Dear Chimera Users, I have a pdb file for an entire virus (biological assembly) that I can read into Chimera just fine, as either a multimodel PDB with 60 different models, or as a PDB lacking model and endmdl cards, but with the atom number of the multi-model pdb preserved. The model is placed very close to the density for the virus in a tomogram. When I use the fit in map command, the single model pdb moves nicely by a couple of nm and a few degrees into the tomogram density. For the multimodel map I must first use the combine command in the model panel to combine the 60 differernt models, but that then also moves nicely into the density. However, in both cases, when I try to write out the slightly rotated/translated coordinates to a PDB file, I wind up with a semi-corrupted PDB file containing **** in many locations, especially for the last half of the file. Since the virus is pseudo T=31 with 18 chains in the viral asu, the pdb model has more than 2 million atoms and 1048 chains; the chains obviously cannot be uniquely identified with a single letter, the atom numbers exceed the the allowed format, and residues are renumbered and then also exceed the allowed format. I can fix this by hand to some extent, and could write a jiffy to put it back into the multiple model format, but feel like there is a more elegant solution to this problem already embedded in Chimera. Preferably one that will allow high throughput down the road. Any advice would be appreciated! Thanks, Martin Martin Lawrence Department of Chemistry and Biochemistry Montana State University Bozeman, MT 59717 USA