You could try conditioning your crystals in a dehydration device (such
as the FMS (proteros) or the HC1 (EMBL)). Even if you crystals don't
improve from dehydration they can often be cryocooled without any
cryoprotectant after the mother liquor has been removed. We offer the
HC1b at the ESRF to users on 14-1 or 14-2, cheers, Matt.
Natalie Zhao wrote:
-----Original Message-----
From: owner-c...@dl.ac.uk [mailto:owner-c...@dl.ac.uk] On Behalf Of Rafael
Couñago
Sent: 14 December 2009 20:22
To: c...@ccp4.ac.uk
Subject: [ccp4]: TDS upon flashcooling
Dear all,
I got these beautiful looking crystals that grow in high salt (1.8M) and
diffract under 2.0A at room temp. My attempts so far to cryo protect
them have resulted in a loss of resolution (2.5A tops) and increased
anisotropy.
I have tried some of the usual suspects; no cryo, ethylene glycol,
glycerol (even 5% makes my crystal crack), sucrose, glucose, paratone-n
(no diffraction at all). I have tried both dipping the crystal straight
into liquid nitrogen and flash cooling it in the cryostream.
An interesting observation is that the diffraction pattern following
freezing has a substantial amount of thermal diffuse scattering (but no
ice rings). If I remove the crystal from the cryostream and re-anneal
it at room temp (in air or in mother liquor or mother liquor + cryo)
most of the TDS goes away, but the max resolution is still around 2.5A
and the higher anisotropy is still there. Extending re-annealing times
lead to cracking of the crystal.
My two questions would be:
- any thoughts on cryo solutions?
- does the result from the re-annealing experiment ring any bells?
Would this be an indication that I need the cooling to be faster or slower?
Cheers,
Rafael.
--
Matthew Bowler
Structural Biology Group
European Synchrotron Radiation Facility
B.P. 220, 6 rue Jules Horowitz
F-38043 GRENOBLE CEDEX
FRANCE
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Tel: +33 (0) 4.76.88.29.28
Fax: +33 (0) 4.76.88.29.04
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