Femtosecond-to-nanosecond dynamics of flavin mononucleotide monitored by stimulated Raman spectroscopy and simulations. Issue 12 (29th January 2020)

• Record Type: Journal Article
• Authors: Andrikopoulos, Prokopis C.; Liu, Yingliang; Picchiotti, Alessandra; Lenngren, Nils; Kloz, Miroslav; Chaudhari, Aditya S.; Precek, Martin; Rebarz, Mateusz; Andreasson, Jakob; Hajdu, Janos; Schneider, Bohdan; Fuertes, Gustavo
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 12(2020)
• Page Start: 6538
• Page End: 6552
• Publication Date: 2020-01-29
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c9cp04918e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The ultrafast excited-state dynamics of flavin mononucleotide (FMN) was monitored upon light irradiation by a hybrid experimental/computational approach. Abstract : Flavin mononucleotide (FMN) belongs to the large family of flavins, ubiquitous yellow-coloured biological chromophores that contain an isoalloxazine ring system. As a cofactor in flavoproteins, it is found in various enzymes and photosensory receptors, like those featuring the light-oxygen-voltage (LOV) domain. The photocycle of FMN is triggered by blue light and proceeds via a cascade of intermediate states. In this work, we have studied isolated FMN in an aqueous solution in order to elucidate the intrinsic electronic and vibrational changes of the chromophore upon excitation. The ultrafast transitions of excited FMN were monitored through the joint use of femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption spectroscopy encompassing a time window between 0 ps and 6 ns with 50 fs time resolution. Global analysis of the obtained transient visible absorption and transient Raman spectra in combination with extensive quantum chemistry calculations identified unambiguously the singlet and triplet FMN populations and addressed solvent dynamics effects. The good agreement between the experimental and theoretical spectra facilitated the assignment of electronic transitions and vibrations. Our results represent the first steps towards more complex experiments aimed at tracking structural changes of FMN embedded in light-inducible proteins upon photoexcitation.