I have had a fair amount of success using 2.1-2.3 M Na Malonate as a
cryo protectant for crystals from high salt conditions like yours.
Fluorinated oils are also an option, they generally are a little
easier to work with then Paratone.
Good Luck
Leonard Thomas Ph.D.
Macromolecular Crystallography Laboratory Manager
University of Oklahoma
Department of Chemistry and Biochemistry
620 Parrington Oval
Norman, OK 73019
[log in to unmask]
http://barlywine.chem.ou.edu
Office: (405)325-1126
Lab: (405)325-7571
On Oct 7, 2009, at 3:54 PM, ycheng wrote:
> Hi,
> I am trying to find an appropriate cryo-condition for my protein
> crystals.
> The mother liquid is 2-2.5M Ammonium phosphate dibasic
> 100mM TrisHCL pH8. The room-temperature diffraction looks not bad
> (mosaicity 0.8, resolution 2.6) But the diffraction turned to be very
> mosaic if I freeze the crytals in the absence of cryos or in the
> presence
> of mother liquid plus different concentration of glycerol (5%,10%,
> 15%.20%).
> I don't think the ice formation is the problem since I didn't see
> any ice
> by my eyes or ice diffraction in the presence or absence of cryos.
> Also, I
> didn't see any cracks on my crystals when I transfered them to the
> cryo
> conditions I have already tried.
> My question here is:
> 1)what's the role of cryo? I know it helps prevent ice formation.
> Based on
> my case, it looks like cryo might also help to keep the crytal
> packing good
> when frozed.
> 2) What do I need to do to find a good cryo? What in my mind is to try
> other cryos like sucrose, PEG400, ethylene glycol.
>
> Thanks a lot for your attention!
>
> Yuan
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