Do the following. 1) Perform density modification (NCS averaging and solvent flattening) 2) Run the new phases through a model building program (Buccaneer works for all resolutions, Arp/wArp works well for better than ~2.7 Å or better resolution)
If this doesn’t give you a better quality model (meaning one that has identifiable secondary structure and an R-free below about 45%), then you need to go back to square one and examine your assumptions regarding data quality, Laue symmetry and space group, MR solution, etc. Diana ************************************************** Diana R. Tomchick Professor Departments of Biophysics and Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Blvd. Rm. ND10.214A Dallas, TX 75390-8816 diana.tomch...@utsouthwestern.edu<mailto:diana.tomch...@utsouthwestern.edu> (214) 645-6383 (phone) (214) 645-6353 (fax) On Nov 17, 2017, at 2:23 PM, Yue Li <000017ef008f608c-dmarc-requ...@jiscmail.ac.uk<mailto:000017ef008f608c-dmarc-requ...@jiscmail.ac.uk>> wrote: Dear all, I have several datasets (one best resolution reaching 2.2A), giving C2 space group, two molecules in an asymmetry unit (65.1% of solvent content). When running MR using a template (<20% sequence identify to the target molecule), I got a solution with high TFZ (23.7) and LLG (842). However, the Rfree sticks to 50% in the structural refinement using phenix. There is no complain in Xtriage - no twin, no translational NCS. I think that the structure solution looks reasonable, which can explain the three disulfide bond formations through the sequence threading. I tried to search three molecules in the asymmetry unit, but the final solution gives me two molecules. Do you have any suggestion for this high Rfree problem? Thank you very much for your help. All the very best, Simon ________________________________ UT Southwestern Medical Center The future of medicine, today.
