I have a data set with high Rsym in the lower resolution ranges, and I don't understand what is going on.
The crystal diffracts to about 3.0 A and has large cell dimension ( space group P6522 a= 185., c= 360.) Mosaicity is low. I processed the data in P6522, solved the structure and refined it. The maps look good and the structure refines very well to R/Rfree of 20.5, 23.5%. But the dataset has a total Rsym of 22%, a redundancy of 20, an Rpim of 7.6%, and CC1/2 of 0.55 in the highest resolution shell. The problem seems to be in the lower resolution region around 8-5.5A. The Rsym there is around 20%, it actually has a bump in this resolution region and is slightly lower at 5.0 A before it steadily increases to higher resolution. The high Rsym region between 8-5.5 A correlates with very low I/sig which also increases again around 5.0 A and then steadily decreases. The diffraction image shows very weak spots too. My question is: Is it likely that the data are processed correctly and the crystal packing causes this strange diffraction pattern, or is there something wrong with the data processing or the crystal? Any suggestions would be greatly appreciated. Ursula -- Ursula Schulze-Gahmen, Ph.D. Assistant Researcher UC Berkeley, QB3 356 Stanley Hall #3220 Berkeley, CA 94720-3220
