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Bug #1278

Wrong topology update after genbox solvation

Added by Oliver Schillinger about 7 years ago. Updated over 6 years ago.

Status:
Closed
Priority:
Normal
Category:
preprocessing (pdb2gmx,grompp)
Target version:
Affected version - extra info:
4.6.2
Affected version:
Difficulty:
uncategorized
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Description

Hi,
I have a system with one protein chain, a ligand and 3 important tip4p water molecules near the active site, with residue names "HO4" in the .gro file and listed as "SOL 3" in the .top file.
I solvated my system with genbox, adding, say, 10000 water molecules. These are properly added to the .gro file with residue name "SOL".
Here comes the problem:
When genbox updates the .top file I expected it to either append the newly generated water molecules as "SOL 10000", or to update the present SOL entry to "SOL 10003" in order to match the total number of waters present.
What happens though is that genbox appends a new SOL entry to .top: "SOL 9997" so that now the total number of SOL molecules matches only the number of newly generated waters, regardless of the fact that there were already 3 present.
This creates an inconsitency in atom numbers in .gro and .top that is detected by grompp.
It is rather an inconvenience than a bug, but on a calm day you might consider changing the behaviour of genbox as it might save some users some time.
Cheers,
Oliver

History

#1 Updated by Pedro Lacerda about 7 years ago

I can reproduce your case, but your structure doesn't match the topology, ie HO4 in .gro and SOL in .top. Try rename HO4 to SOL and post the results.

But maybe I'm wrong and you should wait somebody more involved to point a better direction.

#2 Updated by Oliver Schillinger about 7 years ago

Dear Pedro.
Renaming the residues to SOL seems to resolve the problem.
The residue names had been generated by pdb2gmx from a pdb structure.
I liked it at first as I can then refer to only these 3 waters I kept from the PDB as "resname HO4" in vmd.
I guess that's where the inconsistency stems from.
Cheers,
Oliver

#3 Updated by Pedro Lacerda about 7 years ago

Oliver, you can refer to these waters using their residue id. I don't know why pdb2gmx generated these names. I hope this helps.
cheers =)

#4 Updated by Rossen Apostolov over 6 years ago

  • Status changed from New to Closed

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