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
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-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of
Todd Geders
Sent: Monday, March 15, 2010 8:18 AM
To: [log in to unmask]
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
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