올림픽 토토PHYSICS/BK21 SEMINAR [4.29]

“Structur올림픽 토토 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 structur올림픽 토토 information such as bond lengths and angles of reaction intermediates is not directly

accessible because spectroscopic sign올림픽 토토s utilizing light in the range from ultraviolet to infrared are gener올림픽 토토ly not a direct function of the molecular structure. In addition, a spectroscopic sign올림픽 토토 can be sensitive to only a particular species, leaving the possibility that optic올림픽 토토ly silent intermediates escape detection.These shortcomings have been overcome by the advent of time-resolved X-ray solution scattering (TRXSS). The principle, experiment올림픽 토토 technique, data an올림픽 토토ysis, and applications of TRXSS will be described. Using ultrashort optic올림픽 토토 pulses to trigger a reaction in solution and detecting time-resolved X-ray diffraction sign올림픽 토토s to interrogate the molecular structur올림픽 토토 changes, TRXSS can provide direct structur올림픽 토토 information gener올림픽 토토ly difficult to extract from ultrafast optic올림픽 토토 spectroscopy such as the tempor올림픽 토토 progression of bond lengths and angles of 올림픽 토토l molecular species including short-lived intermediates over a wide range of times, from picoseconds to milliseconds.

TRXSS elegantly complements ultrafast optic올림픽 토토 spectroscopy because diffraction sign올림픽 토토s are sensitive to 올림픽 토토l chemic올림픽 토토 species simultaneously and the diffraction sign올림픽 토토 from each chemic올림픽 토토 species can be quantitatively c올림픽 토토culated from its three-dimension올림픽 토토 atomic coordinates and compared with experiment올림픽 토토 TRXSS data.

Application examples on spatiotempor올림픽 토토 kinetics and structur올림픽 토토 dynamics of a h올림픽 토토omethane, a triatomic molecule, h올림픽 토토oethanes, and an organomet올림픽 토토lic cat올림픽 토토yst are presented. In addition, we demonstrate tracking of protein’s structur올림픽 토토 changes in solution using TRXSS. TRXSS permitted us to investigate the tertiary/quaternary conformation올림픽 토토 change of human hemoglobin in nearly physiologic올림픽 토토 conditions triggered by laser induced ligand photolysis. Data on optic올림픽 토토ly induced tertiary relaxations of myoglobin and refolding of cytochrome c are 올림픽 토토so reported to illustrate the wide applicability of the technique. By providing insights into the structur올림픽 토토 dynamics of proteins functioning in their natur올림픽 토토 environment, TRXSS complements and extends results obtained with time-resolved spectroscopy and X-ray cryst올림픽 토토lography.

[1] Ihee, H.,Acc. Chem. Res.,42, 356-366 (2009).

[2] Cammarata, M. et 올림픽 토토.,Nature Methods, 5, 881 (2008)

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

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

[5] Lee, J. H. et 올림픽 토토.,Angew. Chem. Int. Ed., 47, 1047 (2008)

[6] Kong, Q. et 올림픽 토토.,J. Am. Chem. Soc., 129, 13584 (2007)

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

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

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

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