Re: [ccp4bb] Freezing under oil

[Sabine Schneider]

Hello Claudia,

Under what conditions did the crystals grow? If its sodium acetate and 
ammonium sulphate I would try adding sodium malonate as a cryo 
protectant (with 2-2.3M ammonium sulphate adding 0.6-0.8M Na malonate 
should be sufficient) or increasing the ammonium sulphate concentration.

Sabine



Claudia Scotti wrote:
 
Dear list,
 
I'm trying to freeze crystals in cryoconditions containing the following:
 
0.1 M Sodium acetate pH 4.4
2.15-2.3 M Ammonium sulphate
7% n-butanol
15% glycerol
 
The problem is that the crystals (beautiful hexagonal prisms) seem to 
shatter in a random fashion: some are unaffected, some, coming from 
the same drop, disgregate miserably. One even split into three parts, 
of which two disgregated and one survived perfectly well.
 
I've tried both by moving the crystals directly in the cryocondition 
and by progressively increasing the glycerol concentration to no avail.
 
Shall I just select those that survive?
 
I was wondering if anybody has ever had this same problem and 
if freezing under oil could be an alternative. If yes: any suggestions 
on how to fish the crystals? I tried it in the past, but I found it 
very difficult...
 
Experiences and suggestions are welcome.
 
Claudia
 
 
 


Claudia Scotti Dipartimento di Medicina Sperimentale Sezione di 
Patologia Generale Universita' di Pavia Piazza Botta, 10 27100 Pavia 
Italia Tel. 0039 0382 986335/8/1 Facs 0039 0382 303673



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Dr. Sabine Schneider
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