Photophysics of indole derivatives:  experimental resolution of La and Lb transitions and comparison with theory

Eftink, Maurice R.; Selvidge, LeRoy A.; Callis, Patrik R.; Rehms, Aden A.

doi:10.1021/j100372a022

Cited by 150 publications

(110 citation statements)

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“…8-12) and 303.9 nm, 38-40 respectively, our spectrum clearly contains significant hot-band contributions, as would be expected given the elevated temperature of the absorption cell used in our measurement. This much larger shift in the energetic position of the 1 L b state compared to 1 L a is consistent with our calculations (see Table I) and is also in agreement with experimental band decomposition studies carried out on the related 5-methoxyindole system in propylene glycol glass 49 and polyethylene films. 50 In Figure 5 the short wavelength feature below 220 nm in indole also appears to broaden and move to longer wavelengths in 5-hydroxyindole.…”

Section: B Uv Spectrasupporting

confidence: 92%

“…There have been several band decomposition studies in the UV absorption region that have been carried out on crystalline indole 60 as well as indole in propylene glycol glass 49,61,62 and polymer films. 63 On the basis of this data, we are confidently able to assume that, at 249 nm, we are exciting almost exclusively to the 1 L a state (even given the small shifts in the relative and absolute positions of the 1 L a and 1 L b states in these solid media relative to the gas phase).…”

Section: A Indole At 249 Nmmentioning

confidence: 99%

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Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy

Livingstone¹,

Schalk²,

Boguslavskiy³

et al. 2011

The Journal of Chemical Physics

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Time-resolved photoelectron spectroscopy was used to obtain new information about the dynamics of electronic relaxation in gas-phase indole and 5-hydroxyindole following UV excitation with femtosecond laser pulses centred at 249 nm and 273 nm. Our analysis of the data was supported by ab initio calculations at the coupled cluster and complete-active-space self-consistent-field levels. The optically bright 1 L a and 1 L b electronic states of 1 ππ* character and spectroscopically dark and dissociative 1 πσ* states were all found to play a role in the overall relaxation process. In both molecules we conclude that the initially excited 1 L a state decays non-adiabatically on a sub 100 fs timescale via two competing pathways, populating either the subsequently long-lived 1 L b state or the 1 πσ* state localised along the N-H coordinate, which exhibits a lifetime on the order of 1 ps. In the case of 5-hydroxyindole, we conclude that the 1 πσ* state localised along the O-H coordinate plays little or no role in the relaxation dynamics at the two excitation wavelengths studied.

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Section: B Uv Spectrasupporting

confidence: 92%

Section: A Indole At 249 Nmmentioning

confidence: 99%

Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy

Livingstone¹,

Schalk²,

Boguslavskiy³

et al. 2011

The Journal of Chemical Physics

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“…The anisotropy decay of 14-3-3w242 was found to be highly heterogenous. The anisotropies of all samples started to decay from the initial value of r 0 ϭ 0.23, which is consistent with an excitation anisotropy spectra of Trp excited at 298 nm (33). MEM analysis revealed two classes of short correlation times, one located near 200 ps and the other close to 1 ns (Fig.…”

Section: The Mobility Of Trp 242 Is Higher Upon Ligand Binding: Timersupporting

confidence: 84%

14-3-3ζ C-terminal Stretch Changes Its Conformation upon Ligand Binding and Phosphorylation at Thr232

Obšilová

Heřman

Večeř

et al. 2004

Journal of Biological Chemistry

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14-3-3 proteins are abundant binding proteins involved in many biologically important processes. 14-3-3 proteins bind to other proteins in a phosphorylation-dependent manner and function as scaffold molecules modulating the activity of their binding partners. In this work, we studied the conformational changes of 14-3-3 C-terminal stretch, a region implicated in playing a role in the regulation of 14-3-3. Time-resolved fluorescence and molecular dynamics were used to investigate structural changes of the C-terminal stretch induced by phosphopeptide binding and phosphorylation at Thr 232 , a casein kinase I phosphorylation site located within this region. A tryptophan residue placed at position 242 was exploited as an intrinsic fluorescence probe of the Cterminal stretch dynamics. Other tryptophan residues were mutated to phenylalanine. Time-resolved fluorescence measurements revealed that phosphopeptide binding changes the conformation and increases the flexibility of 14-3-3 C-terminal stretch, demonstrating that this region is directly involved in ligand binding. Phosphorylation of 14-3-3 at Thr 232 resulted in inhibition of phosphopeptide binding and suppression of 14-3-3-mediated enhancement of serotonin N-acetyltransferase activity. Time-resolved fluorescence of Trp 242 also revealed that phosphorylation at Thr 232 induces significant changes of the C-terminal stretch conformation. In addition, molecular dynamic simulations suggest that phosphorylation at Thr 232 induces a more extended conformation of 14-3-3 C-terminal stretch and changes its interaction with the rest of the 14-3-3 molecule. These results indicate that the conformation of the C-terminal stretch plays an important role in the regulation of 14-3-3 binding properties.

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“…(3) (shown in Figure 5). The values of the apparent rotational correlation times, calculated this way using a value of r 0 of 0.16, 46 are shown in Figure 5. There is a considerable increase in rotational correlation times of tryptophan residue(s) of melittin with increasing ionic strength, which clearly shows that the observed change in fluorescence polarization (Figure 4) is not due to any lifetime-induced artifacts.…”

Section: Figurementioning

confidence: 99%

Effect of ionic strength on folding and aggregation of the hemolytic peptide melittin in solution

Raghuraman

Chattopadhyay

2006

Biopolymers

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Melittin is a cationic, amphipathic, hemolytic peptide composed of 26 amino acid residues. It is intrinsically fluorescent due to the presence of a single tryptophan residue, which has been shown to be crucial for its hemolytic activity. It undergoes a structural transition from a random coil monomer to an alpha-helical tetramer at high ionic strength. Although the aggregation behavior of melittin in solution is well characterized, dynamic information associated with the aggregation of melittin is lacking. In this paper, we have monitored the effect of ionic strength on the dynamics and aggregation behavior of melittin in aqueous solution by utilizing sensitive fluorescence approaches, which include the red edge excitation shift (REES) approach. Importantly, we demonstrate that REES is sensitive to the self-association of melittin induced by ionic strength. The change in environment experienced by melittin tryptophan(s) is supported by changes in fluorescence emission maximum, polarization, and lifetime. In addition, the accessibility of the tryptophan residue was probed by fluorescence quenching experiments using acrylamide and trichloroethanol as soluble and hydrophobic quenchers, respectively. Circular dichroism studies confirm the ionic strength-induced change in the secondary structure of melittin. Taken together, these results constitute the first report showing that REES could be used as a sensitive tool to monitor the aggregation behavior of melittin in particular and other proteins and peptides in general.

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Photophysics of indole derivatives: experimental resolution of La and Lb transitions and comparison with theory

Cited by 150 publications

References 0 publications

Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy

Following the excited state relaxation dynamics of indole and 5-hydroxyindole using time-resolved photoelectron spectroscopy

14-3-3ζ C-terminal Stretch Changes Its Conformation upon Ligand Binding and Phosphorylation at Thr232

Effect of ionic strength on folding and aggregation of the hemolytic peptide melittin in solution

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