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Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate
Published on: April 6, 2022
Light-triggered proton and electron transfer in flavin cofactors
1Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
The Journal of Physical Chemistry. A
|April 25, 2008
Summary
Femtosecond spectroscopy reveals pH-dependent behavior of flavin cofactors. Protonation significantly alters flavin excited states, influencing their dynamics and lifetimes.
Area of Science:
- Photochemistry
- Biophysical Chemistry
- Spectroscopy
Background:
- Flavin cofactors like FAD and FMN are crucial in biological redox reactions.
- Understanding their excited-state properties is key to elucidating their function.
Purpose of the Study:
- To characterize the pH-dependent behavior of flavin-adenine dinucleotide (FAD) and flavin mononucleotide (FMN) excited states for the first time.
- To investigate the influence of protonation on flavin excited-state dynamics and electronic properties.
Main Methods:
- Femtosecond transient absorption spectroscopy was employed.
- Characterization of flavin excited states across three protonation states (Fl(-), Fl, FlH(+)).
Main Results:
- Flavin mononucleotide (FMN) protonation states (Fl and Fl(-)) show similar excited-state absorption but differing lifetimes, with Fl(-) being shorter.
- Flavin-adenine dinucleotide (FAD) exhibits pH-dependent conformational changes (open vs. stacked) that control its excited-state deactivation dynamics.
- Protonation sites differ between ground and excited states, and FAD's behavior converges with FMN at low/high pH in its 'open' conformation.
Conclusions:
- Protonation significantly modifies the electronic properties and excited-state lifetimes of flavin chromophores.
- FAD's conformational flexibility dictates its excited-state dynamics, with transitions occurring around pH 3 and pH 10 due to adenine and flavin deprotonation, respectively.
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