Dear All,I have a theoretical/practical question about omit maps and refinement. I am completing the refinement (in Phenix) of a protein-ligand complex at 1.3A resolution. I solved it by MR and automatic rebuilding of the protein alone first then built in the ligand. Rfree and Rfac are 19.4%/18.2% after TLS and water-picking in Phenix. The model includes everything protein, water, ligand and some ions. However I have some slight doubts one region in my ligand. What would be the best map, less biased, to look at this "very late" stage of the refinement. Are composite or systematic SA omit map useful options at this stage ? Thanks a lot in advance Pascal F. Egea, PhD Assistant Professor UCLA, David Geffen School of Medicine Department of Biological Chemistry 314 Biomedical Sciences Research Building office (310)-825-1013 lab (310)-825-8722 email [email protected]