James and those that may be interested,
65% MPD at 4 degree C at pH 3.6 are conditions that stimulate the growth
of salt crystals, but one cannot exclude that the florets are indeed
protein.
1. If you are sure you are dealing with protein crystals try the
co-precipitant
approach: Carry out a simple screeen like 5% MPEG550 + 60% MPD ;
10% MPEG550 + 55% MPD and so on. This can be repeated with other
co-precipitants that you may have identified for other conditions you have
screened
previouysly.
2. Vary the protein concentration vs. the precipitant concentration.
The results should follow the theoretical phase diagram.
3. Use the results of Steps 1 and 2 do screen finely using seeding. Florets
often indicate a disordered initial nucleous, which can be caused by
excessive protein or
precipitant concentration, but could also be due to ther factors.
Seeding of drops that do not nucleate spontaneously will in many cases
remove
the problem.
Enrico.
On Tue, 25 Aug 2009 15:14:24 +0200, james09 pruza <james09x...@gmail.com>
wrote:
Dear all,
Sorry for the non-ccp4 question. Recently I have got some long needle of
on
35 kDa protein with 65% MPD at 4 degree C at pH 3.6 (50 mM NaOAc buffer).
The protein contains 50mM of salt. The florets are very thin. I need some
suggestions regarding the optimization of the crystallization conditions.
Thanks in advance.
James
--
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
