Hi, In addition to the other insightful reply, I'd like to remind folks that glycerol solutions (neat glycerol also does it but slower) can undergo degradation resulting in various mono- and di-carboxylic acids, some of which are decent chelators.
Artem --- When the Weasel comes to give New Year's greetings to the Chickens no good intentions are in his mind. -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Ho-Leung Ng Sent: Wednesday, May 13, 2009 2:20 PM To: [email protected] Subject: [ccp4bb] Glycerol as metal chelator? I am working with a metalloprotein that binds cobalt and iron. I was surprised that the solved structures showed the crystals cryoprotected with glycerol are metal free while crystals cryoprotected with ethylene glycol had the metals present. Both cryoprotectant solutions contained metal in the 10 mM range and are buffered at pH 9. I assume glycerol must be a weak chelator otherwise it wouldn't be so ubiquitous in protein biochemistry. Has anyone else experienced this before with glycerol? Ho UC Berkeley
