Hi Root, It is described in the “preset” documentation: <http://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/menu.html#menupresets> … specifically, "Interactive 1 (ribbons) - shows most peptide and nucleic acid chains as ribbons, plus atomic detail (excluding hydrogens on carbon atoms) for residues within 3.6 Å of a ligand residue or metal ion. Atomic detail is also used for chains that are very short.” In other words, if the amino acid residue has any atom within 3.6 Å of what Chimera thinks is “ligand” or “ion” the whole sidechain will be shown, except any H atoms attached to C atoms. You do not need to search on the net, you can just look at the manual included with your download, using menu: Help… Search Documentation. For example, you could search for “presets” or “ribbon interactive preset”. The information you found is explaining something different: why the backbone atoms are not shown. I hope this helps, 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 Aug 17, 2016, at 11:13 PM, 郭尚哲 <b02b02049@ntu.edu.tw> wrote:

Hi all, I have some pdb files of ligand binding protein structures, and when I check these structures with the ribbon diagram (Presets -> Interactive 1 (ribbons)) with chimera, it not only show the "ribbon" but also the sidechain of some residues. I would like to know why, so I search on the Net. And I just find the site below: https://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/ribbonstyle/ribbon... It says "By default, when ribbon is shown for a residue, the mainchain atoms of that residue are hidden, except where bonded to other displayed atoms (such as the sidechain)." I can't get more imformation, and still don't understand. What is the rule chimera follow to show the sidechain of certain residues? Thanks, Root