pH-Dependent absorption spectrum of oxyluciferin analogues in the active site of firefly luciferase.

Nuno Manuel de Almeida Barbosa, Pauline Gosset, Eléonore Réal, Vincent Ledentu, Pascal Didier, Nicolas Ferré

Physical chemistry chemical physics : PCCP 2020 Oct 07

filter terms:

In the quest for the identification of the light emitter(s) responsible for the firefly bioluminescence, the study of oxyluciferin analogues with controlled chemical and electronic structures is of particular importance. In this article, we report the results of our experimental and computational investigation of the pH-dependent absorption spectra characterizing three analogues bound into the luciferase cavity, together with adenosine-monophosphate (AMP). While the analogue microscopic pKa values do not differ much from their reference values, it turns out that the AMP protonation state is analogue-dependent and never doubly-deprotonated. A careful analysis of the interactions evidences the main role of E344 glutamic acid, as well as the flexibility of the cavity which can accommodate any oxyluciferin analogue. The consideration of the absorption spectra suggests that the oxyluciferin enolate form has to be excluded from the list of the bioluminescence reaction products.

Citation

Nuno Manuel de Almeida Barbosa, Pauline Gosset, Eléonore Réal, Vincent Ledentu, Pascal Didier, Nicolas Ferré. pH-Dependent absorption spectrum of oxyluciferin analogues in the active site of firefly luciferase. Physical chemistry chemical physics : PCCP. 2020 Oct 07;22(38):21731-21740