W0263

Ab initio Crystallogaphic Structure Determination from Protein to Electron Density without Crystal Manipulation. Joseph D. Ng¹, José A. Gavira¹ and Juan M. García-Ruiz²,¹Laboratory for Structural Biology and the Dept. of Biological Sciences, Univ. of Alabama in Huntsville, Huntsville, AL 35899. ²Laboratorio de Estudios Cristalográficos, IACT, CSIC-UGR, Av. Fuentenueva s/n. Granada -18002, Spain, ngj@email.uah.edu, gaviraj@email.uah.edu, jmgruiz@ugr.es.

A quick screening procedure for protein crystals suitable for cryogenic x-ray data collection will be repored. This technique involves the incorporation of an anomalous scatterer for ab initio structural determination by Single Anomalous Scattering techniques without any crystal manipulation at any time. Counter-diffusion crystallization in capillary is a very simple, cost-effective and practical procedure for obtaining protein crystals suitable for X-ray data analysis. Its principles have been derived by well-known concepts coupling the ideas of precipitation and diffusion mass-transport in a restricted geometry. The counter-diffusion process has been used to simultaneously screen for optimal conditions for protein crystal growth, incorporate strong anomalous scattering atoms and mix in cryogenic solutions in a single capillary tube. The crystals obtained in the capillary have been used in situ for X-ray analysis. The implementation of this technique linked to the advancement of current crystallography software leads to a powerful structure-determination method consolidating crystal growth, X-ray data collection and ab initio phase determination into one without crystal manipulation. We review the utilization of counter-diffusion crystallization, its application for x-ray crystallography and undergoing tool development for high-throughput protein structure determination.