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Successful Cryocooling of Protein Microcrystalline Samples for Powder Diffraction

Yves Watier 1Jonathan P. Wright Irene Margiolaki 1Andy Fitch 1Mathias Norrman 2Gerd Schluckebier 2

1. European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France
2. Novo Nordisk AS, Copenhagen 00000, Denmark


Modern developments of the powder diffraction technique have allowed the investigation of systems with large unit cells as proteins [1]. Protein powder specimens consist of a large number of randomly oriented diffracting micro-crystals. These micro-crystals are usually formed rapidly by batch crystallization. Frequently, the resolution and quality of the data is limited mainly by rapid deterioration of the protein crystal structure during exposure to the intense synchrotron X-ray beam. In a typical single crystal diffraction experiment radiation damage can be minimized by collecting diffraction data at cryocooled conditions (typically 100K) which requires the addition of a cryoprotecting agent to the protein sample in order to avoid freezing of the mother liquor. In this study, we succeeded in obtaining various cryocooled samples of human insulin at 100K avoiding ice formation. Powder diffraction data were collected at both room temperature and cryocooled conditions (ID31, ESRF, Grenoble, France). As expected both the cryoprotectant and the sample container have a remarkable impact on the data quality. Significant variation of the lattice parameters and peak widths with the type and concentration of cryoprotecting agent  has already been observed and will be presented for the case of insulin. Preliminary data interpretation correlating these changes with the structural and microstructural characteristics of the systems under study will be shown.

[1] Margiolaki, I. & Wight, J. P. Acta Cryst. (2008). A64, 169-180


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Related papers

Presentation: Oral at 11th European Powder Diffraction Conference, Microsymposium 11, by Yves Watier
See On-line Journal of 11th European Powder Diffraction Conference

Submitted: 2008-04-16 09:44
Revised:   2009-06-07 00:48