************OWARI COMPLEX SEMINAR LV**************

Title : Theoretical Study of Absorption Spectra 
of Firefly-Luciferin in Aqueous Solutions

Speaker : Dr. Miyabi Hiyama

Affiliation : The Institute for Solid State 
Physics, The University of Tokyo

Date : Mon. Aug. 5th, 16:00 pm (Almost one hour)

Place : 3rd Seminar Room, Graduate School of 
Information Science

Abstract :
Firefly luciferin, referred to as luciferin here, 
is a substrate of bioluminescence reaction and 
converted into oxyluciferin which is the origin 
of this bioluminescence. To understand the 
mechanism of firefly bioluminescence, over the 
last few decades, researchers have investigated 
among others the spectroscopic properties of 
luciferin as an analog of oxyluciferin. In spite 
of the previous experimental and theoretical 
studies, some peaks in the absorption spectra of 
luciferin still remain unassigned. To elucidate 
the origin of absorption spectra of luciferin, we 
have investigated for the excited states of 
luciferin and its conjugate acids and bases by 
performing the time-dependent density functional 
theory calculations (TD－DFT). With the 
theoretical absorption spectra thus obtained, the 
experimental spectra were unequivocally assigned. 
One important result is that the small peak near 
400 nm at pH 1-2 is clarified to be due to the 
excitation of carboxylate anion with N-protonated 
thiazoline ring of firefly luciferin. The details 
of method and results of our study will be 
introduced in the seminar.

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