Re: [chimera-dev] Save PDB and Map before fitting

Hi Pablo, I couldn’t quite puzzle out what you were saying below. In particular, I didn’t understand: "Then, I get the coordinates that are result from fitting "temporal.pdb" -- "mapY.ccp4" and move "chainX.pdb" opened in Chimera to these coordinates. But does not work fine.” So instead of trying to answer directly, I’ll just try to outline the principles involved and see if that helps. You open your map and your original PDB. Then you fit your PDB into the map. If you want to save the fitted PDB in the same coordinate reference frame as the map, then you need to take the transformed coordinates of the PDB, apply the inverse of the map’s transformation matrix, and use those coordinates. You don’t really say what API you use to save the PDB file, but you could just use the “write” command with the “relative” keyword to save the PDB file. Also, Midas.write(pdb_model, map_model, file_name) would do it. If you then open the map and new PDB file together they will be in their fitted orientation. Hope this helps, Eric Pettersen UCSF Computer Graphics Lab

On Apr 28, 2017, at 12:32 AM, Pablo Solar Rodríguez wrote:

Hello again!

Well, I've been testing the PDB saving in my plugin and it doesn't work as I expected. I'm gonna try to explain the best I know because maybe my theoretical concepts are wrong.

The aim of saving PDB is beacuse if I move (rotate and translate) my molecule on Chimera I need to save it before executing the exhaustive fitting to have the correct coordinates on disk. But when the process is finished and I move the molecule on Chimera to the fitting coordinates, it doesn't work properly. This not happens if I open the saved PDB and I execute the exhaustive fitting; in that case, the molecule moves correctly to the fitting coordinates.

I'm gonna explain it with the example.

1. Suppouse I have opened "chainX.pdb" and "mapY.ccp4" in Chimera and I move the molecule (uncheckin the 'A' in the model panel):

2. If I execute the exhaustive fitting in Chimera, the process will save "temporal.pdb" from "chainX.pdb" on disk. Then, I get the coordinates that are result from fitting "temporal.pdb" -- "mapY.ccp4" and move "chainX.pdb" opened in Chimera to these coordinates. But does not work fine.

3. However, If I open "temporal.pdb" in Chimera and I execute the process, it works fine.

Could be a desynchronization between the opened "chainX.pdb" in Chimera, the "temporal.pdb" saved on disk and the "mapY.ccp4"? I cannot see what could be happening...

I hope to have explained myself correctly.

Thank you so much in advance

Pablo Solar Rodríguez pablo.solar@delogica.com Delógica - www.delogica.com http://www.delogica.com/ España: C/Nuñez de Balboa 31, 2ª Planta - 2, 28001 Madrid, Tel.: (34) 91 431 31 09 Colombia: Edificio Torre Zimma - Carrera 15 88-70 Bogotá, PBX (571) 3000302

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El 27-04-2017 20:04, Pablo Solar Rodríguez escribió:

...

Hello Eric,

Thank you for the response. I will check it!!

Kind regards!

2017-04-26 19:28 GMT+02:00 Eric Pettersen mailto:pett@cgl.ucsf.edu>: Hi Pablo, Every model has an 'openState' attribute which in turn has a 'xform' attribute which holds the model's transformation matrix. A newly opened model, if it's the only model, will have the identity matrix as it's initial xform. If there are other models open, then its initial xform will be the same as that of the currently open model with the lowest ID number, in a "best effort" attempt to keep the newly opened model in the same frame of reference as the other models. So to see if you need to resave it you should compare the current xform to the one it had the last time you saved it. There is a trigger that fires when a model's transformation matrix changes — the 'OpenState' trigger will fire in the chimera.triggers trigger set, with the trigger data '.reasons' attribute containing 'transformation change'. However, there is a convenience trigger, chimera.MOTION_STOP, that you probably want to register for instead, that will collate all the many OpenState trigger firings that will occur during a mouse motion. That trigger is also in the chimera.triggers trigger set. If you aren't familiar with triggers, there is a programmer example about them:

https://www.cgl.ucsf.edu/chimera/current/docs/ProgrammersGuide/Examples/Main... https://www.cgl.ucsf.edu/chimera/current/docs/ProgrammersGuide/Examples/Main...

—Eric

Eric Pettersen UCSF Computer Graphics Lab

...

On Apr 26, 2017, at 12:41 AM, Pablo Solar Rodríguez mailto:pablo.solar@delogica.com> wrote:

Hello Elaine,

Thank you for the quick response. I'll check the info to find a way to do it. Just one more thing. Is there a manner to know when the map has been moved? Just to not resampling it each time needlessly.

Thank you!

El 25-04-2017 18:21, Elaine Meng escribió:

Hi Pablo, The map format doesn't include rotation information. You would have to resample it on a new grid to create a new map, such as with command "vop resample"... details here on saving maps after fitting (bottom of the page):

<http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/savemodel.html#afterfitting http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/savemodel.html#afterfitting>

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

On Apr 25, 2017, at 2:24 AM, Pablo Solar Rodríguez mailto:pablo.solar@delogica.com> wrote:

Hello Tom, Thank you for your quick response. I've checked the code in my plugin and the PDB saving works fine as I expected, even if I move the molecule.

My question is about saving the map. I tried to move it (rotate&translate unchecking the 'A' in the ModelPanel) and then save it with this code, but when I open the saved map, it is similar to the original one and does not keep the new coordinates. This could be a problem in my plugin, because I need to save them case of moving to get correct results in the fitting process.

So, how can I handle this situation? Is there any other way for saving the new map coordinates in the same way the PDB saving does? Hope I have explained myself correctly. Thank you in advance and kind regards, Pablo. _______________________________________________ Chimera-dev mailing list Chimera-dev@cgl.ucsf.edu mailto:Chimera-dev@cgl.ucsf.edu http://plato.cgl.ucsf.edu/mailman/listinfo/chimera-dev http://plato.cgl.ucsf.edu/mailman/listinfo/chimera-dev

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--

Pablo Solar Rodríguez

pablosolar.r@gmail.com mailto:pablosolar.r@gmail.com

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