Hi All, Indeed even the latest COOT still relies on the old PDB format and hydrogens fly. Its probably not prudent to use hydrogens in refinement then remove them and add back each time. Kind of defeats the purpose of using them in the first place. Until COOT is updated I found a pretty easy way around things as long as you have access to the internet. Just use the MOLPROBITY site (http://molprobity.biochem.duke.edu/). In addition to it being a fantastic tool for really cleaning up structures, you can quickly upload your refined file from Phenix with hydrogens, then hit the button to downgrade to PDB v23. It creates the appropriate file with renamed hydrogens that work great in COOT. You can then re-upload the COOT rebuilt model and it will "upgrade" naming to the latest PDB version. Download that file and there you go for Phenix refinement. Sounds like a bit but very fast and easy to implement until COOT is upgraded. Joe ___________________________________________________________ Joseph P. Noel, Ph.D. Investigator, Howard Hughes Medical Institute Professor, The Jack H. Skirball Center for Chemical Biology and Proteomics The Salk Institute for Biological Studies 10010 North Torrey Pines Road La Jolla, CA 92037 USA Phone: (858) 453-4100 extension 1442 Cell: (858) 349-4700 Fax: (858) 597-0855 E-mail: [email protected] Web Site (Salk): http://www.salk.edu/faculty/faculty_details.php?id=37 Web Site (HHMI): http://hhmi.org/research/investigators/noel.html ___________________________________________________________