One thing that I have had work in the past is just increase the
percentage of PEG. I think something around 30-35% may work for
PEG4K, maybe a little higher. Most PEGS will work as a cryo
protectant if the concentration is high enough.
Also as mentioned before you could try stepping up the glycerol
concentration very gradually. I had a colleague who said the protein
he worked on in grad school had to be stepped up 1% increments or it
would crack and fall apart. IIRC he had better then 2.0 ang. data for
the final structure.
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 Sep 1, 2009, at 5:25 AM, Fengxia Liu wrote:
Dear All,
Could you please help me solve this problem?
I have a sensitive crystal, the mother liquor is 10% PEG4k+ 100 mM
Tris-buffer pH 8.5, crystal is big and good but very sensitive, when
i put it in cryoprotectants, cracking happened. First i used
artificial mother liquor + 25% v/v glycerol, slowly decrease to +
12.5% v/v glycerol, all crystals cracked after immersed, finally i
tried 50% mineral oil + 50% paratone, it still cracked (4- 5 cracks,
but not broken) . even this cracked crystal can give me 3.2 angstrom
diffraction, so no cracked crystal might give me 2.0+ angstrom
diffraction. Now i don't have many crystals to try so many
cryoprotectants, so anybody has experience on this? any suggestion
would be greatly appreciated.
Thank you.
Fengxiale
