Dear Sirs: I am modeling novel proteins on homologous structures from other organisms using SWISS-MODEL. After the model is completed I import the PDB file into Chimera to form disulfides and to produce publication quality graphics. I thought all was going well until I discovered that SWISS-MODEL was actually truncating one or both termini of my target sequences by 1-5 residues. In one case, I created the missing C-terminal tripeptide using MacPyMol, but MacPyMol will not not add the tripeptide to the C-terminus, because it is designed only to create intramolecular bonds. So I imported the protein and the tripeptide into Chimera. I selected the C-terminal oxygen of the protein and the N-terminal nitrogen of the tripeptide and tried to create a peptide bond using Build Structure>Adjust Bonds>Add Bond. Chimera claims that only one atom is selected, but in fact, both are selected. I do not want to try to build a tripeptide one atom at a time. Is there any way to do ligate the tripeptide? Thanks very much! Steve Aird Steven D. Aird Technical Editor Faculty Affairs Division Okinawa Institute of Science and Technology Graduate University 1919-1 Tancha, Onna-son Kunigami-gun, Okinawa-ken Japan 904-0495 Phone: 098-982-3584 Cell: 080-4154-9504 Email: steven.aird@oist.jp<mailto:steven.aird@oist.jp>