Ursula,
Most compounds used for cryosolutions glycerol, ethylene glycol, propane
diol increase protein solubility.
A warning, these compounds are also hygroscopic, you need to change your
vapour diffusion methodology.
Vera L., Czarny B., Georgiadis D., Dive V., Stura E.A. (2011) Practical
Use of Glycerol in Protein Crystallization. Cryst. Growth & Des. 11:
2755–2762.
http://pubs.acs.org/doi/abs/10.1021/cg101364m
The lack of success in crystallizing proteins in glycerol are due to the
reasons decribed in the paper.
Enrico.
On Fri, 20 Feb 2015 00:33:48 +0100, Ursula Schulze-Gahmen
<uschulze-gah...@lbl.gov> wrote:
Hi Enrico,
How are you? I see you are now in France.
I have also a question about protein complex solubility. I have a
multi-protein complex that also binds RNA. This Protein-RNA complex can
be
concentrated to 5- 10 mg/ml, but starts precipitating after storage at 4
degrees for several hours ( and can often be resolubilized at room
temperature). The current buffer is 20 mM HEPES 7.3, 0.2 M NaCl, 0.05 M
KCl, 3 mM MgCl2, TCEP. I don't want to increase salt concentration. What
are your suggestions to try to improve the solubility?
Best
Ursula
On Tue, Feb 17, 2015 at 2:00 AM, Enrico Stura <est...@cea.fr> wrote:
Francesca,
The most common failure is to have an excessive amount of salt (salting
in/ salting out), glycerol or other solubilizing
ingredient in your protein solution. I would suggest that you change the
pH and reduce the salt in your protein solution,
by microdialysis if you do not have much protein, and screen again.
If share with ccp4bb the exact formulation of your protein solution you
might get more suggestions.
Enrico.
On Tue, 17 Feb 2015 05:23:05 +0100, Mattiroli,Francesca <
francesca.mattir...@colostate.edu> wrote:
Hi all,
I am struggling with a protein complex that is too soluble. I have
reached about 20 mg/ml but I still observe very little precipitation
(clear
drops in 90-95% of the tested conditions). The proteins are expressed
in
insect cells and going to higher concentration is not easily
achievable.
I have tried different buffer conditions (salt concentration and pH)
and
I am testing temperatures. I am at a loss with what to try next.
Do you think PTMs (phosphorylation, acetylation) might be causing this?
Any input on how to decrease solubility?
Thank you very much in advance,
Francesca
--
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
http://www-dsv.cea.fr/ibitecs/simopro/ltmb/cristallogenese
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://scholar.google.com/citations?hl=en&user=Kvm06WIoPAsC&pagesize=100&;
sortby=pubdate
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: est...@cea.fr Fax: 33 (0)1 69 08 90
71
--
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
http://www-dsv.cea.fr/ibitecs/simopro/ltmb/cristallogenese
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://scholar.google.com/citations?hl=en&user=Kvm06WIoPAsC&pagesize=100&sortby=pubdate
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: est...@cea.fr Fax: 33 (0)1 69 08 90 71
