International
Tables for Crystallography Volume C Mathematical, physical and chemical tables Edited by E. Prince © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. C. ch. 3.4, p. 167
|
Several airstream devices have been described to cool protein crystals to around 250 K [Marsh & Petsko (1973), temperature range 253 to 303 K; Rossi (1989
), temperature range 242 to 335 K; Machin, Begg & Isaacs (1984
), 258 to 293 K; Fischer, Moras & Thierry (1985
), temperature range 263 to 293 K; Fraase Storm & Tuinstra (1986
), 250 to 350 K; Arndt & Stubbings (1987
), 248 to 353 K]. The devices of Machin, Begg & Isaacs, Fraase Storm & Tuinstra and Arndt & Stubbings involve thermoelectric modules utilizing the Peltier effect. The space available to accommodate the sample is usually very limited and care has to be taken with the length of the capillary and other aspects of crystal mounting. Hovmöller (1981
) has designed an extension to the cooling delivery tube that minimizes air turbulence at the sample. Various devices have been described that operate down to near liquid-nitrogen temperature and that can be fitted to a variety of data-collection systems. These include the rotation camera (Bartunik & Schubert, 1982
), and a universal cooling device for precession cameras, rotation cameras and diffractometers (Hajdu, McLaughlin, Helliwell, Sheldon & Thompson, 1985
). One of the more versatile devices is the cryostream described by Cosier & Glazer (1986
), which uses a pump to effectively separate the liquid-nitrogen supply from the gas outflow; this arrangement eliminates instabilities in the cooling-gas stream; the device works in the range 77.4 to 323.0 K and is commercially available (Oxford Cryosystems, England).
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