Theoretical Study of the Wavelength Selection for the Photocleavage of Coumarin-caged D-luciferin.

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.

Synthesis and quantitative characterization of coumarin-caged D-luciferin.

Caged luciferin compounds of firefly luciferins have recently drawn much attention since firefly bioluminescence, in which D-luciferin acts as a substrate, is widely used in noninvasive gene-expression imaging, studies of in vivo cell trafficking, and the detection of enzyme activity. The objectives of this study are the development of new caged luciferins and the quantitative determination of the photophysical parameters of their photo-decomposition. We synthesized 7-(diethylaminocoumarin)-4-(yl)methyl caged D-luciferin (DEACM-caged D-luciferin) and quantitatively characterized its absorption spectrum, bioluminescence, and photoproducts using chiral HPLC chromatography, as a function of light-irradiation time.