Femtosecond pump-probe experiments on trapped flavin: Optical control of dissociation

Abstract

Femtosecond pump-probe experiments are performed on flavin biomolecules isolated in an ion trap. Mass spectra of the photoinduced fragments show that the fragmentation pathways can be modified using two-color two-photon excitation. In particular, when an infrared probe pulse ͑810 nm͒ is added subsequent to the first excitation step ͑excitation of the S 1 state of flavin mononucleotide at 405 nm͒, branching ratios between lumichrome and lumiflavin production are inverted relative to the single excitation case.

Flavinium Catalysed Photooxidation: Detection and Characterization of Elusive Peroxyflavinium Intermediates

“…Next, we have determined structures of the detected intermediates by helium tagging infrared photodissociation (IRPD) spectroscopy. [13][14][15] Thec orrect structures were assigned based on comparison of the experimental data with theoretical IR spectra of possible isomers.W ep resent the results for [1a+ 2H,2 O] + here;t he results for other complexes are shown in the Supporting Information ( Figure S39), as their structures are analogous.…”

IRMPD spectroscopy of metalated flavins: structure and bonding of Mq+–lumichrome complexes (Mq+ = Li+–Cs+, Ag+, Mg2+)

“…Basic properties of flavins, their ground-state structure, their stability, and their interaction with metal ions and solvent must be characterized to generate a consistent molecular-level description of their activity and function. 16 However, due to their difficult preparation in the gas phase, experiments on isolated flavins have not been performed until recently, [17][18][19] and studies of their metal and solvent adducts are completely lacking. The few available studies include photo-and collision-induced fragmentation of protonated flavin mononucleotide (FMN), 19 a fluorescence spectrum of lumichrome (LC) in superfluid He droplets, 20 and the determination of the proton affinity of lumiflavin (LF) by mass spectrometry.…”

“…16 However, due to their difficult preparation in the gas phase, experiments on isolated flavins have not been performed until recently, [17][18][19] and studies of their metal and solvent adducts are completely lacking. The few available studies include photo-and collision-induced fragmentation of protonated flavin mononucleotide (FMN), 19 a fluorescence spectrum of lumichrome (LC) in superfluid He droplets, 20 and the determination of the proton affinity of lumiflavin (LF) by mass spectrometry. 17 Moreover, the preferred protonation site of a variety of fundamental protonated flavins, including LC, LF, riboflavin (RF, vitamin B 2 ), and FMN, have recently been determined by infrared multiphoton dissociation (IRMPD) spectroscopy and quantum chemical calculations.…”

Observation of Near-Threshold Resonances in the Flavin Chromophore Anions Alloxazine and Lumichrome

“…[5][6][7] Despite the importance of flavins, studies of the electronic properties of isolated (i.e. gas-phase) flavins have been extremely sparse until very recently, [8][9][10] particularly compared to the large number of studies where the chromophore is studied in solution. [11][12][13] This is surprising as the gas-phase is an appropriate medium in which to study intrinsic properties of such chromophores, 14 which typically sit entirely within a protein, since the vacuum dielectric constant (vacuum = 1) is more similar to the immediate environment of the interior of a protein (protein = 2-4) than for bulk water (water = 80).…”