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* Fill the liquid propane into vials. For short time storage and crystal handling put the vials in a flat liquid nitrogen bath. If propane becomes solid after a while just remove the vial from the liquid nitrogen and put it on the desk; let it stand for a while until it is liquid again and put it pack into the nitrogen bath. | * Fill the liquid propane into vials. For short time storage and crystal handling put the vials in a flat liquid nitrogen bath. If propane becomes solid after a while just remove the vial from the liquid nitrogen and put it on the desk; let it stand for a while until it is liquid again and put it pack into the nitrogen bath. | ||
* Plunge the crystals just into the vials and wait until the propane is solid. | * Plunge the crystals just into the vials and wait until the propane is solid. | ||
== Salts as precipitants ... == | |||
Some salts may also serve as cryoprotectants: malonate (see Acta Cryst D59, 2356), formate, ammonium sulfate (at >3.5 M), lithium sulfate, and perhaps others. Anything with a flat solubility vs temperature is a good candidate. Mixing of different cryos can often have a superior protective effect to single-component cryos of the same total concentration (the "confusion principle"), so there are a lot of combinations to try. | |||
== See also == | |||
* Cryoprotectant database used to be at http://idb.exst.jaxa.jp/db_data/protein/search-e.php? or http://idb.exst.jaxa.jp/db_data/protein/200304E02478000.html ; still to be found at http://web.archive.org/web/20111011202903/http://idb.exst.jaxa.jp/db_data/protein/search-e.php | |||
* see concentrations given in: McFerrin and Snell, J.Appl.Cryst (2002) 35, 538 and Mitchell and Garman, J.Appl.Cryst. (1996) 29, 584 | |||
* faster freezing: a simple means (blowing away the gas layer) is described by Warkentin et al. (2006). J. Appl. Crystallogr. 39, 805. | |||
* annealing: e.g. Harp, J., Timm, D. & Bunick, G. (1998) Macromolecular crystal annealing: overcoming increased mosaicity associated with cryocrystallography. Acta Cryst. D54, 622-8; Yeh, J. & Hol, W. (1998) A flash-annealing technique to improve diffraction limits and lower mosaicity in crystals of glycerol kinase. Acta Cryst. D54, 479-80; Kriminski, S., Caylor, C.; Nonato, M., Finkelstein, K. & Thorne, R. (2002) Flash-cooling and annealing of protein crystals. Acta Cryst. D58, 459-71 | |||
* slow cooling: Warkentin, M. & Thorne, R. E. (2009) Slow cooling of protein crystals. J Appl Cryst. 42, 944-952 | |||
* This cryocrystallography webinar lists some common cryoprotectants: http://www.rigaku.com/protein/webinar-001.html | |||