For MMPBSA.py calculations, explicit solvent molecules are never used for
the calculation. MMPBSA.py removes the solvent before doing any
calculations. So if you give it a trajectory (or multiple trajectories)
without water molecules along with a dry/stripped topology, the calculation
will be the same, but MMPBSA.py just won't have to remove the water atoms
first.
In this case, you do not need to specify anything for the strip mask. If
you don't give MMPBSA.py a solvated topology file, it knows not to strip
any residues from the trajectory.
You can use the startframe variable in the &general namelist to specify
what frame you want the calculation to start on. And I believe that is for
each trajectory if you provide more than one.
-Bill
On Wed, Mar 4, 2015 at 9:48 AM, James Starlight <jmsstarlight.gmail.com>
wrote:
> and some additional questions:
>
> 1- what should be provided in the mmgbsa.input file for the stripped
> mask in case when I use already stripped from the solvent trajectories
> 2- how it possible not to take into the analysis x fist snapshots from
> each processed trajectory used within one mmgbsa calculation?
>
> James
>
> 2015-03-04 15:10 GMT+01:00 James Starlight <jmsstarlight.gmail.com>:
> > Hi Bill,
> >
> > so I'd like to specify more:
> > mmgbsa.py accept *several* input trajectories files (specified after
> > its -y flag) each of which should consist only of the atoms for ligand
> > and receptor as well as stripped topology with the same atoms isn't
> > it? so for calculation of the free energy of binding and its
> > decomposition the presence of solvent within the system is not needed?
> >
> > Regards,
> >
> > James
> >
> > 2015-03-03 16:23 GMT+01:00 Bill Miller III <brmilleriii.gmail.com>:
> >> You will need to strip all the water molecules out of the trajectories
> >> using cpptraj prior to running MMPBSA.py since they all have different
> >> numbers of water molecules, and then use the dry prmtop and just don't
> >> provide a solvated prmtop. You don't have to merge them all into one
> >> trajectory using cpptraj prior to running MMPBSA.py. You can just use a
> >> wild card or just list them all after the -y flag in the MMPBSA.py
> command.
> >>
> >> I hope that helps.
> >>
> >> -Bill
> >>
> >> On Tue, Mar 3, 2015 at 6:58 AM, James Starlight <jmsstarlight.gmail.com
> >
> >> wrote:
> >>
> >>> Dear Amber users!
> >>>
> >>> I'm going to perform per-residue decomposition analysis for several
> >>> protein-ligand systems having 3 independent trajectories for each
> >>> system. I wounded to know
> >>> 1) is it possible to include several trajectories tax the standard
> >>> input to MMPBSA.py or alternatively I should to merge all trajectories
> >>> for the same system together using cpptraj?
> >>> 2) what I should do if some of the trajectories for the same system
> >>> are consisted of different number of atoms (and its parm7 files also
> >>> differs)-> because each time each system has been solvated de novo->
> >>> so the number of solvent molecules in identical protein-ligand systems
> >>> are differs. In these regards Is it possible to i) strip all solvent
> >>> using cpptraj from each trajectory and ii) to join all of them
> >>> together ( consisted of only protein-ligand atoms) iii) to provide
> >>> stripped parm7 file for the MMPBSA.py as well as the stripped
> >>> trajectory.
> >>>
> >>> I would be very thankful for any other solutions,
> >>>
> >>> James
> >>>
> >>> _______________________________________________
> >>> AMBER mailing list
> >>> AMBER.ambermd.org
> >>> http://lists.ambermd.org/mailman/listinfo/amber
> >>>
> >>
> >>
> >>
> >> --
> >> Bill Miller III
> >> Post-doc
> >> University of Richmond
> >> 417-549-0952
> >> _______________________________________________
> >> AMBER mailing list
> >> AMBER.ambermd.org
> >> http://lists.ambermd.org/mailman/listinfo/amber
>
> _______________________________________________
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>
--
Bill Miller III
Post-doc
University of Richmond
417-549-0952
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Received on Wed Mar 04 2015 - 08:00:02 PST
