title: Reverse Stability of Oxyluciferin Isomers in Aqueous Solutions.
abstract: 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.
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Miyabi
authors.initials: M
authors.lastname: Hiyama
authors.affiliation: Center for Computational Science and E-Systems, Japan Atomic Energy Agency , 148-4 Kashiwanoha Campus, 178-4 Wakashiba, Kashiwa, Chiba 277-0871, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Shiga
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Sugino
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Akiyama