Estimation of energy of the upper electron-excited states of the bacterial bioluminescent emitter

The hypothesis of activity of the upper electron-excited states of the bacterial bioluminescent emitter was verified using dye molecules as foreign energy acceptors. Six compounds were selected having fluorescent state energies ranging from 25 700 to 32 000 cm−1 (anthracene, pyrene, 1.4-bis(5-phenyloxasol-2-yl)benzene (POPOP), p-bis(o-methylstyryl)benzene (MSB), 2-methoxy-naphtalene, p-terphenyl), exceeding that of the bioluminescent emitter (22 000 cm−1). Their absorption spectra do not overlap with the bioluminescence spectrum; the trivial light absorption and the intermolecular resonance S–S energy transfer were excluded. Bacterial bioluminescent spectra of the coupled enzyme system NADH:FMN–oxidoreductase–luciferase in the presence of MSB were presented as an example. The weak sensitized fluorescence of MSB was registered. The results obtained have confirmed the activity of the energetic precursor in the bacterial bioluminescence. Its energy can be located in the interval of 26 000–27 000 cm−1.