[ccp4bb]: A problem about crystallization

[Li Yuanhe <yuanheli@yahoo.com>]

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Hi, colleagues:

Sorry that this question is not directly related to
CCP4. Maybe someone has the same problems as I have
and can give some suggestions:

I have a protein which crystallizes in 25%PEG4K/0.2M
Li2SO4 and pH above 8.0. The protein is in Tris-HCl
buffer and 0.2M KCL. Crystals only appear with phase
separation and they grow only up to 50 microns and
never bigger. Sometimes the phase separation in the
drop disappear with the growing of the crystals. I can
get only several single crystals in one drop but they
do not grow regardless of the drop size. Change of pH,
temperature, protein concentration, PEGs, PEG
concentration. No crystals below 0.1 M Li2SO4 or above
0.3 M Li2SO4; also no phase separation under such
conditions.  We tried the crystals (about 50 microns
in three dimension) at synchrotron. They diffract no
better than 10 angstroms.

I am trying macro-seeding and do not know if it will
work or not. Anybody can give some suggestions? Thanks
very much.

Yuanhe Li
Postdoctoral Research Associate
Department of Biochemistry and Molecular Biology
University of Illinois at Chicago




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