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
