Dear Theresa Cryo-cooling the crystals straight out of their drops or after brief incubations in crystal stabilization solutions containing >2M ammonium sulfate may be the way to go. Here is a copy/paste piece from Kyndt et al (2007) Biochemistry 46, 95-105. All the best Savvas
Aliquots (0.5 í L) of the seed suspension (diluted 1:100 in stabilization buffer) were introduced into a series of fresh hanging drops (containing 4 í L of protein sample and 4 í L of reservoir solution) that had been equilibrated for 24 h over reservoirs containing 3 M ammonium sulfate and 20 mM sodium phosphate, pH 5.4- 6.2. Single crystals with bipyramidal morphology grew after 1 week to a final size of 0.150 mm 0.150 mm 0.100 mm. To prepare crystals for data collection under cryogenic conditions (100 K), crystals were flash-cooled by plunging them directly from their native drops into liquid nitrogen. A series of cryocooling conditions using a variety of cryoprotecting reagents such as glycerol, sucrose, PEG 400, and paratone indicated that only crystals flash-cooled by plunging them directly from their native drops into liquid nitrogen produced diffraction of acceptable quality. On 05 Feb 2012, at 23:49, Theresa H. Hsu wrote: > Hi all > > Is there a list of conditions to be tried *first* for cryoprotectant? My > crystals diffract at room temperature capillary but no in 30% PEG 400. > Crystals are from 2 M ammonium sulfate. > > Thank you. > > Theresa
