Careina, I recommend to compare the quality of your data (Rmerge) to that of an average data set of same resolution. Do you have meaningful data to 2.3A resolution? Another possibility is the anisotropicity of your data. Try this server http://services.mbi.ucla.edu/anisoscale/, if the anisotropicity is significant.
Alex On Jul 13, 2011, at 8:38 AM, Careina Edgooms wrote: > Dear ccp4 bulletin board > > I just have a slight concern regarding my Rwork Rfree difference. I have a > structure that I have solved. I am reasonably content that it is complete > because it has refined well, it no longer has bad geometries and contacts and > all the rotamers, ramachandra, bond lengths etc are good. It gives favourable > scores on molprobity and procheck. My only concern is the R factor > difference. The resolution of the structure is 2.3A. The R factor is 0.24 > after refinement but the Rfree is 0.33 which seems to me to be rather high. > Should I be concerned? > > During refinement Rfree only drops from about 0.36 to 0.33 while the R factor > drops from 0.31 to 0.24.. I have removed automatic weighting in refmac in > order to constrain my bond lengths and angles during a couple of rounds of > refinement. This did not have any effect on the R factors, however. I am > fairly content that the space group I have chosen is correct so I am not sure > what else could cause the big difference in R factors? There is no twinning. > > Can I be satisfied that my structure is correct despite the high R free or > should I be doing other checks/ trying other things before I can submit this > structure? > > Thank you for any help > Careina
