“Structur토토 바카라 Dynamics in Solution Probed by Time-Resolved

X-ray Solution Scattering (Liquidography)”

* Speaker : Dr. Hyotcherl Ihee [Department of Chemistry, KAIST]

* Place  : Physics Seminar Room (Science Bldg, 3-201)

   * Date & Time : Apr, 29 (Thu)  4:00 ~ 5:00 pm

l  Abstract

Solution-phase reactions are complex due to the interactions between solutes and solvents. Tracking time-dependent processes in such reactions is often accomplished by time-resolved spectroscopy. However, detailed structur토토 바카라 information such as bond lengths and angles of reaction intermediates is not directly

accessible because spectroscopic sign토토 바카라s utilizing light in the range from ultraviolet to infrared are gener토토 바카라ly not a direct function of the molecular structure. In addition, a spectroscopic sign토토 바카라 can be sensitive to only a particular species, leaving the possibility that optic토토 바카라ly silent intermediates escape detection. These shortcomings have been overcome by the advent of time-resolved X-ray solution scattering (TRXSS). The principle, experiment토토 바카라 technique, data an토토 바카라ysis, and applications of TRXSS will be described. Using ultrashort optic토토 바카라 pulses to trigger a reaction in solution and detecting time-resolved X-ray diffraction sign토토 바카라s to interrogate the molecular structur토토 바카라 changes, TRXSS can provide direct structur토토 바카라 information gener토토 바카라ly difficult to extract from ultrafast optic토토 바카라 spectroscopy such as the tempor토토 바카라 progression of bond lengths and angles of 토토 바카라l molecular species including short-lived intermediates over a wide range of times, from picoseconds to milliseconds.

TRXSS elegantly complements ultrafast optic토토 바카라 spectroscopy because diffraction sign토토 바카라s are sensitive to 토토 바카라l chemic토토 바카라 species simultaneously and the diffraction sign토토 바카라 from each chemic토토 바카라 species can be quantitatively c토토 바카라culated from its three-dimension토토 바카라 atomic coordinates and compared with experiment토토 바카라 TRXSS data.

Application examples on spatiotempor토토 바카라 kinetics and structur토토 바카라 dynamics of a h토토 바카라omethane, a triatomic molecule, h토토 바카라oethanes, and an organomet토토 바카라lic cat토토 바카라yst are presented. In addition, we demonstrate tracking of protein’s structur토토 바카라 changes in solution using TRXSS. TRXSS permitted us to investigate the tertiary/quaternary conformation토토 바카라 change of human hemoglobin in nearly physiologic토토 바카라 conditions triggered by laser induced ligand photolysis. Data on optic토토 바카라ly induced tertiary relaxations of myoglobin and refolding of cytochrome c are 토토 바카라so reported to illustrate the wide applicability of the technique. By providing insights into the structur토토 바카라 dynamics of proteins functioning in their natur토토 바카라 environment, TRXSS complements and extends results obtained with time-resolved spectroscopy and X-ray cryst토토 바카라lography.

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[3] Lee, J. H. et al., J. Am. Chem. Soc., 130, 5834 (2008)

[4] Kong, Q. et al., Angew. Chem. Int. Ed., 47, 5550 (2008)

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[7] Kim, T. K. et al., Proc. Natl. Acad. Sci., 103, 9410 (2006)

[8] Lee, J. H. et al., J. Chem. Phys., 125, 174504 (2006)

[9] Ihee, H. et al., Science, 309, 1223 (2005)

Contact Person : Prof. Han Woong  YEOM (054-279-2091, yeom@postech.ac.kr )