pH‐Dependent Absorption Spectrum of Oxyluciferin Analogues in the Presence of Adenosine Monophosphate

Nuno Manuel de Almeida Barbosa (1) , Madjid Zemmouche (2) , Pauline Gosset (3) , Cristina García‐iriepa (2) , Vincent Ledentu (1) , Isabelle Navizet (2) , Pascal Didier (4) , Nicolas Ferré (1)

1 ICR - Institut de Chimie Radicalaire
2 MSME - Laboratoire de Modélisation et Simulation Multi Echelle
3 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
4 LBP - Laboratoire de Biophotonique et Pharmacologie - UMR 7213

The photophysical properties of oxyluciferin, the light emitter responsible for firefly bioluminescence, are pH-dependent. One of the potential proton accep-tor/donor is adenosine monophosphate (AMP). We have studied three oxylu-ciferin synthetic analogues with or without AMP, in water, in the pH=5 to 11 range, using both experimental steady-state absorption spectroscopy or the recently developed computational protocol that uses constant pH molecular dynamics and then hybrid QM/MM calculations (CpHMD-then-QM/MM). The latter features a systematic investigation of all the protonation microstates using molecular dynamics simulations coupled to thousands hybrid QM/MM vertical excitation energies. Our results demonstrate that AMP does not significantly modify the visible light absorption of the analogues, whatever the pH value. We also show that CpHMD-then-QM/MM is capable to qualitatively reproduce the pH-dependent absorption spectrum of the analogues, despite the employed low QM level of theory.

Keywords: absorption spectroscopy; computational photochemistry; multiscale simulations; oxyluciferin; pH dependency

Domains: Chemical Sciences; Theoretical and/or physical chemistry

Nuno Manuel de Almeida Barbosa, Madjid Zemmouche, Pauline Gosset, Cristina García‐iriepa, Vincent Ledentu, et al.. pH‐Dependent Absorption Spectrum of Oxyluciferin Analogues in the Presence of Adenosine Monophosphate. ChemPhotoChem, 2019, ⟨10.1002/cptc.201900150⟩. ⟨hal-02409332⟩