Interaction of aromatic compounds with Photobacterium leiognathi luciferase: fluorescence anisotropy study.

The time-resolved and steady-state fluorescence techniques were employed to elucidate possible interactions of four aromatic compounds (anthracene, POPOP, MSB and 1,4-naphthalendiol) with bacterial luciferase. Fluorescence spectra and fluorescence anisotropy decays of these compounds were studied in ethanol, water-ethanol solutions and in the presence of bacterial luciferase. Shifts of fluorescent spectra and differences in rotational correlation times are interpreted in terms of weak (hydrophobic) interactions of the molecules with the enzyme. These interactions suggest the feasibility of intermolecular energy transfer by an exchange resonance mechanism with a collision-interaction radius as a way of excitation of these compounds in the reaction catalysed by bacterial luciferase.