Ultrafast Excited-State Dynamics of Kynurenine, a UV Filter of the Human Eye

Sherin, Peter S.; Grilj, Jakob; Tsentalovich, Yuri P.; Vauthey, Eric

doi:10.1021/jp900541b

Cited by 68 publications

(97 citation statements)

References 71 publications

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“…27,28 It has also been demonstrated that the chemical denaturation of the protein allows more bulk type water in the protein cavity, revealing faster time constants in the solvation dynamics. 27,28 A systematic study on the spectroscopy and dynamics of kynurenine in different solvents has been presented by Vauthey et al 16 The usefulness of the probe (kynurenine) as a solvation reporter has also been established. 16 The main excited-state deactivation channel of the probe depends on the interaction of the solvent molecules through hydrogen-bonding ability.…”

Section: Resultsmentioning

confidence: 99%

Toward an Alternative Intrinsic Probe for Spectroscopic Characterization of a Protein

2010

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The intrinsic fluorescent amino acid tryptophan is the unanimous choice for the spectroscopic investigation of proteins. However, several complicacies in the interpretation of tryptophan fluorescence in a protein are inevitable and an alternative intrinsic protein probe is a longstanding demand. In this contribution, we report an electron-transfer reaction in a human transporter protein (HSA) cavity which causes the tryptophan residue (Trp214) to undergo chemical modification to form one of its metabolites kynurenine (Kyn214). Structural integrity upon modification of the native protein is confirmed by dynamic light scattering (DLS) as well as near and far circular dichroism (CD) spectroscopy. Femtosecond-resolved fluorescence transients of the modified protein describe the dynamics of solvent molecules in the protein cavity in both the native and denatured states. In order to establish general use of the probe, we have studied the dipolar interaction of Kyn214 with a surface-bound ligand (crystal violet, CV) of the protein. By using the sensitivity of FRET, we have determined the distance between Kyn214 (donor) and CV (acceptor). Our study is an attempt to explore an alternative intrinsic fluorescence probe for the spectroscopic investigation of a protein. In order to establish the efficacy of the modification technique we have converted the tryptophan residues of other proteins (bovine serum albumin, chymotrypsin and subtilisin Carlsberg) to kynurenine and confirmed their structural integrity. We have also shown that catalytic activity of the enzymes remains intact upon the modification.

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Section: Resultsmentioning

confidence: 99%

Toward an Alternative Intrinsic Probe for Spectroscopic Characterization of a Protein

2010

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“…The early excited-state dynamics of KNY is similar to that of KN. 1 It has been shown that excitation of KN and other UV filters results in a charge transfer from the amino to the carbonyl group; 35 very likely that the same charge transfer occurs during the KNY excitation, which is supported by a large Stokes shift of the fluorescence band relative to the absorption spectrum (Fig. 1).…”

Section: Photophysics and Photochemistry Of Knymentioning

confidence: 93%

“…Most likely, the IC mechanism of KNY is similar to that of KN and other UV filters, and includes transformation of the absorbed light energy into heat via hydrogen bond vibrations. 1,2,35 Photolysis of KNY in aqueous solution results in the formation of two intermediates, observed by nanosecond flashphotolysis, namely the KNY triplet state and the species which was attributed to the KNY enol form in the ground state, and of two products detected in the irradiated samples by HPLC, i.e. 4HQN and DHQN.…”

Section: Photophysics and Photochemistry Of Knymentioning

confidence: 99%

“…The main deactivation pathway of the photoexcited UV filter in aqueous solutions is solvent-assisted internal conversion to the ground state, which proceeds with an efficiency of about 99%. 1,2 The "primary" UV filters, namely kynurenine (KN), 3-hydroxykynurenine (3OHKN) and 3-hydroxykynurenine O-β-D-glucoside (3OHKG), are synthesized enzymatically from tryptophan. [3][4][5][6] Under physiological conditions, these compounds can undergo spontaneous deamination 7,8 yielding highly reactive carboxyketoalkenes (CKAs), the subsequent reactions of the latter resulting in the production of "secondary" UV filters, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Photochemistry of aqueous solutions of kynurenic acid and kynurenine yellow

Zelentsova

Sherin

Snytnikova

et al. 2013

Photochem Photobiol Sci

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The photophysics and photochemistry of kynurenic acid (KNA) and kynurenine yellow (KNY) in neutral aqueous solutions were investigated using time-resolved optical spectroscopy. Both molecules have similar quinoline-like structures, the only difference being the absence of conjugation in the nitrogen containing cycle in KNY. The main channel of S 1 excited state decay in the case of partially-unconjugated KNY is the solvent assisted S 1 → S 0 radiationless transition via intermolecular hydrogen bonds (Φ IC = 0.96), whereas, in the case of fully-conjugated KNA, it is intersystem crossing to the triplet state (Φ T = 0.82). The major intermediate products of the singlet excited KNY deactivation are the triplet state (Φ T = 0.022) and, most probably, the enol form (Φ enol = 0.012), which decay with the formation of 2,3-dihydro-4-hydroxyquinoline and 4-hydroxyquinoline, respectively. The results obtained show that KNA and KNY, which are products of the decomposition of the UV filter kynurenine, are significantly more photoactive and less photostable than the parent molecule.

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“…13,[32][33][34][35][36][37][38][39] This process is enabled by the nitro groups of EB that are good hydrogen-bond acceptors. [24][25][26]40,41 In order to further confirm this hypothesis, TA measurements were carried out in perdeuterated water.…”

Section: Articlementioning

confidence: 99%

Ultrafast Excited-State Dynamics of Eosin B: A Potential Probe of the Hydrogen-Bonding Properties of the Environment

2011

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The photophysics of two dyes from the xanthene family, eosin B (EB), and eosin Y (EY) has been investigated in various solvents by femtosecond transient absorption spectroscopy, first, to clarify the huge disparity of the EB fluorescence lifetimes reported in literature, and, second, to understand the mechanism responsible for the ultrafast excited-state deactivation of EB in water. The excited-state lifetime of EB was found to be much shorter in water and in other protic solvents, due to the occurrence of hydrogen-bond assisted nonradiative deactivation. This mechanism is associated with the hydrogen bonds between the solvent molecules and the nitro groups of EB, which become stronger upon optical excitation due to the charge-transfer character of the excited-state. This process is not operative with EY, where the nitro groups are replaced by bromine atoms. Therefore, the excited-state lifetime of EB in solution is directly related to the strength of the solvent as a hydrogen-bond donor, offering the possibility to build a corresponding scale based on the fluorescence quantum yield or lifetime of EB. This scale of hydrogen-bonding strength could be especially useful for studies of liquid interfaces by time-resolved surface second harmonic generation

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Ultrafast Excited-State Dynamics of Kynurenine, a UV Filter of the Human Eye

Cited by 68 publications

References 71 publications

Toward an Alternative Intrinsic Probe for Spectroscopic Characterization of a Protein

Toward an Alternative Intrinsic Probe for Spectroscopic Characterization of a Protein

Photochemistry of aqueous solutions of kynurenic acid and kynurenine yellow

Ultrafast Excited-State Dynamics of Eosin B: A Potential Probe of the Hydrogen-Bonding Properties of the Environment

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