Dear colleagues, I am dealing with the refinement of a protein with 5 monomers in the asymmetric unit at 2.2 Å resolution. Four of them have correct geometry and good density map, however, the fifth molecule has poor density and bad geometry. Ramachandran plot is presents 91.05% (favored), 3.23 % (outliers). I have modified the occupancy of the molecule, the refinement results in 0.8 occupancy for this chain. I also tried to refined the structure without this chain, but the R values increased and the density map indicated that it should be there. I would like to refine this chain fixing the geometry of the others which are correct. Do you have any ideas about how to proceed? Some info: Protein residues 305 5 monomers in the a.u Space group C121 a=151.390, b= 67.81, c=155.420Å, 94.53º R value 0.23 / Rfree 0.28 Many thanks, Noelia Noelia Bernardo García, PhD Instituto de Química Física "Rocasolano" Spanish National Research Council (CSIC) c/ Serrano 119 28006 Madrid (Spain) Phone: +34-91 561 94 00 (ext. 961107) e-mail: [email protected]