You can also set your cryostream to something like 253K... or even lower
with high salt. Better than RT and still no freezing. You need to use
one of these new loop covers to prevent drying out.
Flip
mjvanraaij wrote:
> 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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