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Theoretical Study of the Wavelength Selection for the Photocleavage of Coumarin-caged D-luciferin |
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| Authors: | Junko Usukura Miyabi Hiyama Maki Kurata Yuji Hazama Xing-Ping Qiu Francoise M Winnik Hidefumi Akiyama Nobuaki Koga |
| Institution: | 1. Institute for Solid Physics, University of Tokyo, Kashiwa, Japan;2. Graduate School of Science and Technology, Gunma University, Kiryu, Japan;3. Institute for Solid Physics, University of Tokyo, Kashiwa, Japan
AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), Kashiwa, Japan;4. Département de Chimie, Université de Montréal, Montréal, Canada;5. Department of Chemistry, University of Helsinki, Helsinki, Finland International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan;6. Graduate School of Informatics, Nagoya University, Nagoya, Japan |
| Abstract: | The equilibrium structures and optical properties of the photolabile caged luciferin, (7-diethylaminocoumarin-4-yl)methyl caged D-luciferin (DEACM-caged D-luciferin), in aqueous solution were investigated via quantum chemical calculations. The probable conformers of DEACM-caged D-luciferin were determined by potential energy curve scans and structural optimizations. We identified 40 possible conformers of DEACM-caged D-luciferin in water by comparing the Gibbs free energy of the optimized structures. Despite the difference in their structures, the conformers were similar in terms of assignments, oscillator strengths and energies of the three low-lying excited states. From the concentrations of the conformers and their oscillator strengths, we obtained a theoretical UV/Vis spectrum of DEACM-caged D-luciferin that has two main bands of shape nearly identical to the experimental UV/Vis spectrum. The absorption bands with maxima ~ 384 and 339 nm were attributed to the electronic excitations of the caged group and the luciferin moiety, respectively, by analysis of the theoretical UV/Vis spectrum. Furthermore, the analysis showed that DEACM-caged D-luciferin is excited in the caged group only by light of wavelength ranging within 400–430 nm, which is in the long-wavelength tail of the 384 nm band. This should be tested to lower damage upon photocleavage. |
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