Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment

L. VALLE; F. E. MORÁN VIEYRA; C. D. BORSARELLI

Photochemical and Photobiological Sciences

ROYAL SOC CHEMISTRY

Año: 2012 vol. 11 p. 1051 - 1061

1474-905X

The singlet and triplet excited states properties of lumiflavin (LF), riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) dissolved in reverse micelles (RMs) solutions of sodium docusate (AOT) in n-hexane were evaluated by steady-state and time-resolved absorption and fluorescence spectroscopy. The variation of several photophysical parameters was analyzed as a function of the amount of dispersed water in the RMs. The results indicate that hydrogen-bonding interactions between the isoalloxazine ring of the flavins with water molecules at the internal micellar, rather than solely local viscosity and/or polarity effects, plays a crucial role on the modulation of the singlet and triplet excited state properties, such as emitting excited state species, triplet lifetimes, etc. It is also proposed that AOT RMs with low water content can be useful artificial media for mimicking of environmental properties of active sites of flavoproteins.