Shallow Distance Dependence for Proton-Coupled Tyrosine Oxidation in Oligoproline Peptides

Koronkiewicz, Brian; Swierk, John R.; Regan, Kevin P.; Mayer, James M.

doi:10.1021/jacs.0c01429

Cited by 12 publications

(12 citation statements)

References 106 publications

(289 reference statements)

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“…The relatively flat curve for ln[ k PCET ( R ET )] versus R ET in Figure C at small R ET predicts similar rate constants for the PCET systems with no proline linkage and with a single proline linkage, assuming the same value for V el 0 . This behavior is consistent with experimental data indicating that the PCET system without a proline linkage has a rate constant of 3 × 10 6 M –1 s –1 , which is similar to the rate constant of 1.4 × 10 6 M –1 s –1 measured experimentally for the PCET system with one proline linkage. As mentioned in the Introduction, only a few studies of the dependence of the PCET rate constant on the ET distance have been reported. ,, In the study of PCET in iron carboxytetraphenylporphyrin complexes, a relatively small slope magnitude of 0.23 Å –1 for the distance dependence of the rate constant was measured, compared to the value of 0.4–0.46 Å –1 measured for ET reactions with the same bridge unit. , In this system, the PCET reaction has an electrostatic term with Δ( Q Ru Q PA ) = e 2 , while each ET reaction has an electrostatic term with Δ( Q Ru Q PA ) = − e 2 or zero.…”

Section: Resultssupporting

confidence: 91%

“…Impact of Coupling Attenuation Parameter. Previous work 50 suggested that the coupling attenuation parameter β ET may be different for the ET and PCET systems, based on the different donor−bridge−acceptor energetics. To investigate this possibility, we repeated our calculations with β ET = 1.2 Å −1 rather than 1.4 Å −1 for the PCET systems.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“… a The calculated (experimental) magnitudes of the slopes are obtained from the calculated (experimental) ln( k ) versus the calculated R̅ ET values from Table . b Value for ET in Ru/Ru system (Figure A) determined by plotting the experimental rate constants from ref as a function of the calculated R̅ ET values. c Value from ref . d Value for Ru/Tyr system (Figure B) with hydrogen phosphate as proton acceptor determined by plotting the experimental rate constants from ref as a function of the calculated R̅ ET values. e Value from ref . f Value for Ru/Tyr system with imidazole as proton acceptor determined by plotting the experimental rate constants measured herein as a function of the calculated R̅ ET values. …”

Section: Resultsmentioning

confidence: 99%

“… d Value for Ru/Tyr system (Figure B) with hydrogen phosphate as proton acceptor determined by plotting the experimental rate constants from ref as a function of the calculated R̅ ET values. …”

Section: Resultsmentioning

confidence: 99%

“…Recently, a series of oligoproline peptides connecting Ru(bpy) 3 2+ and tyrosine was designed and studied experimentally with a flash-quench transient absorption method . In these experiments, photogenerated Ru(bpy) 3 3+ oxidized tyrosine by a concerted PCET process involving intramolecular ET from tyrosine to Ru(bpy) 3 3+ and proton transfer from tyrosine to the hydrogen phosphate buffer in aqueous solution (Figure ).…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of Shallow Distance Dependence of Proton-Coupled Electron Transfer in Oligoproline Peptides

Soudackov

Koronkiewicz

et al. 2020

J. Am. Chem. Soc.

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Long-range electron transfer is coupled to proton transfer in a wide range of chemically and biologically important processes. Recently the proton-coupled electron transfer (PCET) rate constants for a series of biomimetic oligoproline peptides linking Ru(bpy)3 2+ to tyrosine were shown to exhibit a substantially shallower dependence on the number of proline spacers compared to the analogous electron transfer (ET) systems. The experiments implicated a concerted PCET mechanism involving intramolecular electron transfer from tyrosine to Ru(bpy)3 3+ and proton transfer from tyrosine to a hydrogen phosphate dianion. Herein these PCET systems, as well as the analogous ET systems, are studied with microsecond molecular dynamics, and the ET and PCET rate constants are calculated with the corresponding nonadiabatic theories. The molecular dynamics simulations illustrate that smaller ET donor−acceptor distances are sampled by the PCET systems than by the analogous ET systems. The shallower dependence of the PCET rate constant on the ET donor–acceptor distance is explained in terms of an additional positive, distance-dependent electrostatic term in the PCET driving force, which attenuates the rate constant at smaller distances. This electrostatic term depends on the change in the electrostatic interaction between the charges on each end of the bridge and can be modified by altering these charges. On the basis of these insights, this theory predicted a less shallow distance dependence of the PCET rate constant when imidazole rather than hydrogen phosphate serves as the proton acceptor, even though their pK a values are similar. This theoretical prediction was subsequently validated experimentally, illustrating that long-range electron transfer processes can be tuned by modifying the nature of the proton acceptor in concerted PCET processes. This level of control has broad implications for the design of more effective charge-transfer systems.

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Section: Resultssupporting

confidence: 91%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Theoretical Study of Shallow Distance Dependence of Proton-Coupled Electron Transfer in Oligoproline Peptides

Soudackov

Koronkiewicz

et al. 2020

J. Am. Chem. Soc.

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Single‐molecule Conductance and Electrochemical Measurements of Electron Transfer in β‐strand Peptides

Mo,

Horsley,

et al. 2023

ChemElectroChem

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A series of β‐strand peptides comprising redox‐active amino acids in the P2 position were synthesized to investigate the effects of electron‐rich side chains on charge transfer and possible coupling interactions between side chains. Electrochemical results indicated a direct link between aromaticity of the side chains and electron transfer rate constants, while single‐molecule conductance studies supported the ability of the electron‐rich side chains to behave as ‘stepping stones’ to facilitate electron transfer through the peptides. Additional electrochemical analysis of the analogue containing D‐Tyr in the P2 position was undertaken at various pH levels and revealed intramolecular coupling interaction between the side chains, providing further insights on proton coupled electron transfer (PCET). These findings progress the established fundamental knowledge of charge transfer kinetics and explore new pathways for advancement in the architecture of molecular‐based electronic components and devices.

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Profiling charge transport: A new computational approach

Maqboul

2023

International Journal of Biological Macromolecules

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Shallow Distance Dependence for Proton-Coupled Tyrosine Oxidation in Oligoproline Peptides

Cited by 12 publications

References 106 publications

Theoretical Study of Shallow Distance Dependence of Proton-Coupled Electron Transfer in Oligoproline Peptides

Theoretical Study of Shallow Distance Dependence of Proton-Coupled Electron Transfer in Oligoproline Peptides

Single‐molecule Conductance and Electrochemical Measurements of Electron Transfer in β‐strand Peptides

Profiling charge transport: A new computational approach

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