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Hi Dirk,
As we know, the buffer conditions in which the protein is stored can
have a significant influence as well and then interpretation of pI is
all relative and all awry. I try to get the protein all happy and
soluble while purifying it. Then, sometimes the protein is so happy that
it will refuse to precipitate out of solution during crystallization
attempts. Huh!
Have you tried the ZetaSolÔ screen from Molecular Dimensions? I recently
used it. It tests crystallisability based on the net charge of the
protein, of the precipitant/salt, pH etc.
Here's a link, if you didn't know:
http://www.nagase.co.jp/shiyaku/Md_files/ZetaSol.htm
Hope that helps.
Raji
Bussiere, Dirksen wrote:
All:
The last question on expression of a highly basic protein brought
up a question I wanted to post. We are working with a highly
positively charged protein (numerous Lys and Arg residues on the
surface) and are having no trouble expressing it, but are having
trouble crystallizing it. We see some small crystals that appear to
be protein crystals from a high-pH condition (as you would expect for
a basic protein), but are having trouble optimizing the conditions. I
was wondering: has anyone worked out a crystallization screen (or
mini-screen) for highly basic proteins? If so, can someone provide me
with a reference ? Thanks.
-Dirk
Dirksen Bussiere, Ph.D.
Associate Director
Computational Chemistry and Structural Chemistry
Chiron Corporation
4560 Horton Street, M/S 4.4
Emeryville, CA. 94608
Phone: 510-923-2114
Fax: 510-923-5550
e-mail: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
