Laser Photolysis of 3‐methyllumiflavin

Abstract

Abstract—The pH dependence of the transient absorptions of 3‐methyllumiflavin has been investigated with laser photolysis in the nanosecond time range. Three different transient species (I, II and III) can be observed. The analysis of the decay curves shows that I and II can be ascribed to the optical absorption spectra of the lowest excited singlet and triplet states, respectively. Their appearance is not affected by a change of pH of the solution. The transient spectra due to species III have a decay which is dependent on pH. By comparison of these results with spectral data obtained with flavin dissolved in polymethylmethacrylate and with photochemical data reported in the literature, a structure for III is proposed which might explain the observed pH dependence.

Dynamics of Excited Flavoproteins—picosecond Laser Photolysis Studies

“…Ultrafast process of the formation of the C T complex between excited flavin and tryptophan takes place within 33 ps and the produced C T state decays in a few ns. It should be noted that the present work shows no indication of the production of long-lived species such as free radical of flavins (Massey and Palmer, 1966) or flavin triplet state (Visser et al, 1974) which shows absorption spectra in the 45G800-nm region. The formation of the CT complex in the relatively nonpolar environment of protein should be possible only when the isoalloxazine ring of FMN or Trp-60 possess motional freedom in picosecond time-scale.…”

Review - Flavins as photoreceptors of blue light and their spectroscopic properties

“…Meanwhile, only several authors performed relevant studies: Müller et al (1973) observed the temperature changes in absorption spectra due to flavins (and flavins derivatives) dimers. The existence of flavins dimers has also been proposed by Harders et al (1974), Visser et al ( 1974 and Heelis et al (1978). Song et al (1972) based on the phosphorescence excitation spectra at T=77 K suggested extremely weak fluorescence of riboflavin (and its derivative) dimer.…”

Resonance energy transfer between FMN molecules in the presence of dimers: A review

“…Until the eighties, the dimerization process of FMN and its influence on absorption spectra has not been studied, although the suggestions that flavins might form dimers had appeared earlier in literature [50,51,65]. Song et al [57] suggested extremely weak fluorescence of riboflavin (and its derivative) dimer based on the phosphorescence excitation spectra at T = 77 K. The mentioned studies have not been, however, oriented towards the determination of dimerization constant and investigation of dimerization process.…”

“…In water, the solubility of FMN reaches 8 × 10 −2 M, but in investigations of FMN in water the following range of concentrations was used: from C = 1 × 10 −5 M to 1.8 × 10 −2 M (in publications [62,64,35,68]). However, the solubility of FMN in the glycerol-water (GW) solution and in PVA is higher, so C max = [ [50][51][52] 9 × 10 −2 M was used for GW solution [64,69,70] and C max = 1 M for PVA [61,36].…”

“…Spectroscopy and photochemistry of flavins have been the subject of intensive studies for about eighty years [45][46][47][48][49][50][51][52][53][54][55][56][57][58] in view of the wide biological function that they play in living organisms, particularly as chromophores in blue light photoreceptors [1,6,14]. Since the sixties of the 20th century every few years the symposia devoted to flavins: "Flavins and Flavoproteins -International Symposium" have been organized.…”