[Systematic investigation of protein phase behavior with a microfluidic formulator]
>>Published online before print September 27, 2004, 10.1073/pnas.0405847101
Systematic investigation of protein phase behavior with a microfluidic formulator
Carl L. Hansen, Morten O. A. Sommer and Stephen R. Quake *
Department of Applied Physics, California Institute of Technology, MS 128-95, Pasadena, CA 91125
Communicated by Robert H. Austin, Princeton University, Princeton, NJ, August 16, 2004 (received for review February 9, 2004)
We demonstrated a microfluidic device for rapidly generating complex mixtures of 32 stock reagents in a 5-nl reactor. This "formulation chip" is fully automated and allows thousands of experiments to be performed in a single day with minimal reagent consumption. It was applied to systematically study the phase behavior of the protein xylanase over a large and complex chemical space. For each chemical formulation that demonstrated a pronounced effect on solubility, the protein phase behavior was completely mapped in the chip, generating a set of empirical phase diagrams. This ab initio phase information was used to devise a rational crystallization screen that resulted in 72-fold improvement in successful crystallization hits compared with conventional sparse matrix screens. This formulations tool allows a physics-based approach to protein crystallization that may prove useful in structural genomics efforts. <<
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