Hi, I am working on a 2.4 angstrom structure that is in its final stages of refinement and finding that REFMAC5 is giving a large difference between R and Rfree (10%), 0.16 and 0.29, respectively. 2Fo-Fc maps looks great and there is very little density in the difference maps. My model covers the entire protein sequence, except for ~5 residues on N-term and 3 residues on C-term. I then used the model for refinement (annealing) within CNS, and found that R and Rfree are relatively similar, 0.2 and 0.28, but in better agreement.
I have read other posts addressing similar questions, but still unsure what my problem could be, if there is one. While I don't mind repeating things in CNS, I would really like to learn to be completely reliable on CCP4 Suite as much as possible, since i really like the REFMAC5 - Coot duo. I would appreciate any suggestions or comments you might offer. Given how nice the density maps look and that the model passes procheck analysis with very few suggestions for further investigations, i am unsure when to go from here. Thanks in advance for all feedback! Cheers, Nick
