On Mar 22, 2013, at 10:51 AM, Elaine Meng wrote:

Hi Chinh,
You can change torsion angles using the Adjust Torsions GUI (in menu under Tools... Structure Editing)
<http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/editing/editing.html#adjust>

... or the rotation command
<http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/rotation.html>

If you have lots of values, you would probably want to script it, but it probably wouldn't be that easy/convenient since the commands (or python, if you do a python script) will need to specify the 4 atoms used to define each torsion.

What Elaine says is absolutely correct.  What I would add though is that if the torsions you are changing are the phi, psi, or chi angles of standard amino acids, then adjusting them is somewhat easier since they are attributes of the residue and setting the attribute will change the torsion.  For example, to change the phi angle of residue 14.A to 90 degrees:

setattr r phi 90 :14.a

--Eric

                        Eric Pettersen

                        UCSF Computer Graphics Lab

                        http://www.cgl.ucsf.edu