Evidence for through-bond long-range electron transfer in peptides

DeFelippis, Michael R.; Faraggi, M.; Klapper, Michael H.

doi:10.1021/ja00170a039

Cited by 84 publications

(56 citation statements)

References 3 publications

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“…The significance of the more C-terminal position of oxidizable groups was also reported by Faraggi et al [5] and DeFelippis et al [6], using pulse radiolysis to compare the oxidation rates of peptides containing both Tyr and Trp residues. Faraggi et al [5] had observed a similar position-specific oxidation behavior using differential pulse polarography of Trp-Gly-Tyr vs. Tyr-Gly-Trp.…”

Section: Ty R Tyr-tyr [A]supporting

confidence: 55%

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The voltammetry of neuropeptides containing L‐tyrosine

1995

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Neuropeptides containing an N-terminal tyrosine are irreversibly oxidized on glassy carbon electrodes using scan rates from 0.020 to 0.500 Vjs. Despite variations in peptide length and amino acid composition from tyrosine to a-neoendorphin 1-10, peak potentials occurred in a relatively narrow range from +0.925 V to +0.971 V (vs. Ag/AgCl). An inverse linear relationship of Ep vs. pH with a slope near -59mV/pH unit suggests that the oxidation involves a one electron oxidation and a single proton transfer similar to the oxidation of simple para-substituted phenols. Linear slopes between 0.790 and 0.933 of logIp vs. logv suggest that surface processes contribute to the voltammetry on glassy carbon.

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Section: Ty R Tyr-tyr [A]supporting

confidence: 55%

“…Faraggi et al [5] had observed a similar position-specific oxidation behavior using differential pulse polarography of Trp-Gly-Tyr vs. Tyr-Gly-Trp. They suggested that the redox potential depended on the relative position of Tyr and Trp in the peptide sequence and was not specifically affected by the N and C-terminus [6].…”

Section: Ty R Tyr-tyr [A]mentioning

confidence: 99%

The voltammetry of neuropeptides containing L‐tyrosine

1995

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“…Although through-bond PET has been observed in polyprolines separating strong organic donors and acceptors (33)(34)(35)(36), any significant contribution in these experiments can be ruled out by the observation of Ϸ100% QY for the R6G-Trp conjugate (in which intramolecular complex formation is prevented by the short and stiff linker), the use of saturated alkyl chains as fluorophore linker, and the steep sigmoidal distance dependence observed for MR113-Trp conjugates.…”

Section: Steady-state Fluorescence Quenching Experiments Of Polyprolinementioning

confidence: 89%

Probing polyproline structure and dynamics by photoinduced electron transfer provides evidence for deviations from a regular polyproline type II helix

Doose

Neuweiler

Barsch

et al. 2007

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

117

142

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Polyprolines are well known for adopting a regular polyproline type II helix in aqueous solution, rendering them a popular standard as molecular ruler in structural molecular biology. However, single-molecule spectroscopy studies based on Fö rster resonance energy transfer (FRET) have revealed deviations of experimentally observed end-to-end distances of polyprolines from theoretical predictions, and it was proposed that the discrepancy resulted from dynamic flexibility of the polyproline helix. Here, we probe end-to-end distances and conformational dynamics of poly-Lprolines with 1-10 residues using fluorescence quenching by photoinduced-electron transfer (PET). A single fluorophore and a tryptophan residue, introduced at the termini of polyproline peptides, serve as sensitive probes for distance changes on the subnanometer length scale. Using a combination of ensemble fluorescence and fluorescence correlation spectroscopy, we demonstrate that polyproline samples exhibit static structural heterogeneity with subpopulations of distinct end-to-end distances that do not interconvert on time scales from nano-to milliseconds. By observing prolyl isomerization through changes in PET quenching interactions, we provide experimental evidence that the observed heterogeneity can be explained by interspersed cis isomers. Computer simulations elucidate the influence of trans/ cis isomerization on polyproline structures in terms of end-to-end distance and provide a structural justification for the experimentally observed effects. Our results demonstrate that structural heterogeneity inherent in polyprolines, which to date are commonly applied as a molecular ruler, disqualifies them as appropriate tool for an accurate determination of absolute distances at a molecular scale.fluorescence correlation spectroscopy ͉ molecular ruler ͉ prolyl isomerization ͉ biopolymer ͉ Förster resonance energy transfer F luorescence spectroscopy provides a variety of tools to measure distances, monitor dynamics, or observe molecular interactions with sensitivity far beyond that of other biophysical techniques. Distance-dependent interactions between fluorophores and fluorescence-quenching molecular compounds, such as Förster resonance energy transfer (FRET) or photoinduced electron transfer (PET), are capable of reporting on processes on the nanometer length scale, below the diffraction limit generally imposed on optical techniques. Although much information is gained from relative distances or distance changes, the quest for precise determination of absolute distances has been ongoing ever since Stryer and Haugland presented the application of FRET as a spectroscopic ruler (1). FRET is a nonradiative dipole-dipole interaction between two fluorophores (donor D and acceptor A) that can serve as a spectroscopic ruler on length scales between Ϸ2 and Ϸ10 nm (2-6). Structurally well defined model systems (molecular rulers) are needed for validation of spectroscopic rulers as much as the latter are essential for structural investigations. Since the sem...

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“…However, the bridge greatly influences the solvent reorganization energy, the ET matrix element, and consequently the rate constant. In the previous studies for intramolecular ET in rigid peptides, proline, which contains a five-membered rings, was chosen as the bridge by several laboratories 15,35,36 and the kinetic models for the proline mediated ET reactions were intensively investigated. [37][38][39][40] In our present study, we choose two model peptides (see Scheme 1) for our purpose.…”

Section: Resultsmentioning

confidence: 99%

Solvent Reorganization Energy of Intramolecular Electron Transfer in Peptides Involving Tryptophan and Tyrosine

Zhao

et al. 2008

Chin. J. Chem.

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Intramolecular electron transfer (ET) from tyrosine to tryptophan within peptide Trp-(Pro) n -Tyr (n＝1, 2) has been investigated by ab initio calculation associated with a proper consideration of solvent effect by a continuum model. After geometry optimizations of the charge-localized reactant and product, double-well potentials have been constructed by adopting the linear reaction coordinate. The transition state has been determined by finding the crossing point of the potential energy curves. The realistic ET reaction was found complicated in polar solvent, hence the solvent reorganization energy of the electron transfer has received especial attention in this work. Applying the nonequilibrium solvation procedure implemented based on the polarizable continuum model by the authors, the solvent reorganization energy was estimated to be 87.36 kJ/mol for the ET in Trp-Pro-Tyr system and 105.80 kJ/mol for Trp-(Pro) 2 -Tyr.

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Evidence for through-bond long-range electron transfer in peptides

Cited by 84 publications

References 3 publications

The voltammetry of neuropeptides containing L‐tyrosine

The voltammetry of neuropeptides containing L‐tyrosine

Probing polyproline structure and dynamics by photoinduced electron transfer provides evidence for deviations from a regular polyproline type II helix

Solvent Reorganization Energy of Intramolecular Electron Transfer in Peptides Involving Tryptophan and Tyrosine

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