[Chimera-users] simple question

I should be able to find this but haven't looked too hard. I am interested in a salt bridge between the C-terminal carboxylate and a Lys residue in the protein. I know how to visualize the Lys side chain, and the C-terminal residue. How do I visualize the carboxylate terminus? I tried backbone only actions, but nothing worked. Thanks AGSzabo