Hi, I would like to generate an SA-omit Fo-Fc map for a ligand bound to protein. Using the GUI I selected the AutoBuild-Create Omit Map module and set the following : - data.mtz - protein.pdb (no ligand, no solvent) = start model - ligand.pdb (just ligand) = omit map atoms - omit map type = simulated annealing - omit region = omit around pdb The resulting map (/OMIT/resolve_composite_map.mtz) shows density for both the protein and the ligand. When I feed this into the CCP4 module FFT to generate an nF1-mF2 map (with n=1 and m=1) I still get density for both the protein and ligand. However I need only the ligand Fo-Fc density. What is the right way to do this ? Thanks, Tjaard Ing. Tjaard Pijning Research Assistant Protein Crystallography Group Nijenborgh 7 9747 AG Groningen The Netherlands (31)(0)50 363 43 85