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: [email protected] 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: [email protected] > > 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 > _________________________________________________________________ > Make every IM count. Download Windows Live Messenger and join the i'm > Initiative now. It's free. > http://im.live.com/messenger/im/home/?source=TAGWL_June07 _________________________________________________________________ Make every IM count. Download Windows Live Messenger and join the i'm Initiative now. It's free. http://im.live.com/messenger/im/home/?source=TAGWL_June07
