Dear Colleagues,
I'm delighted to announce that Dr. Jose Gavira will give a scientific presentation in Rigaku Crystallization Webinars on November 12th, 2013, 8:00am Pacific Standard Time. The webinar is free to attend and all are welcome. You can register it through our web page, http://www.rigakuautomation.com/webinars. Here is the detail of the presentation: " Capillary counter-diffusion methods for protein crystallization: Screening and crystal improvement Presenter: Dr. José A. Gavira, Laboratorio de Estudios Cristalográficos, IACT, (CSIC - UGR), Avd. de las Palmeras, 4, 18100 Armilla (Granada), Spain Date and time: Tuesday, November 12th, 2013, 8:00am Pacific Standard Time Protein crystallization techniques used in Structural Biology laboratories are typically the vapour diffusion (hanging or sitting-drop) and/or micro-bath (batch) under oil. In vapour diffusion technique the slow evaporation of a drop, obtained by mixing protein and precipitant solutions, bring the system into the supersaturation region at a fixed rate while in batch methodologies protein and precipitating solutions are immediate mixed to reach the desired supersaturation. Both techniques have inherent buoyancy driven convection and consequently crystals are grown in a heterogeneous environment compromising uniform crystal growth and quality. Both chaotic mixing and convection can be reduced or eliminated when the crystallization process is allowed to proceed by diffusively mixing the protein and precipitant solutions. This effect can be achieve by the liquid-liquid diffusion or free-interface diffusion techniques in which protein and precipitant solutions are allowed to diffuse one against each other in any media permitting diffusive mass transport (gels, capillaries, microfluidic devices or microgravity). There are different ways to implement this technique. Among them, the most effective configuration proven to be useful for growing macromolecules crystals is the counter-diffusion (CD) technique [1-3]. Unlike other techniques aimed at finding initial conditions close to equilibrium, counterdiffusion looks for initial high values of supersaturation thus provoking even the formation of amorphous precipitates at the earliest stages of the experiment. Then, by using a long protein chamber, the technique exploits the simultaneous event of diffusion and crystallization giving rise to a supersaturation gradient along the length of the crystallization chamber. In this talk we will illustrate with several examples the use of the capillary counter diffusion technique to screen for initial crystallization conditions, to improve protein crystal quality or to soak any additive including heavy atoms, cryo-protectants, etc. [2-4]. Furthermore the advantage of in situ X-ray data collection without crystal handling will be shown [4]. References: 1. Garcia-Ruiz, J. M.; Charles W. Carter, J.; Sweet, R. M., Counterdiffusion Methods for Macromolecular Crystallization. Methods in Enzymology 2003, 368, 130. 2. Ng, J. D.; Gavira, J. A.; Garcia-Ruiz, J. M., Protein crystallization by capillary counterdiffusion for applied crystallographic structure determination. JBC 2003, 142, 218. 3. Otalora, F.; Gavira, J. A.; Ng, J. D.; Garcia-Ruiz, J. M., Counterdiffusion methods applied to protein crystallization. Progress in biophysics and molecular biology 2009, 101, 26. 4. Gavira, J. A.; Toh, D.; Lopez-Jaramillo, J.; Garcia-Ruiz, J. M.; Ng, J. D., Ab initio crystallographic structure determination of insulin from protein to electron density without crystal handling. Acta Crystallographica Section D: Biological Crystallography 2002, 58, (7), 1147. Thank you, Jian Xu, Ph.D. Director of Scientific Marketing Rigaku Automation, Inc. jian...@rigaku.com<mailto:jian...@rigaku.com> www.rigakuautomation.com<http://www.rigakuautomation.com>
