The PEG could also be the problem, so you can mix your stock solutions by
the method described
below and end up with the same result as soon as you add the PEG.
See:
Frances Jurnak: Effect of chemical impurities in polyethylene glycol on
macromolecular crystallization
Journal of Crystal Growth
Volume 76, Issue 3, 2 August 1986, Pages 577-582
Enrico.
On Tue, 27 Sep 2011 18:43:09 +0200, Roger Rowlett <rrowl...@colgate.edu>
wrote:
Imidazole is basic. If you mix it directly with zinc salts you will get
zinc
hydroxide. Most screens are prepared by mixing stock solutions. In your
case
I would make up the screen from 1 M imidazole, pH 7.2, 1 M ZnSO4, and 50%
PEG-4000. Add the PEG last. This should work. You may or may not need
this
specific salt or buffer to get crystals, and could swap them out or
change
concentration as required. 50 mM buffer may not be sufficient to control
condition pH depending on the protein storage buffer composition.
Roger Rowlett
On Sep 27, 2011 11:56 AM, "Browning Christopher" <
christopher.brown...@epfl.ch> wrote:
Dear All,
My question might be a bit out of place, but perhaps someone can help.
I've screened my protein in the Nuc-Pro screen from Molecular Dimensions
and
found some crystals in condition B10. They seem to be protein crystals as
they are not highly optically active and look different to salt
crystals. So
condition B10 consist of 10% PEG 4K, 50mM Imidazole pH 7.2, 20mM Zinc
sulfate. In the screen, this condition is perfectly clear, but when I try
and make my own screen, the whole solution turns white. Apparently, Zinc
sulfate/Imidazole can be used for staining SDS-gels, but that does not
really help my a lot. Does anybody have an idea how I might be able to
keep
everything in solution, seeing that the MD guys managed somehow......
I'm a
bit desperate as I don't have many hits for this protein.
Cheers,
Chris B
--
Dr. Christopher Browning
Post-Doctor to Prof. Petr Leiman
EPFL
BSP-416
1015 Lausanne
Tel: 0041 (0) 02 16 93 04 40
--
Enrico A. Stura D.Phil. (Oxon) , Tel: 33 (0)1 69 08 4302 Office
Room 19, Bat.152, Tel: 33 (0)1 69 08 9449 Lab
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://www-dsv.cea.fr/en/institutes/institute-of-biology-and-technology-saclay-ibitec-s/unites-de-recherche/department-of-molecular-engineering-of-proteins-simopro/molecular-toxinology-and-biotechnology-laboratory-ltmb/crystallogenesis-e.-stura
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: est...@cea.fr Fax: 33 (0)1 69 08 90 71
