공공기관 경영정보 공개시스템
ALL Public Information in One
- FIELD
- Comp.Sciences:Life Science
- DATE
- Jan 15 (Thu), 2026
- TIME
- 11:00 ~ 12:00
- PLACE
- 8101
- SPEAKER
- Young Min Rhee
- HOST
- INSTITUTE
- KAIST
- TITLE
- Ultrafast twisting dynamics of the photoactive yellow protein chromophore
- ABSTRACT
- Photoactive yellow protein (PYP) has been considered as a prototypical system for representing photoreceptor proteins, which convert photon energies to mechanical movements. It shows a characteristic photocycle driven by a trans-to-cis isomerization of its core chromophore. While the chromophore can undergo such a change in an ultrafast manner, how it interconverts between the two conformations strongly depends on its environment. Indeed, the isomerization pathway changes drastically as the chromophore becomes embedded in the protein environment. Many theoretical and experimental studies have been performed to provide molecular level understanding on this aspect, but they have often reached inconsistent conclusions. The key difficulties lie in part in the ultrafast nature that hinders experimental elucidation and the strong electron correlation along the isomerization path that makes the electronic structure calculations time-consuming. Indeed, from the viewpoint of computational research, following its dynamics calls for performing simulations, which requires repeated electronic structure calculations at continually varying geometries. Here, we will discuss how this issue can be tackled by the use of interpolation mechanics / molecular mechanics (IM/MM) for building the ground and the excited state potential energy surfaces of the protein complex. With the actual simulation results obtained with IM/MM, we will see how the twisting dynamics in PYP is governed by its hydrogen bonding as well as its internal features with some dihedral angles. Indeed, properly handling such aspects requires very careful construction of the PES model for the system, and for this purpose, we introduce a new weighting scheme of IM that can automatically put more weights on more important degrees of freedom. We will see that the PES model can explain experimentally reported kinetics quite well with a number of rate parameters that originate from different types physical interactions of the chromophore. Interestingly, the hydrogen bonding environment of the chromophore turns out to be the most important key factor out of many different environmental interactions.
- FILE