Dear Phenix BB, We have a 15 aa circular peptide. It has numerous non-natural amino acids, including 1-2 that aren't in the PDB anywhere. Where have created a cif file that allows Phenix refine to run without craching, but I am not sure I am doing it right, and it was kind of complicated. I was wondering if there was anyone out there with ample experience with this type of thing that could help us check over our cif and more importantly recommend the best way to make these cif files in the future. Thanks, Dr. John B. Bruning Head, Laboratory of Protein Crystallography and Structural Biology Associate Professor Oracle For Research Fellow Institute of Photonics and Advanced Sensing School of Biological Sciences, Discipline of Molecular and Biomedical Science Faculty of Sciences, Engineering and Technology The University of Adelaide Adelaide, South Australia 5005 Telephone: +61 08 8313 5218 Email address: [email protected]mailto:[email protected]