Hi Elaine, Thanks for all the answers you give to our questions. They are very helpful as I learn more everyday. I have a question. Is there anyway to rename a chain in a PDB file through the GUI? I have a few PATCHDOCK generated PDB files with two different chains named under Chain 'A' as #0.1 and #0.2. When I try to get the list of hydrogen bonds between these two chains, the chain name 'A' appears for all of the h-bonding pairs. So, I want to have them named Chain A and Chain B for easier analysis than scratching my head figuring out which h-bond pair is between the chains or with in the chain. I am attaching the pdb file. Please help me. (I thought of renaming the chains in the PDB file going through the PDB header (text file) and manually changing the name. But I am not a expert if anything goes wrong.) Sincerely Hari