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I do not know the answer to your question but yet have a suggestion: you
can try to crystallise your protein by (inverse) salting-in. Having a
reservoir with lower vapour pressure (e.g. by lower salt concentration)
should make your drop take up water, i.e. let the salt concentration go
down.
According to your description the protein seems to precipitate under these
conditions, and if you find the right additive it might do so in
crystalline form.
I remember such a case where we only needed (initially) 4% PEG 6k, no salt
and some buffer to stabilise the pH. The protein was in 500mM NaCl and
crystallised after about 5 days (and in one out of a few thousand
conditions such a crystal would be C2 instead of P65 and diffract to 1.6A
instead of 3.5A ;-) )
Cheers, Tim
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
On Thu, 9 Nov 2006, Stefano Benini wrote:
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Dear All,
I am trying to crystallise a protein that requires 1M NaCl in order to be
happy in solution of about 15 mg/ml (actually with 1M NaCl I can go much
higher than this).
This is influencing my crystallisation trials just because NaCl is highly
hygroscopic
does any of you know which salt (possibly not higher than of 100-200mM) or
wathever I could try to eliminate NaCl and the above mentioned problem?
thank you very much
best regards
Stefano
--
**********************************
Stefano Benini Ph.D.
http://www.ysbl.york.ac.uk/~benini
York Structural Biology Laboratory
University of York
Heslington York YO10 5YW United Kingdom
Tel.:+44 1904 328276
Fax: +44 1904 328266
"verba volant scripta manent"
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