Hi Yuri,
I've had a very similar experience last week which ended badly. I opted to cryo my new crystals using my favourite cryo. Diffraction showed at least the crystals were protein but not much more. A classic example of cryo killing crystals. I mounted the remaining tiny fragment from the drop in a room temperature mount and got 15 images before it died. From this I got a cell and lattice even though it only diffracted to 6Ang. If had mounted a larger piece of crystal first off I might of been able to get a dataset with much shorter exposures. I would encourage either an in-situ test you have the equipment or use a capillary in whichever way suits. There are methods that allow recovery of the crystal after the test. At least this way you can (a) feel satisfied when you crush it up afterwards for seed because it didn't diffract at all or (b) successfully cryo your nicely diffracting crystal.
Good Luck!
David Hargreaves
Associate Principal Scientist
_____________________________________________________________________
AstraZeneca
DECS, CP&SS
Mereside, 50F49, Alderley Park, Cheshire, SK10 4TF
Tel +44 (0)01625 518521 Fax +44 (0) 1625 232693
David.Hargreaves @astrazeneca.com
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-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Yuri Pompeu
Sent: 01 December 2012 01:23
To: [log in to unmask]
Subject: [ccp4bb] To cryo or not to cryo...
Dear community,
I have what seems to be a pretty decent single crystal that grew from a screen set up 2 weeks ago.
I am trying to reproduce it but so far I have not succeeded. I am however afraid the crystal that did form will start to deteriorate. So this brings me to dilemma, I feel like I should try and mount this crystal and shoot it. But since I only have 1 sample, I do not want to mess this up... I am inclined to try cryo conditions, but I am afraid the addition of a cryo such as glycerol could destroy the little guy.
The crystal formed in 30% PEG 4000, 0.1M NaCitrate pH5.6 and 0.2M NH4AcO, I wonder if this is a cryo condition already?
Any suggestions would be appreciated.
best,
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