| ABSTRACT: |
Through the advancement of computational methods, prediction of transient molecular structures has become relatively easy. In addition, molecular dynamics is now routinely studied on femtosecond time scales using various spectroscopies. However, typical spectroscopic methods cannot provide direct structural information of all nuclear coordinates involved in such dynamical processes, and direct experimental verification of such structures of short lifetime is difficult. Currently, the only available method that provides both direct structural information of atomic scale and ultrafast time
resolution of sub-picosecond and picosecond is time-resolved diffraction by either electrons or x-rays. Here we report direct structural observation of the long-sought bridged radical in solution using time-resolved liquid-phase x-ray diffraction. The structural dynamics spanning picosecond to
microsecond time scale has been experimentally determined in unprecedented structural details. In addition, we further extended this technique to study protein structural dynamics in solution. We obtained time-resolved SAXS (small angle x-ray diffraction) data from model proteins such as myoglobin and hemoglobin and preliminary analysis showed that the 3D structural changes of proteins can be monitored by time-resolved x-ray diffraction even in solution.
References:
1. Ihee et al. "Direct Imaging of Transient Molecular Structures withˇˇUltrafast Diffraction" Science (2001) 291, 458.
2. Ihee et al. "Ultrafast X-ray Diffraction of Transient MolecularˇˇStructures in Solution" Science (2005) 309, 1223.
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