| 概 要 |
Matsika教授、Rhee教授の講演概要は以下の通りです。
Sopiridoula Matsika
(Temple University, Departmento of Chemistry・Associate Professor)
"Modeling photoinitiated processes in DNA"
Abstract
The interaction of molecules with light provides a way to investigate molecules. Furthermore, these interactions are important in photochemistry and photobiology. Progress in theoretical chemistry has provided the tools for us to be able to study photoinitiated processes, gain a better understanding of the underlying mechanisms and even predict the photochemical behavior of molecular systems. We use high level electronic structure methods to study photophysical and photochemical events by exploring the potential energy surfaces of molecules and in their ground and excited electronic states. Of particular interest is the photophysics of DNA. DNA absorbs UV radiation which can be used for photochemical reactions leading to dangerous photochemical products. Nevertheless, these molecules have very efficient mechanisms to dissipate the absorbed energy to the environment through radiationless decay mechanisms making them more photostable and protected from the photochemical damage. We will present studies that show how the components of DNA, isolated nucleobases and pi-stacked nucleobases, dissipate the energy. These studies also provide ideas on how to build unnatural bases with desired photophysical properties.
[1]Two Dimensional Fourier-Transform Spectroscopy of adenine and uracil Using Shaped Ultrafast Laser Pulses in the Deep UV", C. Tseng, P. Sandor, T. C. Weinacht and S. Matsika, J. Phys.
Chem. A, submitted, (2011)
[2]Strong Field Molecular Ionization from Multiple Orbitals", M. Kotur, T. Weinacht, C. Zhou and S. Matsika, Phys. Rev. X, submitted, (2011) [3]Combining dissociative ionization pump probe spectroscopy and ab initio calculations to explore excited state dynamics involving conical intersections", S. Matsika, C. Zhou, M. Kotur and T.
Weinacht, Faraday Discussions, accepted, (2011)
Young Min Rhee
（Pohang University of Science and Technology [POSTECH], Department of Chemistry・Assistant Professor）
Dynamics in electronically excited states in biology:
“When a photon goes in or comes out”
Abstract
In this talk, our recent theoretical and computational efforts in describing excited state dynamics in biology will be presented. First, the dynamics of firefly bioluminescence protein-chromophore complex will be discussed based on molecular dynamics and QM/MM simulation results [1]. In fact, from a theoretical point of view, bioluminescence presents many challenges as the involved molecules need to be described with rather expensive quantum chemical methods and with a statistically meaningful ensemble. Focus will be given to how an excited state model can be developed [2] and what new information can be obtained with such a model [1]. We will compare the significance of the mediating role of water molecules around the luminescent chromophore and the tuning role of the protein side chain motion. Next, some theoretical accounts about the quantum coherence in a photosynthetic complex will be shown [3]. Here, we will focus on a formalism called Poisson bracket mapping equation (PBME), and will demonstrate its adequacy in describing photosynthetic systems at physiologically meaningful temperatures. We will also show its merits compared to other approaches together with some preliminary results about the detailed dynamics in a realistic protein complex. The presentation will be closed by considering the prospects in future studies of related phenomena in other biological systems.
[1]Song, C.-I.; Rhee, Y.M. “Dynamics on the electronically excited state surface of the bioluminescent firefly luciferase-oxyluciferin system,” J. Am. Chem. Soc. 2011, 133, 12040.
[2]Song, C.-I.; Rhee, Y.M. “Development of force field parameters for oxyluciferin on its electronic ground and excited states,” Int. J. Quantum Chem, in press, DOI 10.1002/qua.22957.
[3]Kelly, A; Rhee, Y.M. “Mixed quantum-classical description of excitation energy transfer in a model Fenna-Matthews-Olsen complex,” J. Phys. Chem. Lett. 2011, 2, 808.
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