Hi, I have a problem with a phosphate moving out of position during refinement. The complication is that there is an existing phosphate in the same location as the one I'm trying to place, but the existing one is part of a modified residue, and there is clearly density for the alternative conformation of the phosphate, but it is also clearly not still bound to the residue. How do I make sure that the phosphate does not move away from where it should be? Attached image show the phosphate more or less where I want it, and you should be able to see where the existing phosphate is attached to the residue. The large red density blob is where phenix.refine tried to put the phosphate last time. Kind regards, Chris ------------------------------------------------------- Dr. Christopher Wanty [email protected] Research Associate Biomolecular, Biomedical and Chemical Sciences, Building M310 University of Western Australia 35 Stirling Highway Crawley 6009 Western Australia Australia