On 10/14/13 7:47 AM, Sathya wrote:
Hi,
I'm doing the KALP-15 IN DPPC through the Justin's tutorial
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin/gmx-tutorials/membrane_protein/03_solvate.html
I have few questions. Please help me to solve it.
1) After the topol.top file has generated from pdb2gmx is it necessary to
add DPPC 128 in the molecule section?.
If there are lipids in the coordinate file, there have to be lipids in the
topology. The tutorial walks you through all of this, step by step.
2) I have used DPPC 128 in the molecule section and during adding ions with
the following command shows error.
grompp -f ions.mdp -c system_solv.gro -p topol.top -o ions.tpr
The above command shows this error.
Fatal error:
number of coordinates in coordinate file (system_solv.gro, 27162) does not
match topology (topol.top, 33451)
Please tell me where should i change to solve this problem.
If you're adding ions, that means you should have already done the insertion,
inflation/packing, and solvation steps. You will not have 128 lipids at that
point (as is stated in the tutorial). You have a significant mismatch
somewhere, though, and the difference is nowhere close to being only a problem
with the lipids.
3) If i didnt use DPPC in molecule section of .top file while running
equilibration using make_ndx which ask us to enter the protein+lipids i
could not find the DPPC option there..
You don't make index groups from the topology; you make them from coordinate
files. If DPPC wasn't an option when running make_ndx, then you didn't have
lipids present. I believe this questions was just asked the other day.
Given the magnitude of problems you're experiencing, I would suggest starting
the tutorial over and checking your output at every step more carefully. There
seem to be some fundamental problems in whatever you have done.
-Justin
--
==================================================
Justin A. Lemkul, Ph.D.
Postdoctoral Fellow
Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 601
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201
jalem...@outerbanks.umaryland.edu | (410) 706-7441
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