Hi George, Two issues: (1) You have to also display the atoms, e.g. display sel (or menu: Actions... Atoms/Bonds... show) (2) If there is ribbon, by default it suppresses display of the backbone atoms, so you could either hide ribbon (e.g. Actions... Ribbons... hide) or use the command "ribbackbone" to allow showing both ribbon and backbone atoms at the same time. <http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/ribbackbone.html> 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 May 26, 2012, at 6:07 AM, George Tzotzos wrote:

This must be really trivial but I am asking nevertheless as I tried to no avail.

I'm trying to visualise the terminal carboxylate oxygens. For example, I do:

select :125@O :125@OXT and get 2 atoms selected. I then try to Actions Atoms/Bonds sphere. Nothing is shown.

I would be grateful for any suggestions Regards George