I have an incomplete pdb crystal structure of a homohexameric protein containing six ~25AA tails. In the incomplete model, two of these six tails are complete (A and F) and the other four are truncated at various positions (B,C,D, and E). I have used the either the A or F complete tails as templates and generated appropriate length segments to compleate each of the truncated B-E tails by selecting the appropriate residues and saving the selected atoms as a new PDB. Currently, I have all six tails completed and saved as a single PDB. I would like to use the Bond command to covalently link the extended chains, but my single PDB is segregated into models 1.1, 1.2, 1.3, 1.4, and 1.5. When I use the Bond command as follows "bond #1: 504.b@c & #1.3:505.a@n", I get an error that only one atom is selected. Does Chimera consider #1 and #1.1 to be different models? If so, how can I merge these 5 models into one to allow me to create the bond? Thanks, Jared -- Jared A. Godar Graduate Student: Stewart Lab Vanderbilt University Medical Center Department of Molecular Physiology & Biophysics 708 Light Hall 2215 Garland Ave. Nashville, TN 37232-0615 Work: 615.322.7898 Fax: 615.322.7236 jared.godar@vanderbilt.edu