Hi Rashmi, The concentration of your stock solution will depend on how you plan to mix your screen conditions. It's not really that important as long as: 1.) Glutathione stays soluble, and 2.) You can make your condition with the desired glutathione concentration. If your glutathione is reduced you should probably make the stock fresh each time because reduced glutathione will oxidize, but if it is already oxidized it is probably ok to keep a stock for a little while. I would maybe keep it at 4 degrees...I'm not sure how well glutathione tolerates the freezer. If you need to make stock solutions that you plan to keep around for a while, remember that oxidative formation of disulfides is pH-dependent, with lower pH favoring the thiols (reduced) and higher pH favoring the disulfide (oxidized). This is because the thiol must be deprotonated before oxidation. If you're making a stock of reduced glutathione, I would recommend a pH of 6.5. For oxidized glutathione, I would recommend around 8.
Hope this helps, Mike ----- Original Message ----- From: "rashmi panigrahi" <rashmi.panigrah...@gmail.com> To: CCP4BB@JISCMAIL.AC.UK Sent: Tuesday, February 22, 2011 11:42:15 PM GMT -08:00 US/Canada Pacific Subject: [ccp4bb] stock solution of glutathione Hi, I wanted to use glutathione for cocrystallizing with my protein at about 5mM concentration. What is the concentration of the stock solution to be prepared for crystallization studies. Do I have to make the stock solution of glutathione fresh each time or can I make the stock and store at -20degrees? Should I prefer to make the stock solution at a particular pH to prevent its oxidation?? suggestions awaited....... -- rashmi -- Michael C. Thompson Graduate Student Biochemistry & Molecular Biology Division Department of Chemistry & Biochemistry University of California, Los Angeles mi...@chem.ucla.edu
