Dear Pascal,
We have the case of a protein that gelifies without precipitating when
bearking overexpressing E. coli cells. We had a look at the sample in
electron microscopy and the protein polymerises and forms "irreversible
and very pretty" fibers (explaining the gel). Maybe you want to have a
look at your sample to see what kind of structure it forms.
Cécile
Le 23/04/13 00:36, Pascal Egea a écrit :
Dear All,
I am presently faced with a peculiar case in the lab. We are
expressing a protein in E. coli and we are able to express it as a
fusion protein without problems . Fusion cleavage goes well and the
final product looks homogenous by size-exclusion chromatography with
the expected molecular weight. There are no signs of aggregation.
However when we lower the salt concentration by dialysis then the
protein forms a gel. transparent , optically clear, with no fluffy
material (in the cold room).
Gelification seems to occur when we lower the concentration below 100
mM NaCl. This protein has a fairly high pI (~9.0). Attempts to reverse
the process by gentle heating or salt addition have been so far
unsuccessful. It is not a thermophilic protein. We have not been able
to obtain crystals so far.
Has anyone already observed this kind of behavior and/or have any
suggestions?
Many thanks in advance .
--
Pascal F. Egea, PhD
Assistant Professor
UCLA, David Geffen School of Medicine
Department of Biological Chemistry
Boyer Hall room 356
611 Charles E Young Drive East
Los Angeles CA 90095
office (310)-983-3515 <tel:%28310%29-983-3515>
lab (310)-983-3516 <tel:%28310%29-983-3516>
email [email protected] <mailto:[email protected]>
--
Cécile Breyton
Institut de Biologie Structurale
UMR 5075 CNRS/CEA/UJF
41, rue Jules Horowitz
38027 Grenoble cedex 1 France
---
Tel: +33 (0)4 38 78 30 37
Fax: +33 (0)4 38 78 54 94
Courriel : [email protected]
http://www.ibs.fr/groups/membrane-and-pathogens-group/ssimpa/article/ssimpas-1109
