Dear GIA, In addition to the anisotropy, I would also check your diffraction images and make sure that there are no (even hardly perceptible) ice rings present. Depending on how the data processing software handled this, they may cause high Rfactors in the range you mentioned.
Best, Herman Von: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] Im Auftrag von Gianluca Cioci Gesendet: Freitag, 13. Oktober 2017 10:30 An: CCP4BB@JISCMAIL.AC.UK Betreff: [EXTERNAL] [ccp4bb] High R/Rfree after MR Dear All, I am trying to refine a structure at 3.3A. Model has 60% identity to the target. Maps look OK (for 3.3A) and rebuilding in Coot is relatively straightforward. However, after some rebuilding cycles the R factors are stuck at 0.37/0.39 (REFMAC). XTRIAGE tells me that everything is normal (no twin, 98% completeness, R=3.5% in the low resolution bin), perhaps some anisotropy is present. I have already refined 2 homologous structures at resolutions going from 3.2 to 3.8 and there were no problems (final R ~ 0.21/0.24). Any advice ? Thanks, GIA