Hi Todd, There are many compounds that have color centers which change color as soon as they are exposed to X-rays. Some turn, blue, some pink, some yellow etc. I'm not sure which one is the chameleon in your buffer but you can bring them separately next time and we can shoot them one by one. Cheers, Nukri
Ruslan Sanishvili (Nukri), Ph.D. GM/CA-CAT Biosciences Division, ANL 9700 S. Cass Ave. Argonne, IL 60439 Tel: (630)252-0665 Fax: (630)252-0667 [email protected] -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Todd Geders Sent: Monday, March 15, 2010 8:18 AM To: [email protected] Subject: [ccp4bb] Blue color upon X-ray exposure? Greetings, On a recent synchrotron trip, certain frozen samples were turning a blue upon exposure to the beam. Attached is a representative image from the crystal-centering camera. If you take snapshots down the crystal, you can make blue dots. Note that it also colors the frozen solution in addition to the crystal. Details on conditions: 20 micron beam, unattenuated beam, 12.000 keV, GM/CA at APS Protein solution: 20mM HEPES-KOH pH 7.5, 100mM KCl, 0.1mM EDTA, 2mM DTT Crystallization solution: 39% w/v PEG 6000, 0.1M HEPES-KOH pH 7.6, 0.2M Ammonium sulfate Cryo protection: Added 7% v/v glycerol as cryoprotectant Anyone have any ideas on what is causing the color change? Todd Geders University of Minnesota Dept. of Medicinal Chemistry 308 Harvard St. SE, #8-101WDH Minneapolis, MN 55455 Office 2-163 WDH / Lab 2-160 WDH Phone: 612-624-2448
