Hi Mike,
I would suggest that you run the protein sequence through the JCSG XtalPred
server: http://ffas.burnham.org/XtalPred-cgi/xtal.pl (Bioinformatics.
<javascript:AL_get(this, 'jour', 'Bioinformatics.');> 2007 Dec
15;23(24):3403-5. XtalPred: a web server for prediction of protein
crystallizability).
This will give you a good idea if it is likely to crystallize or not
(assuming that is what you are trying to do since you posted here....) if you
need to purify and stabilize the protein at high pH.
As a test case, I tried with a protein seq of predicted pI of 10.69
(Holliday junction resolvase YqgF) to generate a graph comparing this with the
distribution of crystallization probabilities from TargetDB
(http://ffas.burnham.org/XtalPred-cgi/result.pl?dir=webdb/1215642963.15786/0).
The second graph shows the pI and observed success/observed failures in the pI
ranges of 8-9 and 9-11. Failures are much higher than successes in when pI > 9.
Nevertheless, many DNA binding proteins have high pI and there are many
structures of those in unliganded form and in complex with DNA, etc.
So, if already have the protein expressed and stabilized/purified at pH
10.2, it is defnitely worth setting up crystallization screens...........while
also trying to explore binding partners or construct modifications and other
things.
Hope this is helpful.
Regards,
Debanu.
________________________________
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Michael
Colaneri
Sent: Wednesday, July 09, 2008 3:26 PM
To: [email protected]
Subject: [ccp4bb] high pI protein
Hi all,
We have a protein with high pI and we can only dissolve it at pH 10.2. Is this
a reasonable pH to work with? Should we try to bind something to it to
decrease the pH we are working with? We would appreciate all suggestions.
Mike Colaneri
