Dear All, I am refinining a protein-NAD complex structure at ~1.9A resolution. I have included a main conformation for my NAD ligand but while I see clearly the position for the nicotinamide- first ribose part, my density bifurcates when it comes to the second ribose-adenine. It seems that I have two (at least) conformations for this part of the ligand molecule. Can I refine these two alternate conformations in Phenix knowing that a part of the ligand will be common (have an occupancy of one) while the two other ones will be separate? Do I need to enter two ligand molecules or do I have to do more elaborate things? Last question is it possible that for the variable regions I may end up with a sum of occupancies that is not 1 while for the fixed region it might end up being one? That's three questions for the wizards. Thanks in advance. Pascal Egea UCSF