Effects of external heavy atoms and other factors on the room-temperature phosphorescence and fluorescence of tryptophan and tyrosine

Meyers, Martin L.; Seybold, Paul G.

doi:10.1021/ac50047a006

Cited by 41 publications

(13 citation statements)

References 44 publications

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“…The obtained values for tryptophan and indole are not consistent with the literature data reported previously by Meyers and Seybold [22]. According to these authors, the Stern-Volmer constant for quenching of L-tryptophan (10 À5 M) in water (k ex = 296 nm, k em = 354 nm) by sodium iodide is equal to 18.9 M À1 ; and the value of 40.4 M À1 has been reported by them for NaJ quenching of aqueous indole (10 À5 M) (k ex = 279 nm, k em = 344 nm).…”

Section: Heavy Atom Effectcontrasting

confidence: 97%

“…However, the above mentioned Stern-Volmer constants (reported by Meyers and Seybold [22]) were determined using the steady state fluorescence measurements (from the ratio F 0 F ). The data concerning the fluorescence lifetimes of aqueous indole and tryptophan were not reported by these authors.…”

Section: Heavy Atom Effectmentioning

confidence: 99%

“…It may be postulated [22] that the charged COO À group of tryptophan keeps I À ions away from the vicinity of the a carbon and at the same time moves these ions toward the indole ring chromophore, which may lead to more effective quenching.…”

Section: Heavy Atom Effectmentioning

confidence: 99%

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Photophysics of indole, tryptophan and N-acetyl-l-tryptophanamide (NATA): Heavy atom effect

Kowalska-Baron

Chan

Gałęcki

et al. 2012

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Section: Heavy Atom Effectcontrasting

confidence: 97%

Section: Heavy Atom Effectmentioning

confidence: 99%

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Photophysics of indole, tryptophan and N-acetyl-l-tryptophanamide (NATA): Heavy atom effect

Kowalska-Baron

Chan

Gałęcki

et al. 2012

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…Iodide, bromide and alkyl halides are well established as heavy-atom perturbers of luminescence of aromatic and heteroaromatic fluorophores [28,[49][50][51][52][53][54] including indole [49,50] and tryptophan [49]. The presence of heavy atoms or heavy atom containing molecules in the environment increases the rates of spin-forbidden processes of the fluorophores via a spin-orbital coupling mechanism.…”

Section: Mechanisms Of Tryptophan Fluorescence Quenchingmentioning

confidence: 99%

Time-resolved and steady-state fluorescence quenching of N-acetyl-l-tryptophanamide by acrylamide and iodide

Zelent

Kuśba

Gryczyński

et al. 1998

Biophysical Chemistry

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We examined the time-resolved and steady-state fluorescence quenching of N-acetyl-L-tryptophanamide (NATA) by acrylamide and iodide, over a range of viscosities in propylene glycol. The quenching of NATA by acrylamide and iodide results in heterogeneity of the intensity decay which increases with the quencher concentration. We attribute the complex decays of NATA to transient effects in diffusion and the nature of the fluorophore-quencher interaction. These data were compared using the phenomenological radiation boundary condition (RBC) and distance-dependent quenching (DDQ) models for collisional quenching. We used global analysis of the time-resolved frequency-domain and steady-state data to select between the models. Consideration of both the frequency-domain and steady state data demonstrate that the quenching rate depends exponentially on the fluorophore-quencher distance, indicating the validity of the DDQ model. The rate constants for acrylamide and iodide quenching, at the constant distance of 5 A, were found to be near 10(13) s-1 and 10(9) s-1, respectively. These rates reflect electron transfer and exchange interactions as the probable quenching mechanisms, respectively.

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“…Since chlorin e 6 contains no heavy atoms that would be potentially capable of inducing quenching of tryptophan fluorescence [39], the most likely reason for the decrease in the quantum yield of the fluorescence of MDH in formation of complexes with chlorin is the photoinduced reversible transfer of an electron between interacting components. It seems that the role of the donor of the electron in this pair can be assigned to tryptophan (its ability to donate an electron upon photoexcitation is well known from the literature data [40]) and the role of the acceptor to chlorin e 6 .…”

mentioning

confidence: 99%

Spectral-luminescent properties of chlorin e 6 and malate dehydrogenase complexes

et al. 2004

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Spectral confirmation of the formation of stable equilibrium complexes (association constant K as = 2⋅10 6 M −1 ) of the Krebs cycle enzyme -malate dehydrogenase (MDH) -and one of the promising photodynamic sensitizers -chlorin e 6 -have been obtained. It is shown that the incorporation of dye molecules into the protein globule of dimeric MDH (each subunit of which contains 4 tryptophan amino acid residues, each binding one molecule of chlorin e 6 ) is accompanied by quenching of the tryptophan fluorescence of the enzyme. However, despite the overlapping of the fluorescence spectra of tryptophanyls of MDH and the absorption spectrum of chlorin e 6 , the fluorescence quenching observed is not caused by singlet-singlet inductive-resonant transfer of energy from the donor to the acceptor. The conclusion has been drawn that the reason for the absence of energy transfer from tryptophanyls to the dye is the more effective intertryptophan migration of energy to one of the most "longwave" amino acid residues, the quenching of the luminescence of which occurs due to the reversible photoinduced transfer of an electron to chlorin e 6 (formation of a complex with charge transfer). The formation of a complex with charge transfer between chlorin e 6 (when it is excited) and one of the amino acid residues of the enzyme that contact with the dye at its binding site on the protein molecule is also the most noncontradictory explanation of the observed (when bound with MDH) decrease in the quantum yield of fluorescence of chlorin e 6 upon increase in the duration of its quenching. The question of the ability of MDH to act as one of the most sensitive targets responsible for the disturbance of mitochondrial functions and initiation of the apoptosis of tumor cells in the process of photodynamic therapy is discussed.

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Effects of external heavy atoms and other factors on the room-temperature phosphorescence and fluorescence of tryptophan and tyrosine

Cited by 41 publications

References 44 publications

Photophysics of indole, tryptophan and N-acetyl-l-tryptophanamide (NATA): Heavy atom effect

Photophysics of indole, tryptophan and N-acetyl-l-tryptophanamide (NATA): Heavy atom effect

Time-resolved and steady-state fluorescence quenching of N-acetyl-l-tryptophanamide by acrylamide and iodide

Spectral-luminescent properties of chlorin e 6 and malate dehydrogenase complexes

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