It's radiation-damaged. Based on what did you say that it is not? Also, do you have ice rings or diffuse scattering which might be present in the higher-res shells in certain rotation ranges but not others, such as from solvent in the loop?
JPK From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Michael Jarva Sent: Thursday, May 18, 2017 7:48 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Optimising data processing of a I432 dataset with 75% solvent content. Dear all, I have a dataset that have two very interesting properties: a) It's in I432, and b) has a whooping 75% solvent content. You might think that the solvent content obviously is a big red flag, and so did I, but I have phased this successfully with just one monomer, and the packing result does makes a lot of sense. The resulting maps contain no extra umodelled blobs, and trying to phase it with an additional molecules does not give a good solution. The problem I have is that the diffraction intensity/Rmerge plummets/explodes around the 3.5Å mark (I assume because of the high solvent content) to such an extent that even though I have little radiation damage, 100% completeness in high resolution shells, and very high redundancy, any attempt to merge the dataset at a higher resolution has so far given no improvement to the maps. I'm hoping that there might be a few tricks out there I can apply to the spot finding/integration/scaling steps have it merge in a even slightly higher resolution than I currently have been able to do. Although I have a feeling that the only thing I can do is to grow another, much bigger, crystal... many thanks for any feedback /michael See below for sample outputs from aimless: Overall InnerShell OuterShell Low resolution limit 43.50 43.50 3.32 High resolution limit 3.10 8.78 3.10 Rmerge (within I+/I-) 0.079 0.010 21.891 Rmerge (all I+ and I-) 0.081 0.011 22.502 Rmeas (within I+/I-) 0.084 0.011 23.102 Rmeas (all I+ & I-) 0.084 0.011 23.169 Rpim (within I+/I-) 0.027 0.004 7.335 Rpim (all I+ & I-) 0.020 0.003 5.450 Rmerge in top intensity bin 0.010 - - Total number of observations 34917 1495 6448 Total number unique 2057 112 362 Mean((I)/sd(I)) 18.3 130.9 0.1 Mn(I) half-set correlation CC(1/2) 1.000 1.000 0.533 Completeness 99.9 97.4 100.0 Multiplicity 17.0 13.3 17.8 Overall InnerShell OuterShell Low resolution limit 43.50 43.50 3.84 High resolution limit 3.50 8.58 3.50 Rmerge (within I+/I-) 0.052 0.011 2.422 Rmerge (all I+ and I-) 0.056 0.012 2.659 Rmeas (within I+/I-) 0.055 0.011 2.553 Rmeas (all I+ & I-) 0.058 0.013 2.738 Rpim (within I+/I-) 0.017 0.004 0.804 Rpim (all I+ & I-) 0.014 0.003 0.644 Rmerge in top intensity bin 0.010 - - Total number of observations 24596 1690 6071 Total number unique 1462 120 343 Mean((I)/sd(I)) 25.8 132.0 1.0 Mn(I) half-set correlation CC(1/2) 1.000 1.000 0.771 Completeness 99.8 97.6 100.0 Multiplicity 16.8 14.1 17.7
