Tjaard Pijning wrote:
I have crystals grown from 1 M sodium succinate pH 7 and have
been searching for suitable cryo conditions.
Is succinate in itself already a cryoprotectant (maybe at somewhat
higher concentration) or should I
add e.g. glycerol ? Any experience or ideas are welcome.
Thanks in advance,
*** **Ing. Tjaard Pijning*
Protein Crystallography Group
University of Groningen
Nijenborgh 4
9747 AG Groningen
The Netherlands
Tel. (31)(0)50 363 4385
Adding 25-30% glucose is sufficient to cryoprotect almost any
crystallization solution from ice formation. If your crystals can't
tolerate transfer to M.L. + glucose without cracking, you can try adding
the cryoprotectant solution gradually to the drop the crystals are in. I
usually add M.L. + cryoprotectant at 125% of the final concentration in
0.25, 0.25, 0.5, 1.0, and 2.0 drop volumes a few minutes apart to allow
for mixing and equilibration. (You can do this over the original well to
avoid excessive evaporation.)
Alternatively, you can freeze empty drops with various amounts of
glycerol and examine the frozen loops. If your solutions freeze clear,
you probably have enough glycerol to prevent ice formation.
Cheers,
--
------------------------------------------------------------------------
Roger S. Rowlett
Professor
Colgate University Presidential Scholar
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
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