Along with all the excellent suggestions so far you can also try no
cryoprotectant at all: If you harvest your crystal on a mesh loop and
remove all the mother liquor the crystal lattice itself will act as a
cryoprotectant as long as the solvent channels are smaller than 40A in
diameter (they usually are). Shameless self citation:
http://scripts.iucr.org/cgi-bin/paper?S0907444911031210
Best wishes, Matt.
On 05/05/2015 13:16, Clemens Grimm wrote:
Hi Faisal,
Did you try to simply raise the Sokalan CP7 percentage? Additives like
Glycerol can increase the solubility of proteins, in that case you
have to counteract by increasing also the precipitant concentration.
If your crystals crack, a likely reason is osmotic shock. Particularly
large crystals tend to be problematic. It is in general advisable to
transfer the cryo protectant onto the crystal within the mother
liquor rather than fishing the crystal out with a loop. In addition,
it might be necessary to prepare intermediate concentration of the
cryo protectant by mixing with reservoir solution and do a stepwise
increase. I had several projects with very large crystals that
definitely needed at least five gradual steps over a time span of more
than half an hour to extract datasets with reasonable mosaicity.
Sokalan CP7 is an acrylate copolymer. Therefore, low molecular weight
sodium polycralyte as a cryo protectant (e. g. Aldrich #420344) might
be worth a try, possibly also in combination with some amount of good
old glycerol, PEG, Trehalose, TMAO etc.
Best wishes,
Clemens
Zitat von Faisal Tarique <faisaltari...@gmail.com>:
Hello everyone
Can anybody suggest me a cryo condition for a crystal obtained in
MIDAS screen of Molecular Dimension:
G1> 0.1MTris8.0G10.1Mpotassium chloride25% v/vSOKALAN®CP7 0.1MHEPES7.0
G2>0.3Mammonium formate20% v/vSOKALAN® CP 5 0.1MHEPES7.0
Crystals are in beautiful cuboid shaped but all sorts of PEG
combinations and Glycerol formulation failed to prevent it from
cracking and dissolving.
Has anybody faced a similar situation as mentioned above and what
precaution was taken to prevent it from cracking or dissolving.
Your suggestions will be of immense help
Thanks in advance
--
Regards
Faisal
School of Life Sciences
JNU
--------------------------------------------------
Dr. Clemens Grimm
Institut für Biochemie
Biozentrum der Universität Würzburg
Am Hubland
D-97074 Würzburg
Germany
e-mail: clemens.gr...@biozentrum.uni-wuerzburg.de
phone : +49 0931 31 84031
-------------------------------------------------
--
Matthew Bowler
Synchrotron Crystallography Group
European Molecular Biology Laboratory
71 avenue des Martyrs
CS 90181 F-38042 Grenoble
France
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