On Jun 24, 2008, at 11:56 AM, Thomas C. Marlovits wrote:

Am using Chimera and would like to do the following: - would first like to focus on specific side chain residues (for example lysines) - at a specific atom of either one or all lysines present in my sample, I would like to draw a region of interest (which should be a sphere with a given distance ... then make it rather transparent like soap bobbles ...) ... the idea of this is to highlight areas within a given distance away from this atom - then I would like to read out all other side chains that are within such an area ( in a table or so) ... and eventually highlight them with specific colors ...

Elaine, is there an easy way to do this ? Tx, -Thomas ---------------------------------------------------------------------- ---------

Thomas C. Marlovits, PhD, M.A.S. IMP-IMBA Research Center - Research Institute of Molecular Pathology (IMP) - Institute of Molecular Biotechnology, Austrian Academy of Sciences (IMBA)

Hi Thomas, You can definitely (1) select the atoms or residues within a specified cutoff of some other atoms and write a list of what is selected to the Reply Log or to a file. Slightly trickier is (2) displaying a "bubble." (1) The following command selects all atoms within 4.5 angstroms of atom NZ in lysine 92, chain A (example structure 2gbp): select :92.a@nz za<4.5 to select the whole residues with any atom in the zone, use "z" or "zr" instead of "za", and to use all the atoms of that lysine, just omit "@nz" from the command. http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/ atom_spec.html#zones This selection process can also be done by Ctrl-clicking to select the atom and then using Select... Zone. You can write out a list of the selection with Actions... Write List (click Log if you want to send it to the Reply Log instead). The default is a list of all the atoms individually, but you can set it to "residues" instead to just get one line of output per residue. The command to do that same thing is "writesel" http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/writesel.html (2) The "bubble." I imagine something like Volume Eraser would be nice (check it out: Tools... Volume Data... Volume Eraser). However, that does not let you specify particular coordinates for the center. You have to move it around by hand. Volume Eraser really just makes a big atom and gives it a transparent color. You could add an atom in Build Structure (under Tools... Structure Editing), color it a transparent color, and change its radius with "vdwdefine" http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/editing/ editing.html#build http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/vdwdefine.html It doesn't let you enter specific coordinates for the atom. However, if you add the atom as a "new model" you can match it to different locations on the first. For example, if the new atom is model 1 and the structure of interest (say 2gbp) is model 0: rep sphere #1 colordef tpink 1 .6 .6 .6 color tpink #1 vdwdef 3.0 #1 vdwdef +1 #1 vdwdef +1 #1 match #1 #0:147.a@nz select #1 za<5 & #0 [... etc. ...] The radius would just be for display purposes. You'd still have to specify the zone distance when selecting. A couple of failed ideas: (a) You can make a spherical surface of specified radius with the command "shape" http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/shape.html but you cannot directly specify coordinates for the center or easily modify radius after it has been created. (b) Create a spherical object in BILD format. http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/bild.html Disadvantages are inability to make it transparent and having to delete/recreate the object just to change its radius. Best, Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html