Re: [ccp4bb] weird diffraction pattern
Hi, Thanks to all who gave me suggestions concerning the weird diffraction pattern and I really appreciate it that Kay Diederichs help me processing my data set and answer my questions. Although the data set can be processed using HKL3000, XDS without problems, the Rwork/Rfree values are still above 0.5 after molecular replacement. There can be several reasons. 1) The structure change a lot after binding DNA, so it is not possible to find a solution using molecular replacement. 2) Strong radiation damage and 1.0 degree image widths prevent good integration results. It may be better to use 0.1 degree image widths. 3) Streaky spots appearing in certain directions because of anisotropy or lattice translocation disorder, or one very large unit cell dimension lying along the X-ray beam may also have an affect on data processing. Now I am optimizing the crystals to address these problems. Best wishes and thanks again for your help, Chenjun Tang
Re: [ccp4bb] weird diffraction pattern
Hi Jacob, I have tried seeding approaches but it didn't help. All best, Chenjun Tang
Re: [ccp4bb] weird diffraction pattern
Hi David, Thanks for your comments. Although the spots become streaky in certain directions, I have processed the data in HKL3000 and imosflm, which suggested the C2221 space group (66.59, 246.95 and 210.17). The Rmerge(0.14), completeness(94.8%), redundancy(4.6) are OK. When I tried to run Balbes with the solved native structure, the molecular replacement solution was poor. So I ran Balbes with the split domains of the native structure. Although the solutions were also poor, I found the MR score of one solution above 35. On the basis of this solution, I tried to run Buccaneer and the Rfree could be 0.46. Unfortunately, there are four molecules in the asymmetric unit and it is to hard for me to reduce the Rfree further. All best, Chenjun Tang
