Hi,
I had this exact problem before. The method below worked for me: Take a sturdy needle (like one of the microneedles from a Hampton kit or a very thin syringe needle) and (while observing the whole thing under a scope) stick the needle into the plastic a bit away from the crystal. Push hard. If you're using polarizers, you may b abe to visualize the stress forces in the plastic by the shifting of the colors. The basic idea here is to stress the plastic under the crystal w/o touching the crystal in any way. In my case the bloody things just popped off. Sometimes you have to push quite hard, and to wiggle the needle a bit - and beware, they can slip and ruin your drop. But this really worked quite well! Artem _____ From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Savvas Savvides Sent: Tuesday, January 27, 2009 6:06 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] sticky crystals Dear colleagues, we have been growing crystals of a protein complex in sitting-drop geometry that stick to the bottom of the drop remarkably well. It's as if they are glued onto the plastic. This makes crystal handling next to impossible without destroying the crystals. We have tried whiskers, loops, all kinds of micro-tools, and pipetting techniques to no avail. I can say at the outset that we have been unsuccessful in growing these crystals in hanging-drops or at 4 degrees. Deglycosylating the complex also leads to nowhere. In fact, we are only able to get crystals from homogeneously glycosylated protein produced in HEK293S/I- cells. In the meantime we are playing with the idea of siliconizing the sitting-drop depressions to alter the crystal/plate interface. But then again, nucleation events on the plastic may be the reason we are getting crystals in the first place. We have also thought of trying microseeding to have more control on nucleation issues. Our protein production is quite limiting and forces us to be very selective with our experimentation. Nonetheless, while we are waiting for fresh material to explore some of these ideas we would like to make the most out of the crystals we have grown thus far. We would therefore very much appreciate any input/ideas on manipulating these crystals for data collection. Best wishes Savvas ---- Savvas Savvides L-ProBE, Unit for Structural Biology Ghent University K.L. Ledeganckstraat 35 9000 Ghent, BELGIUM office: +32-(0)9-264.51.24 ; mobile: +32-(0)472-92.85.19 Email: savvas.savvi...@ugent.be http://www.lprobe.ugent.be/xray.html From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Katarina Moravcevic Sent: Tuesday, January 27, 2009 10:52 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] pseudo translation Hi all, here is a question from a beginner. I have a home source data set that indexed and scaled in a P2 space group (a=46.704,b=59.362, c=48.783, alpha=90.0, beta=104.469, gamma=90.0) with predicted 2mol/au. After failing to get a MR solution with Phaser I ran the phenix.xtriage which showed that I have a large (89.18) Patterson peak at 0.5 0 0.5 which indicates pseudo translational symmetry. I was wondering if there is anything I could do with this data to get around this problem. Given that I don't have a lot of experience any suggestion/explanation would be fantastic. Thanks in advance K E-mail message checked by Spyware Doctor (6.0.0.386) Database version: 5.11630 http://www.pctools.com/spyware-doctor-antivirus/ <http://www.pctools.com/en/spyware-doctor-antivirus/>
