International
Tables for
Crystallography
Volume F
Crystallography of biological macromolecules
Edited by E. Arnold, D. M. Himmel and M. G. Rossmann

International Tables for Crystallography (2012). Vol. F, ch. 10.1, p. 242   | 1 | 2 |

Section 10.1.1.3. Removal of the solvent layer

H. Hopea* and S. Parkinb

aDepartment of Chemistry, University of California, Davis, One Shields Ave, Davis, CA 95616–5295, USA, and bDepartment of Chemistry, University of Kentucky, Lexington, Kentucky, USA
Correspondence e-mail:  hhope@ucdavis.edu

10.1.1.3. Removal of the solvent layer

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Because of their tendency toward rapid loss of internal solvent, biocrystals rarely survive prolonged exposure to the atmosphere. A solution to this problem was described by Hope (1988[link]), where the solvent is removed while the crystal is submerged in a hydrocarbon oil. After the liquid has been removed, a small drop of oil is allowed to encapsulate the crystal, allowing it to tolerate brief exposure to air. Even under such mild conditions, some crystals still lose water and suffer damage. A remedy for this is to keep the oil saturated with water. One disadvantage of the oil technique is the tendency of loop mounts to carry along too much oil (Teng, 1990[link]), which can cause excessive background scattering. An advantage is that absorption can become nearly isotropic. The most commonly used oil is the polyisobutene Infineum V8512, formerly known as Infineum Parabar 10312, Exxon Paratone-8277 or Paratone-N. Contrary to popular myth, there is nothing magical or mysterious about this particular oil. Important properties are that it is inert, has a useful viscosity, forms a glass on cooling and has a coefficient of thermal expansion which appears to match that of many biocrystals.

References

Hope, H. (1988). Cryocrystallography of biological macromolecules: a generally applicable method. Acta Cryst. B44, 22–26.
Teng, T.-Y. (1990). Mounting of crystals for macromolecular crystallography in a free-standing thin film. J. Appl. Cryst. 23, 387–391.








































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