I would try using another processing program if you have it available, say
Mosflm. I look at similar looking diffraction data recently, though without
the salt crystals mixed in as Herman observed which you also need to take care
of in the future, and HKL did not handle if very well, Mosflm was able to
provide a usable data set. In fairness I have had the reverse occur also were
Mosflm was unhappy with the data and HKL gave usable data.
Leonard M. Thomas Ph.D.
Macromolecular Crystallography Laboratory
Oklahoma COBRE in Structural Biology
Price Family Foundation Institute of Structural Biology
Department of Chemistry and Biochemistry
University of Oklahoma
Stephenson Life Sciences Research Center
101 Stephenson Parkway
Norman, OK 73019
From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of
Sent: Wednesday, October 12, 2016 2:35:38 AM
Subject: [ccp4bb] AW: strange X-ray diffraction diagram——RNA Or Complex？
You have salt crystals in your loop, as evidenced by some very strong
reflections at high resolution. On the left, at nine o’clock, again at high
resolution, you have a collection of spots that do not seem to fit to a single
lattice. Since the low resolution region looks much cleaner, this might again
be salt or some other small molecule that formed multiple micro crystals.
However, the diffraction at low resolution looks like a bona fide
macromolecular crystal (protein and/or RNA). What I would do is to apply a
resolution cut-off and only use the low resolution data for indexing. Once you
found a good indexing, you could process the data including the high resolution
data as well.
Von: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] Im Auftrag von Liu
Gesendet: Mittwoch, 12. Oktober 2016 08:55
Betreff: [ccp4bb] strange X-ray diffraction diagram——RNA Or Complex？
Recently, I suffered a problem during my research work. I purified a zinc
finger protein, and crystallized as a beautiful cube in a reservoir solution
only containing phosphate as the precipitant, no other buffer or molecules.
However, regardless of multiple optimization, the crystal diffracted badly (7~8
Å best). I have also tried co-crystallization with dsRNA because this protein
can bind to dsRNA. Then crystals grow in a new condition（2.5M (NH4)2SO4，0.1M
BTP, pH7.0）and its form change to cluster of needle. But the X-ray diffraction
diagram is very strange（as shown in the picture）. The Data cannot be processed
with HKL2000 either. I want to figure out, could this be a RNA crystal rather
than the complex? Or is there anybody know about the crystal of RNA molecular？
Thank you very much!
Room 2071, research center in life sciences,
China Agricultural University
No. 2 yuanmingyuan west road, Haidian District, Beijing, 100193 P.R. China