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Hello everyone, I have a few crystals to be x-rayed next week. Before that I hope to get a clear idea about what I am doing (I am new to anomalous scattering). Facts: 1. The crystal is a protein co-crystallized with a ligand 2. The protein structure is known. 3. The ligand has a heavy atom bromide (absorption K-egde=13.47Kev) 4. Data resolution is ~3 angstrom Goals: 1. Locate the bromide position 2. Locate and refine the ligand Questions: 1. Do I need to carry out MAD experiment at 3 wavelengths or there is some other easier way since the protein structure is known (I am not expecting big change of the protein structure itself)? 2. Assuming I have the MAD data, what should I do next using phenix to achieve the two goals listed above? Here are some thoughts: - Using phenix.hyss to locate the anomalous scatterers - Using phenix.autobuild to build the protein model (which data set to use?) - Using coot to add ligands to the protein structure (Is the relative position between the protein and the ligand known based on phenix.hyss and phenix.autobuild?) - Using phenix.refine to refine the ligand+protein complex Thank you all for reading this. ====================== Jason Structural Biology Department University of Pittsburgh ======================