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
lmtho...@ou.edu
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
