4-intel/bin//pdb2gmx -f
> GLUA_prot_OPLS.pdb -p GLUA_prot_OPLS_p.top -o GLUA_prot_OPLS_p.gro -inter
> ;
> ; Force field was read from the standard Gromacs share directory.
> ;
>
> ; Include forcefield parameters
> #include "oplsaa.ff/forcefield.itp"
>
> [ moleculetype ]
> ; Name nrexcl
> Protein_chain_A 3
>
> [ atoms ]
> ; nr type resnr residue atom cgnr charge mass typeB
> chargeB massB
> ; residue 77 GLU rtp GLUH q 0.0
> 1 opls_287 77 GLU N 1 -0.3 14.0067
> opls_287 -0.3 14.0067
> 2 opls_290 77 GLU H1 1 0.33 1.008
> opls_290 0.33 1.008
> 3 opls_290 77 GLU H2 1 0.33 1.008
> opls_290 0.33 1.008
> 4 opls_290 77 GLU H3 1 0.33 1.008
> opls_290 0.33 1.008
> 5 opls_299 77 GLU CA 1 0.15 12.011
> opls_299 0.15 12.011
> 6 opls_140 77 GLU HA 1 0.06 1.008
> opls_140 0.06 1.008
> 7 opls_136 77 GLU CB 2 -0.12 12.011
> opls_136 -0.12 12.011
> 8 opls_140 77 GLU HB1 2 0.06 1.008
> opls_140 0.06 1.008
> 9 opls_140 77 GLU HB2 2 0.06 1.008
> opls_140 0.06 1.008
> 10 opls_136 77 GLU CG 3 -0.12 12.011
> opls_136 -0.12 12.011
> 11 opls_140 77 GLU HG1 3 0.06 1.008
> opls_140 0.06 1.008
> 12 opls_140 77 GLU HG2 3 0.06 1.008
> opls_140 0.06 1.008
> 13 opls_267 77 GLU CD 4 0.52 12.011
> opls_267 0.52 12.011
> 14 opls_269 77 GLU OE1 4 -0.44 15.9994
> opls_269 -0.44 15.9994
> 15 opls_268 77 GLU OE2 5 -0.53 15.9994
> opls_268 -0.53 15.9994
> 16 opls_270 77 GLU HE2 5 0.45 1.008
> 17 opls_271 77 GLU C 6 0.7 12.011
> opls_271 0.7 12.011
> 18 opls_272 77 GLU O1 6 -0.8 15.9994
> opls_272 -0.8 15.9994
> 19 opls_272 77 GLU O2 6 -0.8 15.9994
> opls_272 -0.8 15.9994
>
> [ bonds ]
> ; ai aj funct c0 c1 c2 c3
> 1 2 1
> 1 3 1
> 1 4 1
> 1 5 1
> 5 6 1
> 5 7 1
> 5 17 1
> 7 8 1
> 7 9 1
> 7 10 1
> 10 11 1
> 10 12 1
> 10 13 1
> 13 14 1
> 13 15 1
> 15 16 1
> 17 18 1
> 17 19 1
>
> [ pairs ]
> ; ai aj funct c0 c1 c2 c3
> 1 8 1
> 1 9 1
> 1 10 1
> 1 18 1
> 1 19 1
> 2 6 1
> 2 7 1
> 2 17 1
> 3 6 1
> 3 7 1
> 3 17 1
> 4 6 1
> 4 7 1
> 4 17 1
> 5 11 1
> 5 12 1
> 5 13 1
> 6 8 1
> 6 9 1
> 6 10 1
> 6 18 1
> 6 19 1
> 7 14 1
> 7 15 1
> 7 18 1
> 7 19 1
> 8 11 1
> 8 12 1
> 8 13 1
> 8 17 1
> 9 11 1
> 9 12 1
> 9 13 1
> 9 17 1
> 10 16 1
> 10 17 1
> 11 14 1
> 11 15 1
> 12 14 1
> 12 15 1
> 14 16 1
>
> [ angles ]
> ; ai aj ak funct c0 c1 c2
> c3
> 2 1 3 1
> 2 1 4 1
> 2 1 5 1
> 3 1 4 1
> 3 1 5 1
> 4 1 5 1
> 1 5 6 1
> 1 5 7 1
> 1 5 17 1
> 6 5 7 1
> 6 5 17 1
> 7 5 17 1
> 5 7 8 1
> 5 7 9 1
> 5 7 10 1
> 8 7 9 1
> 8 7 10 1
> 9 7 10 1
> 7 10 11 1
> 7 10 12 1
> 7 10 13 1
> 11 10 12 1
> 11 10 13 1
> 12 10 13 1
> 10 13 14 1
> 10 13 15 1
> 14 13 15 1
> 13 15 16 1
> 5 17 18 1
> 5 17 19 1
> 18 17 19 1
>
> [ dihedrals ]
> ; ai aj ak al funct c0 c1 c2
> c3 c4 c5
> 2 1 5 6 3
> 2 1 5 7 3
> 2 1 5 17 3
> 3 1 5 6 3
> 3 1 5 7 3
> 3 1 5 17 3
> 4 1 5 6 3
> 4 1 5 7 3
> 4 1 5 17 3
> 1 5 7 10 3 dih_GLU_chi1_N_C_C_C
> 17 5 7 10 3 dih_GLU_chi1_C_C_C_CO
> 1 5 7 8 3
> 1 5 7 9 3
