Hi Andrei, I believe that it is already ribbon when you open it, but if not, use "Presets... Interactive 1 (ribbons)" or "Actions... Ribbon... Show." By ribbon/worms we mean a smooth path through the CA atoms, instead of the CA trace, which is just a series of bonds between CA atoms and looks like a zig-zag. Probably you mean that the ribbon is just a tube of constant width and does not show secondary structure (where helices and strands are wider parts of the ribbon, and there is an arrowhead at the end of each strand). That is because the structures does not have HELIX and SHEET information at the beginning. You *can* show the ribbon like that, but you would have to figure out yourself which residues are helix and strand, and make the assignments yourself. This can be done using the Selection Inspector, Define Attribute, or the command "setattr," for example setattr r isHelix true :1-10.a,23-36.b setattr r isSheet true :15-19.a,23-29.a For details on manual assignment, see methods A, C, D, and E in this previous post: http://www.cgl.ucsf.edu/pipermail/chimera-users/2007-April/001514.html Method B uses the "ksdssp" in Chimera to calculate secondary structure, but this method cannot be applied to CA-only structures. I hope this helps, 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 On Oct 4, 2009, at 12:52 AM, Andrei Neamtu wrote:

Hello, Just a quick question:

I have downloaded the latest daily build of CHIMERA and I want to make a ribbon picture only fom the alpha-Carbon trace. On the site it is said in the Appearance and Image-Saving section that "CA-only and P-only structures can be shown as ribbons and worms "

I tried but didn't succeded . Does anybody know what are the steps in displayng such a structure? Andrei