We routinely use a P200 to pipette drops of protein directly into a small Dewar
of liquid nitrogen. The protein forms small BB's with a volume of approximately
30 micro-L each. Pipette slowly, allowing the drops to freeze solid before
adding the next one. The frozen BB's can be picked up with forceps or a slotted
spoon and stored in a cryovial in the -80 freezer. For future experiments, you
can thaw only what you need. I have only seen one protein that couldn't recover
from this and could only be crystallized prior to freezing.
A systematic study of this procedure is described in Deng et al.
http://www.ncbi.nlm.nih.gov/pubmed/14684931
--Andrew
On 11/5/10 3:40 PM, "<Eric Karg>" <[email protected]> wrote:
Dear all,
I'm working on a protein which starts to precipitate after 3-4 days of storage
at 4 degrees or room temperature. The storage buffer contains 300 mM NaCl
because at lower salt concentrations it also tends to precipitate. Different
buffers and adding glycerol did not help although this was not done in a
systematic way. Has anyone had similar experiences? Any suggestions to overcome
this problem?
Thanks in advance!
Eric
--
Andrew M. Gulick, Ph.D.
-----------------------------------
(716) 898-8619
Hauptman-Woodward Institute
700 Ellicott St
Buffalo, NY 14203
-----------------------------------
Hauptman-Woodward Institute
Dept. of Structural Biology, SUNY at Buffalo
http://www.hwi.buffalo.edu/Faculty/Gulick/Gulick.html
http://labs.hwi.buffalo.edu/gulick
