Reprocessing data to lower resolution only helps if there are ice rings or other sources of non-desired diffraction that can be eliminated as contributors to learned profiles in profile fitting. Strong ice diffraction occurs at 2.28A and 2.68A, so there is no indication that reprocessing data to lower resolution will change anything other than overall R-merge and other R-statistics. To calculate these statistics it is enough to re-merge the data with lower resolution.
Zbyszek Otwinowski > Hi all, > > This is a basic question and I'm sure the answer is widely known, but > I'm having trouble finding it. > > I'm working on my first structure. I have a dataset that I processed > in XDS with a resolution cutoff of 2.35 A, although the data are > extremely weak-to-nonexistent at that resolution limit. After > successful molecular replacement and initial refinement, I then > performed "paired refinements" against this dataset cut to various > resolutions (2.95 A, 2.85 A, 2.75 A, etc). Based on the improvement > in R/Rfree seen between successive pairs, it appears that the data > should be cut at around 2.55 A. > > Here is my question: as I proceed with refinement (I'm currently using > Phenix), should I now simply set "2.55 A" as the resolution limit in > Phenix? Or should I go back to XDS and actually reprocess the data > with the new limit (2.55 A instead of 2.35 A)? > > Thanks, > Tom > Zbyszek Otwinowski UT Southwestern Medical Center at Dallas 5323 Harry Hines Blvd. Dallas, TX 75390-8816 Tel. 214-645-6385 Fax. 214-645-6353
