Dear Brenda, I'd suggest using a mixture of 75% Paratone-N oil with 25% light, white mineral oil. Mix the two thoroughly with a positive displacement pipette then add a small amount next to the mother liquor (ML) drop. Remove a crystal from the ML using a matched cryo loop (the smaller the better) and then dip it completely into the oil. Gently slide the side of the loop containing the crystal against the surface beside the ML to wick off some of the oil, which will also remove some of the aqueous layer on the crystal surface. Then dip the crystal back into the oil; it usually takes 2-3 times to completely remove the aqueous layer. This works about 80% of the time for me for crystals grown from high salt conditions. Method courtesy of A. McPherson and J. Pflugrath.
HTH, Jeff -----Original Message----- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Schulman, Brenda Sent: Wednesday, August 19, 2009 12:19 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Cryoprotection in > 3M ammonium sulfate Hello! I would be grateful for suggestions on cryoprotectants for crystals growing in > 3M ammonium sulfate. Thanks! Brenda Email Disclaimer: www.stjude.org/emaildisclaimer
