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Dear Maria,
this is similar to the condition I used for my PhD thesis. I suppose
the following happens:
when you mix the drop the protein crystallises by inverse salting-in
because you dilute the high-salt concentration. This happens
instantaneously and you are lucky enough to observe crystals.
As you leave the drop overnight you are observing the opposite from
what normally happens: your drop gets larger instead of smaller
because the hygroscopy of the 150mM NaCl is stronger than that of 2.5%
PEG8K and you further dilute the drop so that the crystal disappears.
Check if your drops get bigger overnight to check if my assumption is
correct.
During my PhD I worked with 0.5M NaCl and maybe I am wrong that 150mM
NaCl is stronger than 2.5% PEG8k.
Best,
Tim
On 05/02/2014 01:39 PM, dusky dew wrote:
> Dear All,
>
> I am trying to crystallize a protein with Adenosine. My protein is
> in 20 mM Tris, 300 mM NaCl and the crystals appear in a condition
> with 5 percent PEG8K, 0.1 M Sodium Cacodylate. The protein is
> incubated with adenosine for 1/2 hr before setting the drop. The
> crystals appear right after the drop is set but unfortunately they
> dissolve overnight. The plate is kept at 16 degree.
>
> Could anyone elaborate on this. Is it possibly occurring because
> Adenosine has stability issues.
>
> Thanks for your suggestions. ~ Maria
>
- --
- --
Dr Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
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