Ji,
probably the oil doesn't work and the glycerol gets you into problems
with phase separation in 2.5 M AmS
I recommend sucrose or other sugars with AmS - 20-22% (w/vol) should
do and you get no phase separation
At the same time you may need to increase the AmS considerably - often
the protein solubility in AmS increases significantly in the presence
of cosolvents.
I have previously had success with crystals grown in 1.9 M AmS, that
were cryoprotected by gradual transfer to 2.6 M AmS/20% sucrose. The
drops were then equilibrated against 3.5M AmS for a couple of hours
(dehydration) - without the final step in place (dehydration) the
crystal diffraction would be anisotropic at 3.5 Å resolution rather
than isotropic at 2.7 Å which was also the full potential revealed
from capillary-mounted crystals.
Poul
On 24/06/2008, at 02.14, Ji lee wrote:
> Dear,
>
> I have a crystal diffracted anisotrophically. I tested with a few
> different cryo conditions like oil, glycerol in different
> concentration to get a better data but these conditions didn't help
> any.
> Using capillary method improved the diffraction (isotrophic) but the
> crystal couldn't survive during the data collection.
> Is there any methods or cryo conditions I can use to improve my
> diffraction data?
> This crystal grew in 2.5M Ammonium Sulfate.
>
> Thank you so much.
>
> Ji
>
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