Dear Claudia,
These crystals dissolve in several cryoprotectant solutions and survive only
in malonic acid, with which they give diffraction at 7-8 A.
You do not mention what the room temperature diffraction is like. If you have
not tested it already, you should do so - even without malonate, you might only
get 7-8A diffraction. Assuming the room-temp diffraction is OK, you could just
try increasing the concentration of phosphate buffer - high salt can also act
as a cryoprotectant.
James
Dr. James Murray
Biochemistry Building
Department of Biological Sciences
Imperial College London
London, SW7 2AZ
Tel: +44 (0)20 7594 5276
-Original Message-
From: CCP4 bulletin board on behalf of Claudia Scotti
Sent: Fri 22/06/2007 13:42
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] How to replace 2.45M K/Na phosphate buffer - 2
Sorry: forgotten the pH: the crystals grow between pH 6.5 and 6.7.
Claudia
Claudia Scotti
Dipartimento di Medicina Sperimentale
Sezione di Patologia Generale
Universita' di Pavia
Piazza Botta, 10
27100 Pavia
Italia
Tel. 0039 0382 986335/8/1
Facs 0039 0382 303673
Date: Fri, 22 Jun 2007 14:15:47 +0200
From: [EMAIL PROTECTED]
Subject: [ccp4bb] How to replace 2.45M K/Na phosphate buffer
To: CCP4BB@JISCMAIL.AC.UK
Dear list,
I've crystals in a condition including 2,45 M K/Na phosphate buffer for the
well condition, and 1 microl protein + 0.8 microl Na/K phosphate buffer +
0.25 microl 30% 1,6-hexanediol in the drop condition.
These crystals dissolve in several cryoprotectant solutions and survive only
in malonic acid, with which they give diffraction at 7-8 A.
Among the several different possibilities, I'd like to try to optimize the
crystals, and one possiblity among others would be to change the buffer.
Any suggestions, please, about how to replace K/Na phosphate? At these
concentrations it is acting as a buffer but also as a precipitant and I was
wondering if anybody has experienced nice buffer-salt combinations that
proved to be useful starting from a similar condition.
Thanks a lot,
Claudia
Claudia Scotti
Dipartimento di Medicina Sperimentale
Sezione di Patologia Generale
Universita' di Pavia
Piazza Botta, 10
27100 Pavia
Italia
Tel. 0039 0382 986335/8/1
Facs 0039 0382 303673
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