Hi Miguel, For creating the volume occupancy map the molmap command creates a volume by placing a Gaussian centered at each atom. http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/molmap.html The Gaussian width is set by the molmap resolution parameter and is the same for all atoms. It does not use vdw radii. If you want to use vdw radii and if you want to sum over many torsion angles you might use a modified version of the molmap Python code. See the molecule_grid_data() routine in file chimera/share/MoleculeMap/molmap.py in your Chimera distribution. Tom

Hi Eric and Tom,

Thank you! Yes, I would like to improve the script so, it would be great if you can give me pointers about clashes and filling the VDW space!

Also, just a question: is there a way to access bonds as part of a tree? I would like to select the atoms implicitly from the list of bonds to be rotated.

Best regards,

Miguel

Le 13 mai 2010 à 02:15, Eric Pettersen a écrit :

...

Hi Miguel, The script still is pretty useful! I've added it to the "Python Scripts" page on our wiki (Scripts – Chimera <http://socrates2.cgl.ucsf.edu/trac/chimera/wiki/Scripts>). You are right that improvements could be made, but it's a nice starting point. If you ever decide to refine the script, I could probably provide pointers on finding clashes, whereas Tom Goddard (whom I've cc'ed) would probably have to be the one to assist in filling a grid based on the atom's VDW radius (presumably scaling a three-dimensional gaussian or some such).

--Eric

On May 12, 2010, at 1:46 PM, Miguel Ortiz Lombardia wrote:

...

Le 12 mai 2010 à 19:00, Eric Pettersen a écrit :

...

Hi Miguel, I'm glad you got everything sorted out. Good luck. Feel free to shoot me any further questions you might have.

--Eric

Hi Eric,

Thanks! I managed to make it work. I'm attaching the script in case you or someone may find it useful. There is only a point I haven't managed to solve: as it is, the script creates a grid point at the atom center positions, while I would be more interested in the van der Waals volume. Nevertheless, since this is a very naive approach (it would be more interesting, for example, to avoid any clashes) I'm using an external set of programs (mapman and mama from the "Uppsala Software Factory") to extend this volume by a couple of grid points.

I'm attaching as well a figure so you see how it looks like (after expansion with mapman/mama).

Thanks for your advice, I have learnt a lot from this exercise.

Best regards,

-- Miguel

Architecture et Fonction des Macromolécules Biologiques (UMR6098) CNRS, Universités d'Aix-Marseille I & II Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France Web: http://www.pangea.org/mol/spip.php?rubrique2

<C3vol.png><torspace.py>

-- This message has been scanned for viruses and dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is believed to be clean.

-- Miguel

Architecture et Fonction des Macromolécules Biologiques (UMR6098) CNRS, Universités d'Aix-Marseille I & II Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France Web: http://www.pangea.org/mol/spip.php?rubrique2