errabah fatima ezzahra wrote:
I am sorry to be asking you again but do you start with different
velocities by changing the temperature that will lead to change in
velocities, i ma new to Gromacs so i dont know where to change he
velocities, i checked the mdp file and i didn't see any velocity
Keep the temperature the same and change gen_seed.
-Justin
thank you
Fatima ezzahra
------------------------------------------------------------------------
*De :* Justin A. Lemkul <jalem...@vt.edu>
*À :* Discussion list for GROMACS users <gmx-users@gromacs.org>
*Envoyé le :* Jeudi 7 Juillet 2011 14h55
*Objet :* Re: Re : Re : [gmx-users] Re: Hexamer problem/ The N and C
termini of peptides
errabah fatima ezzahra wrote:
> *
>
> hello
> Does anybody knows why The N and C termini of peptides can be
neutralized before running simulation of peptides ?? i read this some
where in a research paper , they dont say why but they do that using
acetyl amine groops. Probably to evoid the repulsive interactions
between the end of the peptides , please correct if i am wrong as my
chemistry is not good, my one trimer is made of 3 peptides that ends
with GLU LEU LEU and the other trimer ends with is LEU GLU LEU , should
i worry about neutralizing the c and N termini
>
Capping groups can be added to termini using different software
programs. There is no utility in Gromacs to do so. Once built, choose
'None' for the termini when running pdb2gmx to build a normal peptide
bond between the terminal residue(s) and capping group(s).
Such groups are often added (1) if artificial terminal attraction or
repulsion should be avoided or (2) if the modeled peptide is a segment
of a longer polypeptide or protein, in which case such integral charges
are an incorrect representation of reality.
> Also what the important of running 20 simulations of the same 6
peptides ???. is that to compare the 20 simulation results and see ****
which give better simulation sorry if my question are something i should
know. i am trying to find how to get six peptides to self assemble to a
hexamer . i will really appreciate your answers.
>
Running multiple simulations of a given configuration (using different
starting velocities) gives better sampling. You can't conclude anything
from a single trajectory. Just as you wouldn't run a single experiment
on the bench and call it conclusive, so too is it true of simulations -
if you run just one simulation, how do you know you're not seeing the
one outlier in the data set?
-Justin
-- ========================================
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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--
========================================
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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