Also try growing them in the presence of the cryoprotectants...
Jacob
*******************************************
Jacob Pearson Keller
Northwestern University
Medical Scientist Training Program
Dallos Laboratory
F. Searle 1-240
2240 Campus Drive
Evanston IL 60208
lab: 847.491.2438
cel: 773.608.9185
email: j-kell...@northwestern.edu
*******************************************
----- Original Message -----
From: "Natalie Zhao" <natalie.z...@stfc.ac.uk>
To: <CCP4BB@JISCMAIL.AC.UK>
Sent: Tuesday, December 15, 2009 6:20 AM
Subject: [ccp4bb] FW: [ccp4]: TDS upon flashcooling
-----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.
--
Rafael Couñago
Research Fellow
Department of Biochemistry
University of Otago
710 Cumberland St
Dunedin, New Zealand
ph: (03) 479 5148
--
Scanned by iCritical.
