HT1 L3: Cryo-cooling: why and how?

HT1: Crystallization

L3 (Lecture): Cryo-cooling: why and how?

Elspeth Garman
Biochemistry Department, Oxford University
South Parks Road, Oxford
OX1 3QU, U.K.
E-mail:elspeth.garman@bioch.ox.ac.uk

When a crystal has finally been obtained, the next stage in the structure determination pipeline is to prepare it for a diffraction test either at room temperature or 100 K. Often this step is given little thought, and the deleterious effects of various unfavorable crystal handling and cryo-protection protocols are not appreciated. In many laboratories, a ‘standard’ route is used, which has worked for other protein crystals in the past. However, entrenched and accepted practices are not necessarily the optimum ones for a particular problem, and may not work at all for your protein. This lecture will follow the crystal from growth drop to goniometer, through the identification of a suitable stabilizing buffer, a benign cryo-protectant buffer, and an effective cooling protocol, emphasizing the physical principles which affect the outcome (resolution of diffraction and mosaic spread: with the aim of maximizing the former and minimizing the latter) [1,2,3]. The practical aspects will be covered during the hands-on session.

References:

[1] Macromolecular Cryocrystallography. Elspeth F. Garman and Thomas Schneider, J.Appl.Cryst. (1997) 30, 211-237
[2] Cool Data: Quantity and Quality. Elspeth F. Garman.  Acta Cryst. (1999) D55, 1641-1653
[3] Practical Macromolecular Cryocrystallography. James W. Pflugrath. Acta Cryst (2015) F71, 622-642