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
[email protected]
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
