High Energy Accelerator Research Organization (KEK), Japan
Miki Senda has completed her PhD at 2008 from Nagaoka University of Technology. She is an assistant professor of Structural Biology Research Center in High Energy Accelerator Research Organization (KEK). She have several collaborations, in which she has worked as an expert of protein crystallization and crystal quality improvement. She received Oxford Cryosystems Low Temperature Prize at the 63rd Annual meeting of the American Crystallographic Association (ACA) in 2013.
Current X-ray sources of synchrotron radiation enable us to determi ne the crystal structures of proteins even if the crystals were diffracted only to medium or low resolution. However, high-resolution crystal structures ar e still required for the pharmaceutical and biochemical sciences . When obtained crystals were of poor quality and insufficient for crystal structure determination, post-crystallization treatment could improve the crystal quality. Our experiences of crystal structure analyses of hist one chaperon T AF-Iβ, CagA oncoprotein from Helico bacter pylori and GTP sensor PI5P4Kβ showed that crystal soaki ng into cryoprotectants improved crystal-quality (1, 2, 3). Of the three proteins, crystal qualities of CagA and PI5P4Kβ were significantly improved by using more than one cryo-protectant. This method, multi-step soaking method, improved not only the maximum resolution but also success rate of high resolution data collection. Reproducibility of the crystallization is another critical problem in determining crystal structure. Anaerobic crystallization and immediate observation method are effective to improve the reproducibility of the crystallization. We would like to report some examples of the crystallization and crystal quality improvement by our strategy.