Dear all, I have a particular problem... so, I have a beautiful crystal with nice diffraction pattern at 2.7A. The diffraction images are composed by very strong spots and weak spots. With XDS, if I collect all spots I get good map, but it is impossible to solve the structure by molecular replacement. If I collect only the strongest spots (STRONG_PIXEL= 99), I'm able to solve a very good structure... My problem is: I was trying to get the apo-structure of my protein. I obtained nice crystals of the "apo-protein", but using the method above, in the structure I have found also the ligand!! (probably incorporated during the overexpression). My protein is a multimer and, biochemically, I found that the endogenus ligand bond to the protein is in the ratio 1:6. ...and I got a crystal in this way.
So, is there a way to analyze all spots in the diffraction pattern to have a structure of the apo-protein? Is a good idea discard the strongest spots and try to analyze only the weak spots? If yes, how I can do it? All the best, Marco
