Development of Serial Micro-crystallography

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Abstract A major goal is biomedical science is to move beyond static images of proteins and other biological macromolecules to the internal dynamics underlying their function. This level of study is necessary to understand how these molecules work, to engineer new functions, and to rationally develop therapeutics. In this application, we propose two technological research and development projects that take advantage of the special characteristics of the BioCARS national synchrotron facility to address these goals. In the first, TR&D 1, we describe time-resolved serial micro-crystallography (TR-SMX) coupled with initiation of chemical reactions within molecules. This approach is enabled by the high intensity and tight focusing of X-rays at BioCARS, the availability of a large area, fast detectors, and the use of novel crystal injectors and microfluidic mixers. TR- SMX enables users to observe the dynamics of molecules as they execute their biological function at physiological temperatures. In the second, TR&D 2, we describe electric field-stimulated X-ray crystallography (EFX), a new method visualizing conformational changes within proteins and other biological macromolecules. This method uses external electric fields to induce global, subtle motions of atoms within proteins, with readout using time-resolved X-ray diffraction. Initial work demonstrates the practical application of EFX, and confirms the ability to globally excite motions throughout a protein molecule, including those of biological relevance. Since charges and dipoles are universally present in macromolecules, EFX represents, in principle, a general approach for intramolecular dynamics. We describe several user-based driving biomedical projects and collaborative and service projects that cover a wide range of important problems and push both technologies. User training and active approaches to dissemination to both expert and non-expert, wider audiences will enable broad use of the new technologies by the scientific community.