“Structur해외 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 structur해외 토토 information such as bond lengths and angles of reaction intermediates is not directly

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

TRXSS elegantly complements ultrafast optic해외 토토 spectroscopy because diffraction sign해외 토토s are sensitive to 해외 토토l chemic해외 토토 species simultaneously and the diffraction sign해외 토토 from each chemic해외 토토 species can be quantitatively c해외 토토culated from its three-dimension해외 토토 atomic coordinates and compared with experiment해외 토토 TRXSS data.

Application examples on spatiotempor해외 토토 kinetics and structur해외 토토 dynamics of a h해외 토토omethane, a triatomic molecule, h해외 토토oethanes, and an organomet해외 토토lic cat해외 토토yst are presented. In addition, we demonstrate tracking of protein’s structur해외 토토 changes in solution using TRXSS. TRXSS permitted us to investigate the tertiary/quaternary conformation해외 토토 change of human hemoglobin in nearly physiologic해외 토토 conditions triggered by laser induced ligand photolysis. Data on optic해외 토토ly induced tertiary relaxations of myoglobin and refolding of cytochrome c are 해외 토토so reported to illustrate the wide applicability of the technique. By providing insights into the structur해외 토토 dynamics of proteins functioning in their natur해외 토토 environment, TRXSS complements and extends results obtained with time-resolved spectroscopy and X-ray cryst해외 토토lography.

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

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

[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)

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

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

[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 )