Efficient firefly chemi/bioluminescence: evidence for chemiexcitation resulting from the decomposition of a neutral firefly dioxetanone molecule.

Luís Pinto da Silva, A Joel M Santos, Joaquim C G Esteves da Silva

Index: J. Phys. Chem. A 117(1) , 94-100, (2013)

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Abstract

Both experimental and theoretical methodologies were employed in order to study the possibility of excited state oxyluciferin being formed as the result of the decomposition of a neutral dioxetanone. Excitation measurements in water (at different pH values) and in methanol, along with computational calculations, demonstrated that the hydroxyl-benzothiazole group of firefly dioxetanone and six oxyluciferin analogues is only deprotonated in conditions not in line with the firefly bioluminescence reaction. Thus, a new mechanism involving a neutral firefly dioxetanone must be presented in order to explain the chemiexcitation of oxyluciferin. It was also studied for the first time the interaction between a molecule involved in the bioluminescence reaction (neutral firefly dioxetanone) and the real second conformation of firefly luciferase.