> 6 5 7 8 3
> 6 5 7 9 3
> 6 5 7 10 3
> 17 5 7 8 3
> 17 5 7 9 3
> 1 5 17 18 3
> 1 5 17 19 3
> 6 5 17 18 3
> 6 5 17 19 3
> 7 5 17 18 3
> 7 5 17 19 3
> 5 7 10 11 3
> 5 7 10 12 3
> 5 7 10 13 3
> 8 7 10 11 3
> 8 7 10 12 3
> 8 7 10 13 3
> 9 7 10 11 3
> 9 7 10 12 3
> 9 7 10 13 3
> 7 10 13 14 3
> 7 10 13 15 3
> 11 10 13 14 3
> 11 10 13 15 3
> 12 10 13 14 3
> 12 10 13 15 3
> 10 13 15 16 3 dih_sidechain_COOH_C_C_O_H
> 14 13 15 16 3 dih_sidechain_COOH_O_C_O_H
>
> [ dihedrals ]
> ; ai aj ak al funct c0 c1 c2
> c3
> 5 18 17 19 1 improper_O_C_X_Y
> 10 14 13 15 1 improper_O_C_X_Y
>
> ; Include Position restraint file
> #ifdef POSRES
> #include "posre.itp"
> #endif
>
> ; Include water topology
> #include "oplsaa.ff/tip3p.itp"
>
> #ifdef POSRES_WATER
> ; Position restraint for each water oxygen
> [ position_restraints ]
> ; i funct fcx fcy fcz
> 1 1 1000 1000 1000
> #endif
>
> ; Include topology for ions
> #include "oplsaa.ff/ions.itp"
>
> [ system ]
> ; Name
> Protein in water
>
> [ molecules ]
> ; Compound #mols
> Protein_chain_A 1
> SOL 4135
>
>
> Thanks,
> Mehmet
>
>
>
> ________________________________________
> From: gromacs.org_gmx-users-bounces at maillist.sys.kth.se <
> gromacs.org_gmx-users-bounces at maillist.sys.kth.se> on behalf of bipin
> singh <bipinelmat at gmail.com>
> Sent: Tuesday, January 28, 2014 2:46 AM
> To: Discussion list for GROMACS users
> Subject: Re: [gmx-users] free energy calculations for reference state for
> constant pH MD simulations...
>
> See the section "5.7.4 Topologies for free energy calculations" in Gromacs
> 4.6.5 manual.
>
>
>
> On Tue, Jan 28, 2014 at 3:09 AM, Ozbil, Mehmet <m.ozbil at umiami.edu> wrote:
>
> > Hello,
> >
> > I am trying to run constant pH MD with GROMACS, and started with the TI
> > free energy calculations. I am following Justin Lemkul`s free energy
> > calculation tutorial, and assuming that the free energy calculations will
> > be similar to calculate the protonation energy of titratable amino acids
> > such as GLU or HIS.
> >
> > My question is that, while scanning the lambda values for the free energy
> > calculations do I need to define both protonated and deprotonated states
> of
> > GLU in the same .top and .pdb file, or I just use one .top and one .pdb
> > file and by changing the lambda values from 0.0 to 1.0 it does the
> > deprotonation itself. If I need to incorporate the two states in one .top
> > and .pdb file can anyone help with how to do that?
> >
> > Thanks,
> > Mehmet Ozbil
> > --
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> >
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>
>
>
> --
>
>
>
> *--------------------Thanks and Regards,Bipin Singh*
> --
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*--------------------Thanks and Regards,Bipin Singh*
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