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 DTTCrystallization 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
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