Deciphering the pH-dependence of ground- and excited-state equilibria of thienoguanine.

Fiche publication


Date publication

mars 2020

Journal

Physical chemistry chemical physics : PCCP

Auteurs

Membres identifiés du Cancéropôle Est :
Pr MELY Yves, Pr DIDIER Pascal


Tous les auteurs :
Didier P, Kuchlyan J, Martinez-Fernandez L, Gosset P, Léonard J, Tor Y, Improta R, Mély Y

Résumé

The thienoguanine nucleobase (thGb) is an isomorphic fluorescent analogue of guanine. In aqueous buffer at neutral pH, thGb exists as a mixture of two ground-state H1 and H3 keto-amino tautomers with distinct absorption and emission spectra and high quantum yield. In this work, we performed the first systematic photophysical characterization of thGb as a function of pH (2 to 12). Steady-state and time-resolved fluorescence spectroscopies, supplemented with theoretical calculations, enabled us to identify three additional thGb forms, resulting from pH-dependent ground-state and excited-state reactions. Moreover, a thorough analysis allowed us to retrieve their individual absorption and emission spectra as well as the equilibrium constants which govern their interconversion. From these data, the complete photoluminescence pathway of thGb in aqueous solution and its dependence as a function of pH was deduced. As the identified forms differ by their spectra and fluorescence lifetime, thGb could be used as a probe for sensing local pH changes under acidic conditions.

Référence

Phys Chem Chem Phys. 2020 Mar 25;: