On the origin of nonexponential fluorescence decay in tryptophan and its derivatives

Petrich, Jacob W.; Chang, Mu‐Chieh; McDonald, Daniel B.; Fleming, Graham R.

doi:10.1021/ja00350a014

Cited by 335 publications

(286 citation statements)

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“…R 0 (in nm), the critical transfer distance, is defined as the donoracceptor distance at which the transfer efficiency is 50%. 2 is the orientation factor, n is the refractive index of the medium (Ϸ1.4), D and Q D are the donor excited-state lifetime and quantum yield in the absence of the acceptor (here in apoprotein), respectively, and J is the spectral overlap integral (in unit of cm 3 ͞M) between donor-emission and acceptor-absorption.…”

Section: Resultsmentioning

confidence: 99%

“…However, Trp fluorescence is complex because of different rotamers in the ground state and the two nearly degenerate electronic states ( 1 L a , 1 L b ) with perpendicular transition moments. Accordingly, numerous studies (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) have focused on the lifetime, quantum yield, Stokes shift, and fluorescence anisotropy. Most of these studies were made with picosecond or nanosecond time resolution (3,(6)(7)(8)(9)(10).…”

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confidence: 99%

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Femtosecond dynamics of rubredoxin: Tryptophan solvation and resonance energy transfer in the protein

Zhong

Pal

Zhang

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

138

134

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We report here studies of tryptophan (Trp) solvation dynamics in water and in the Pyrococcus furiosus rubredoxin protein, including the native and its apo and denatured forms. We also report results on energy transfer from Trp to the iron-sulfur [Fe-S] cluster. Trp fluorescence decay with the onset of solvation dynamics of the chromophore in water was observed with femtosecond resolution (Ϸ160 fs; 65% component), but the emission extended to the picosecond range (1.1 ps; 35% component). In contrast, the decay is much slower in the native rubredoxin; the Trp fluorescence decay extends to 10 ps and longer, reflecting the local rigidity imposed by residues and by the surface water layer. The dynamics of resonance energy transfer from the two Trps to the [Fe-S] cluster in the protein was observed to follow a temporal behavior characterized by a single exponential (15-20 ps) decay. This unusual observation in a protein indicates that the resonance transfer is to an acceptor of a well-defined orientation and separation. From studies of the mutant protein, we show that the two Trp residues have similar energy-transfer rates. The critical distance for transfer (R 0) was determined, by using the known x-ray data, to be 19.5 Å for Trp-36 and 25.2 Å for Trp-3, respectively. The orientation factor ( 2 ) was deduced to be 0.13 for Trp-36, clearly indicating that molecular orientation of chromophores in the protein cannot be isotropic with 2 value of 2͞3. These studies of solvation and energy-transfer dynamics, and of the rotational anisotropy, of the wild-type protein, the (W3Y, I23V, L32I) mutant, and the fmetPfRd variant at various pH values reveal a dynamically rigid protein structure, which is probably related to the hyperthermophilicity of the protein.T ryptophan (Trp) is the most important fluorophore among amino acid residues for optical probing of proteins. However, Trp fluorescence is complex because of different rotamers in the ground state and the two nearly degenerate electronic states ( 1 L a , 1 L b ) with perpendicular transition moments. Accordingly, numerous studies (1-10) have focused on the lifetime, quantum yield, Stokes shift, and fluorescence anisotropy. Most of these studies were made with picosecond or nanosecond time resolution (3, 6-10). To probe the local protein dynamics, Trp solvation by neighboring soft͞rigid water molecules, or by other polar amino acid residues, must be resolved on the femtosecond time scale. Moreover, such studies are important for examining the nature of resonance energy transfer (RET) that is used for deducing distances and orientations between the Trp and quenchers in the protein (e.g., see refs. 3 and 10, and references therein).We choose the hyperthermophilic iron-sulfur protein, Pyrococcus furiosus rubredoxin (PfRd), as a prototype system (Fig. 1). The high-resolution x-ray crystallographic structures of PfRd at 0.95 Å and its formylmethionine variant (fmetPfRd) at 1.2 Å, have been recently reported (11). PfRd is a small protein of 53 amino acid residues with an iron a...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Femtosecond dynamics of rubredoxin: Tryptophan solvation and resonance energy transfer in the protein

Zhong

Pal

Zhang

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

138

134

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“…Actually, the Trp fluorescence is known to be very complex, with strongly wavelength dependent decay times. 36 This has been assigned to the co-existence of several rotamers with different excited state dynamics, 47 which may also occur in the dyads. 40 The TCSPC profiles at 450 nm ( Figure 2B) were much slower than those at either 310 or 340 nm.…”

Section: Studies On Fbp/hsa Complexesmentioning

confidence: 99%

Excited state interactions between flurbiprofen and tryptophan in drug–protein complexes and in model dyads. Fluorescence studies from the femtosecond to the nanosecond time domains

Vayá

Bonancía

Jiménez

et al. 2013

Phys. Chem. Chem. Phys.

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We report here on the interaction dynamics between flurbiprofen (FBP) and tryptophan (Trp) covalently linked in model dyads and in a complex of FBP with human serum albumin (HSA) probed by time-10 resolved fluorescence spectroscopy from the femto-to the nano-second timescales. In the dyads, a rapid (k > 10 10 s -1 ) dynamic quenching of the 1 FBP* fluorescence is followed by a slower (k > 10 9 s -1 ) quenching of the remaining 1 Trp* fluorescence. Both processes display a clear stereoselectivity; the rates are 2-3 times higher for the (R,S)-dyad. In addition, a red-shifted exciplex emission is observed, rising in 100-200 ps. A similar two-step dynamic fluorescence quenching is also observed in the FBP/HSA 15 complex, although the kinetics of the involved processes are slower. The characteristic reorientational times determined for the two enantiomeric forms of FBP in the protein show that the interaction is stronger for the (R)-form. This is, to our knowledge, the first observation of stereo-selective flurbiprofentryptophan interaction dynamics with femtosecond time resolution.

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“…L-Tryptophan has been used as a fluorescence probe to monitor protein conformation and dynamics and consequently many spectroscopic studies of the electronic properties of L-tryptophan and its derivatives have been performed [14,15]. L-Tryptophan exhibits a non-exponential fluorescence decay in aqueous solutions and that has been explained by the emission from non-interconverting rotamers which have different lifetimes due to different rates of intramolecular charge transfer [16].…”

Section: Introductionmentioning

confidence: 99%

Crystal structure and properties of l-tryptophanium hydrogen selenite

Paixão¹,

Silva²,

Beja³

et al. 2006

Polyhedron

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L-Tryptophanium hydrogen selenite was synthesised and structurally characterised at room and low temperature. The aminoacid is positively charged with the amine and carboxylic group protonated. It adopts a staggered conformation with the N1 gauche to C4 that is gauche to C1. The anion displays a pyramidal conformation with three different Se-O bond lengths, one characteristic of a double bond, another of a single bond and the third with an intermediate character. At room temperature there is a disordered hydrogen atom between the carboxylic group of the cation and the O atom of the anion with the intermediate Se-O bond length. At low temperature this hydrogen atom orders and attaches to the carboxylic group. This ordering is most likely related to the transition seen in DSC measurements occurring at À82.5°C.

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On the origin of nonexponential fluorescence decay in tryptophan and its derivatives

Cited by 335 publications

References 1 publication

Femtosecond dynamics of rubredoxin: Tryptophan solvation and resonance energy transfer in the protein

Femtosecond dynamics of rubredoxin: Tryptophan solvation and resonance energy transfer in the protein

Excited state interactions between flurbiprofen and tryptophan in drug–protein complexes and in model dyads. Fluorescence studies from the femtosecond to the nanosecond time domains

Crystal structure and properties of l-tryptophanium hydrogen selenite

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