Dear Tang,
I noticed that your diffraction images seem to have been recorded
on a 3x3 CCD detector. With this type of detector, fine slicing is
often discouraged (because of the readout noise), and yet with the two
long cell axes you have, any form of thick (or only semi-fine) slicing
would result in spot overlaps.
What, then, was your image width? Would you have access to a
beamline with a Pilatus detector so that you could collect fine-sliced
data?
I would tend to agree with Herman that your crystals might be
cursed with lattice translocation disorder (LTD), but you might as
well try and put every chance of surviving this on your side by making
sure that you collect fine-sliced data. LTD plus thick slicing would
give you random data along the streaky direction. Use an image width
of at most 0.1 degree (0.05 would be better) on a Pilatus, and use XDS
to process your images.
Good luck!
Gerard
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On Thu, Jul 13, 2017 at 01:21:02PM +0100, Tang Chenjun wrote:
> 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
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