Enrico Stura
Fri, 05 Feb 2010 04:43:36 -0800
On Fri, 05 Feb 2010 05:39:14 +0100, rui <ruis...@gmail.com> wrote:
Hi, All, We are trying to crystallize a protein and found some initial hit in the following conditions, pH 4.8, 0.2 M AS or some other salts ( NaCl,LiCl, MgCl2 ), 32% PEG4000 orPEG3350 ). However the quality of the crystal is not so great,some of themlook like needle cluster(very long in length), some of them look like multi-crystals or hollow inside.
Such growth problems are likely due to the quality of the protein solution. Changes in precipitant concentrations are likely to be ineffective. Try ion exchange purification.
We tried to optimize the pH and PEG and tested one that diffracts at 2.9A. For the next, how to improveresolution?Any suggestions? Even mutate the protein to get a high resolutionis ok, generally what kind of mutation would make proteins crystallize better? Thanks.
It is not mutations that will improve diffraction, it is small changes in crystal contacts. The Discussion section from: http://pubs.acs.org/cgi-bin/article.cgi/cgdefu/2007/7/i11/html/cg700698d.html may help. Enrico -- Enrico A. Stura D.Phil. (Oxon) , Tel: 33 (0)1 69 08 4302 Office Room 19, Bat.152, Tel: 33 (0)1 69 08 9449 Lab LTMB, SIMOPRO, IBiTec-S, CEA Saclay, 91191 Gif-sur-Yvette Cedex FRANCE http://www-dsv.cea.fr/en/ibitecs/82 http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html e-mail: est...@cea.fr Fax: 33 (0)1 69 08 90 71