New X-Ray Measurement Method for Minimizing Deterioration of Protein Crystals (Press Release)
- Release Date
- 16 Aug, 2013
- BL38B1 (Structural Biology III)
Japan Synchrotron Radiation Research Institute (JASRI)
Rigaku Corporation
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The Structural Biology Group of JASRI has developed a new measurement method for confirming the state of protein crystals and improving their crystal quality in real time while minimizing the deterioration of the crystals. In the X-ray diffraction measurement for the structural analysis of protein crystals, the crystals are cooled to an ultralow temperature of -180 °C or below to reduce the radiation-induced damage to the crystals. However, because the crystals often deteriorate during cooling, trial-and-error processes are required to optimize the conditions for the treatment of crystals. Therefore, the development of a versatile and efficient treatment method has been desired. In the method developed in this study, the states of crystals are slowly changed to those appropriate for cooling by coating the crystals with a water-soluble polymer glue and by blowing humidity-controlled gas onto the crystals. This method enables most crystals to be maintained in a stable state. Even crystals that have been difficult to handle can be cooled while maintaining their quality stably. This method brings about a marked improvement in the prevention of deterioration of protein crystals. This method will markedly increase the efficiency of the structural analysis of protein crystals carried out by researchers in Japan and abroad, leading to significant progress in drug research and development and in research on the treatment of intractable diseases. With the aim of disseminating this method, the research group of this study in collaboration with Rigaku Corporation has undertaken the development of a new experimental apparatus. These results were achieved by Seiki Baba (research scientist), Takashi Kumasaka (group leader), and other researchers of JASRI. Their achievements were published in the scientific journal Acta Crystallographica Section D: Biological Crystallography, published by the International Union of Crystallography based in Britain, on 1 September 2013. Publication: |
<<Figures>>
glue-coating (HAG) method and state of mounted crystals
(a) Apply polyvinyl alcohol (PVA) glue to a loop tool.
(b) Pick up a crystal using the loop tool with PVA glue film.
(c) The crystal adhered to the film is coated with the PVA glue. PVA glue is saturated by controlling humidity to fix the crystals.
Crystals are mounted on a rotating stage and humidity-controlled gas onto the crystals during the experiment.
method using cryoprotectants and (b) those frozen by the HAG method
The crystals frozen by a conventional method are severely damaged causing disturbances in the diffraction image, whereas those frozen by the HAG method are not damaged.
Changes in the length of crystal lattices of three different egg-white lysozyme crystals due to dehydration and hydration are examined. There is a high correlation between humidity and lattice constant. (a) Humidity decreases to a point at which crystals are damaged. (b) and (c) humidity also decreases and then increases before reaching the point at which damage in (a) is observed.
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For more information, please contact: Dr. Takashi Kumasaka (JASRI) |
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