why not stay with room temp?
many structures have been solved at RT...
Mark J. van Raaij
Dpto de Bioquimica, Facultad de Farmacia
Universidad de Santiago
15782 Santiago de Compostela
Spain
http://web.usc.es/~vanraaij/
researcherID: B-3678-2009
On 15 Dec 2009, at 13:20, Natalie Zhao wrote:
> -----Original Message-----
> From: [log in to unmask] [mailto:[log in to unmask]] On Behalf Of
> Rafael Couņago
> Sent: 14 December 2009 20:22
> To: [log in to unmask]
> 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 Couņago
> Research Fellow
> Department of Biochemistry
> University of Otago
>
> 710 Cumberland St
> Dunedin, New Zealand
> ph: (03) 479 5148
>
> --
> Scanned by iCritical.
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