[Chimera-users] Atom Specification not working in exported PDB

[Elaine Meng]

Hi Gustaf,
After reading the exported PDB file back into Chimera, it works to use residue number if you also specify het chain, e.g.

show :17.het

I’m not sure exactly why (maybe a bug), but it’s probably related to the unexpected case of all the atoms being HETATM  rather than ATOM because there are no standard residues in your system.

I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.                       
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco


> On May 30, 2018, at 11:54 PM, Gustaf Olsson <gustaf.olsson at lnu.se> wrote:
> 
> Hello again Elaine
> 
> With regards to the atom serial number, yes this did work and I am now able to select a molecule by atom numbers, though this is not very convenient.
> 
> With regard to the residue selection, no. It works on my original PDB file used to set up the simulation, it works on my loaded trajectory file though it does not work on my exported PDB file.
> 
> From what I can guess it has something to do with the format of the exported PDB file though I cannot figure out why chimera cannot find residue 17 in a PDB file, correctly numbered, that it produced itself. I might just need to modify my selection syntax though I can’t see why.
> 
> You should have received an invite to a shared BOX volume containing the files needed to (potentially) reproduce this issue. If you’d prefer I post a shared link here, pleas let me know. This is what I observe on my end:
> 
>    -> AMBER MD simulation
>        open /amberSimulationFiles/filesRead.py    # Just loads prmtop and mdcrd
>        show :17    # Works
> 
>    -> PDB used to prepare amber input
>        open packmolPDB.pdb
>        show :17    # Works
> 
>    -> PDB exported from Chimera
>        open chimeraExportedPDB.pdb
>        show :17    # Does not work
> 
> Any help solving this would be greatly appreciated of course.
> 
> Best regards
> // Gustaf
> 
> 
>> On 30 May 2018, at 17:58, Elaine Meng <meng at cgl.ucsf.edu> wrote:
>> 
>> Hi Gustaf,
>> I have every expectation that you should be able to refer to the residue by number, e.g.
>> 
>> show :17
>> ~show :17
>> 
>> …or by atom serial numbers, e.g. (your syntax was wrong):
>> 
>> show @/serialNumber>535 and serialNumber<594
>> 
>> It should be the same as when you have the original trajectory open.  Can you use “show :17” in that case?  We would need an example of your trajectory input to see how Chimera is interpreting it.
>> Best,
>> Elaine
>> -----
>> Elaine C. Meng, Ph.D.                       
>> UCSF Chimera(X) team
>> Department of Pharmaceutical Chemistry
>> University of California, San Francisco
>> 
>>> On May 30, 2018, at 4:33 AM, Gustaf Olsson <gustaf.olsson at lnu.se> wrote:
>>> 
>>> Hello again Chimera Users
>>> 
>>> So now that I have the “movie” command working decently, it turns out that I cannot export a PDB file from my MD simulation and retain the ability to select by residue or atom number.
>>> 
>>> PDB files generated by other software (PACKMOL, AMBER) works fine though when I exported a PDB file from a fram in an AMBER MD simulation using chimera, I can open the file, I can select using residue names though trying to refer to atom or molecule numbers does not work. To be clear, the exported PDB file contains multiple molecules and solvent, all ar present and the file loads though trying to run commands like
>>> 
>>> show :17
>>> ~show @536-593
>>> 
>>> Affects EVERY atom and molecule in the system when it should only affect residue 17 (by specifying residue number OR all atoms in that residue). Using the
>>> 
>>> show :XXX
>>> 
>>> works as intended though this affects all residues XXX and I only want to affect residue 17.
>>> 
>>> Am I doing something wrong or can I solve this in a simple way?
>>> 
>>> Best regards
>>> // Gustaf
>> 
> 
> 
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