Elucidation of Protein -Precipitant Phase Diagrams and Their Link to Crystal Quality
In sum, we report new evaporation- and dilution-based protocols that will enable structural biologist to rapidly determine the phase diagram (e.g. solubility boundary, metastable zone width) of proteins of unknown structure using a very small sample volume. The knowledge of phase diagram of a protein/precipitant system thus obtained will be useful in obtaining high quality crystals for X-ray diffraction studies. Moreover, we use theory to compare different protein molecules on a generalized phase diagram using the solubility data obtained from our experiments. The comparison of the solubility boundary and the metastable boundary on the same footing will provide a reasonable estimate of the metastable zone width, which will aid crystallographers in screening conditions conducive for protein crystallization. We also develop a kinetic model that describes the competition between the rates of supersaturation, crystal nucleation and crystal growth occurring in the regulated-evaporation crystallization process. The knowledge of these rates coupled with the knowledge of the phase diagram of a protein/precipitant system will enable crystallographers to predict a priori the outcome of an experiment performed in an evaporation-based crystallization platform.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign