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Noguchi, Yoshifumi*; Hiyama, Miyabi*; Shiga, Motoyuki; Akiyama, Hidefumi*; Sugino, Osamu*
Journal of Chemical Physics, 153(20), p.201103_1 - 201103_6, 2020/11
Times Cited Count：2 Percentile：11.43(Chemistry, Physical)Stabilizing mechanisms of three isomers of the aqueous oxyluciferin in the first excited state were investigated using first-principles molecular dynamics simulations. Only the phenolate-keto isomer became attracted to the water molecules in its excited state and was stabilized by increasing the number of hydrogen bonds with nearby water molecules. The most stable isomer in the excited state was the phenolate-keto, and the phenolate-enol and phenol-enolate isomers were higher in energy by 0.38 eV and 0.57 eV, respectively, than the phenolate-keto. This was in contrast to the case of ground state in which the phenolate-enol was the most stable isomer.
Hiyama, Miyabi*; Shiga, Motoyuki; Koga, Nobuaki*; Sugino, Osamu*; Akiyama, Hidefumi*; Noguchi, Yoshifumi*
Physical Chemistry Chemical Physics, 19(15), p.10028 - 10035, 2017/04
Times Cited Count：7 Percentile：31.12(Chemistry, Physical)In this study, the effect of hydration on the absorption spectra of oxyluciferin anion isomers in an aqueous solution is investigated for elucidating the influence of characteristic hydration structures. Using a canonical ensemble of hydration structures obtained from first-principles molecular dynamics simulations, the instantaneous absorption spectra of keto-, enol-, and enolate-type aqueous oxyluciferin anions at room temperature are computed from a collection of QM/MM calculations using an explicit solvent. It is demonstrated that the calculations reproduce experimental results concerning spectral shifts and broadening, for which traditional methods based on quantum chemistry and the Franck-Condon approximation fail because of the molecular vibrations of oxyluciferin anions and dynamical fluctuations of their hydration structures.
Noguchi, Yoshifumi*; Hiyama, Miyabi*; Shiga, Motoyuki; Sugino, Osamu*; Akiyama, Hidefumi*
Journal of Physical Chemistry B, 120(34), p.8776 - 8783, 2016/09
Times Cited Count：6 Percentile：15.29(Chemistry, Physical)We investigated the stability of oxyluciferin anions (keto, enol, and enolate isomers) in aqueous solution at room temperature by performing a nanosecond time scale first-principles molecular dynamics simulation. In contrast to all previous quantum chemistry calculations, which suggested the keto-type to be the most stable, we show that the enol-type is slightly more stable than the keto-type, in agreement with some recent experimental studies. The simulation highlights the remarkable hydrophobicity of the keto-type by the cavity formed at the oxyluciferin-water interface as well as a reduction in hydrophobicity with the number of hydrating water molecules. It is therefore predicted that the isomeric form in a hydrated cluster is size-dependent.
