Hi Francesco, I don't know if Eric already said this, but you have to use Chimera version 1.5 (daily build) to have the "define centroid" capability, it is a fairly new feature. what's new in 1.5: <http://www.cgl.ucsf.edu/home/meng/docs/relnotes/snapshot.html> current (1.5) documentation for "define": <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/define.html> If you are already using a recent 1.5 build, then maybe there is some small error in how you are typing the command. Besides looking at the man page above, you can also try just typing it in on the Command Line before you put it in a per-frame script. Best, 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 Mar 9, 2010, at 2:45 PM, Eric Pettersen wrote:
On Mar 9, 2010, at 2:17 PM, Francesco Pietra wrote:
Hello Eric: I have seen your later correction mail.
I had a bad day, that is little time for chimera and with little success. Please try to guess were I was faulty.
francesco@tya64:~$ chimera --version chimera alpha version 1.5 (build 30193) 2010-03-06 09:27:34 GMT francesco@tya64:~$ This is amd64, at the moment I have no 32bit computer.
<select ligand> selects too much.
<select :residue.number> <select :residue.name> do select exactly what I want (which is a small ligand of HEME ligand of the protein.
The problem was with <define> command
MD-movie...Per-Frame "define centroid :residue.number" ... Apply
then activating the movie gave the same view as not going through the Per_Frame, i.e., the small ligand does not leave any sphere on the path. I did not investigate if the sphere are too small to be seen at the magnification I used, ore have the same color as the background (black). Very likely, I did some other major mistake.
Not sure what to say. Works for me. I've appended an image of centroids tracing the motion of a small ligand in an RNA binding site. I used a step size of 10 and this 'define' command:
define centroid raiseTool false radius 1.0 color goldenrod sel
"raiseTool false" prevents 'define' from trying to bring up the Axes/ Planes/Centroids tool (and update that tool's table) for every centroid created. The other options control the size and color of the centroid. I had the small ligand selected so 'sel' is my atom spec. I tried it a second time with ":35" (which also selects the small ligand) and that worked too.
FYI, "~define" will get rid of all the centroids.
I hope this helps somehow. Are you sure you had the "Interpret script as" part of the per-frame dialog set to "Chimera commands"? I can't imagine that you didn't, since you would have gotten some kind of error if it had been interpreted as Python.
--Eric