You can sometimes cryoprotect crystals like this with the Mitegen low viscosity cryo oil and their micro mount loops. If that doesn't work, then you can gradually raise the concentration of sucrose or ethylene glycol so that your crystals freeze well. I don't think it should take anything like 25% sucrose to cryoprotect this in a small mount with little loose solvent around the crystal. Probably less than 10% would do the trick if you can really wick away most of the liquid and get it into the liquid nitrogen as rapidly as possible. Robert Thorne's lab at Cornell has been important in exploring this cryoprotection space.
(from the lab web page) Effects of cryoprotectant concentration and cooling rate on vitrification of aqueous solutions. V. Berejnov, N. S. Husseini, O. A., Alsaied and R . E. Thorne, J. Appl. Cryst. 39, 244-251 (2006). Hyperquenching for Protein Crystallography. M. Warkentin, V. Berejnov, and R. E. Thorne, J. Appl. Cryst. J. Appl. Cryst. 39, 805-811 (2006). Cryocrystallography in capillaries: critical glycerol concentrations and cooling rates. M. Warkentin, V. Stanislavskaia, K. Hammes and R. E. Thorne, J. Appl. Cryst. 41, 791-797 (2008). On Jul 10, 2012, at 11:50 AM, Christian Roth wrote: > Hi, > > I have used pure malonate (above 3M) for a similar condition. Sometimes the > cryoprotectant alone, without reservoir works quite well > > Cheers > > Christian > > Am Dienstag 10 Juli 2012 18:28:30 schrieb m zhang: >> regaentDear All, >> I am sure this question was discussed before. But I am wondering if anyone >> got the same experience as I do. I got a crystal out of condition with 1M >> KCl, 1.4M Ammonium sulfate at pH7. I tried to use glycerol, ethylene >> glycol, 25% sucrose, paraton-N oil, or ammonium sulfate itself: The >> problem is that all the cryo plus original reagents in the reservoir >> precipitate the salts out. And more serious problem is because of high >> salt in the condition, while I am trying to loop the crystal, both the >> drop and cryoprotectant drop form salt crystals (not sure it is KCl or >> ammonia sulfate) significantly and very quickly, that cause my crystal >> dissolved. My crystal doesn't seem to survive paraton-N oil. Does anyone >> here have similiar case? any suggestion will be appreciated. Thanks,Min >>
