Sorry for an easy question. Chimera has a hook to use a local mirror of the PDB (preferences-PDB) I am too thick to see what path to give it. If you have the PDB, you have the top level /blah/blah/pdb the structure directory /blah/blah/pdb/data/structures/all and the divided directory /blah/blah/pdb/data/structures/divided/pdb When a non-python reader looks at the code (__init__.py), it seems to be trying out the divided directory IDcode = IDcode.lower() subpath = IDcode[1:3] + os.sep + "pdb" + IDcode + ".ent" pdbDir = systemPDBdir() if pdbDir is not None: ..... but this does not look correct. The PDB divided path would want subpath IDcode[1:2] to get the subdirectory "pt" from a file like "5pti" Many thanks and sorry for a seemingly daft question. -- Got No Time? Shop Online for Great Gift Ideas! http://mail.shopping.com/?linkin_id=8033174