Recently, we have shown that multiple scattering (MS) theory, via the MXAN package, is able to reproduce the experimental X‐ray absorption near edge structure (XANES) data of biological samples, in particular hemeproteins, from the rising edge up to ∼150–200 eV above the edge. In the present work, we illustrate how XANES can be used either as an independent tool to provide bond‐lengths and bond‐angles for a metalloprotein active site in solution, or in combination with X‐ray Diffraction for structural determinations of ligand binding geometry of the same diffracting protein crystal, providing atomic precision even for crystallographic structures solved at > 1.2 Å resolution. At low temperature, XANES can be applied to provide the Fe‐heme structure of trapped intermediate conformations of light triggered processes, and some aspects of the ligand binding dynamics. Very recently, XANES difference spectra have been analyzed to provide the Fe‐heme structure of multiple intermediates of carbonmonoxy‐myoglobin, obtained under different photolysis protocols in solution state.

Topics
Crystal structure, X-ray absorption spectroscopy, X-ray diffraction, Photodissociation, Proteins, Heme group
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© 2007 American Institute of Physics.
2007
American Institute of Physics
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