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

2020 ◽  
Vol 142 (28) ◽  
pp. 12106-12118
Author(s):  
Brian Koronkiewicz ◽  
John Swierk ◽  
Kevin Regan ◽  
James M. Mayer
Keyword(s):  
Tyrosine Oxidation ◽  
Distance Dependence

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

2020 ◽  
Author(s):  
Brian Koronkiewicz ◽  
John R. Swierk ◽  
Kevin P. Regan ◽  
James Mayer
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Long Range ◽  
Rate Constants ◽  
High Energy ◽  
Transfer Distance ◽  
Tyrosine Oxidation ◽  
Donor And Acceptor ◽  
Distance Dependence ◽  
Biological Electron Transfer

We have explored the kinetic effect of increasing electron transfer distance in a biomimetic, proton coupled electron transfer system (PCET). Biological electron transfer is often simultaneous with proton transfer in order to avoid the high-energy, charged intermediates resulting from the stepwise transfer of protons and electrons. These concerted proton electron transfer (CPET) reactions are implicated in numerous biological electron transfer pathways. In many cases, proton transfer is coupled to long-range electron transfer. While many studies have shown that the rate of electron transfer is sensitive to the distance between the electron donor and acceptor, extensions to biological CPET reactions are sparse. The possibility of a unique electron transfer distance dependence for CPET reactions deserves further exploration, as this could have implications for how we understand biological electron transfer. We therefore explored the electron transfer distance dependence for the CPET oxidation of tyrosine in a model system. We prepared a series of metallopeptides with a tyrosine separated from a Ru(bpy)<sub>3</sub><sup>2+</sup> complex by an oligoproline bridge of increasing length. Rate constants for intramolecular tyrosine oxidation were measured using the flash-quench transient absorption technique in aqueous solutions. The rate constants for tyrosine oxidation decreased by 125-fold with three added prolines residues between tyrosine and the oxidant. By comparison, related intramolecular ET rate constants in very similar constructs were reported to decrease by 4-5 orders of magnitude over the same number of prolines. The observed shallow distance dependence for tyrosine oxidation is proposed to originate, at least in part, from the requirement for stronger oxidants, leading to a smaller hole transfer tunneling barrier height. The shallow distance dependence observed here and extensions to distance dependent CPET reactions have far-reaching implications for long-range charge transfers

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

2020 ◽  
Author(s):  
Brian Koronkiewicz ◽  
John R. Swierk ◽  
Kevin P. Regan ◽  
James Mayer
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Long Range ◽  
Rate Constants ◽  
High Energy ◽  
Transfer Distance ◽  
Tyrosine Oxidation ◽  
Donor And Acceptor ◽  
Distance Dependence ◽  
Biological Electron Transfer

We have explored the kinetic effect of increasing electron transfer distance in a biomimetic, proton coupled electron transfer system (PCET). Biological electron transfer is often simultaneous with proton transfer in order to avoid the high-energy, charged intermediates resulting from the stepwise transfer of protons and electrons. These concerted proton electron transfer (CPET) reactions are implicated in numerous biological electron transfer pathways. In many cases, proton transfer is coupled to long-range electron transfer. While many studies have shown that the rate of electron transfer is sensitive to the distance between the electron donor and acceptor, extensions to biological CPET reactions are sparse. The possibility of a unique electron transfer distance dependence for CPET reactions deserves further exploration, as this could have implications for how we understand biological electron transfer. We therefore explored the electron transfer distance dependence for the CPET oxidation of tyrosine in a model system. We prepared a series of metallopeptides with a tyrosine separated from a Ru(bpy)<sub>3</sub><sup>2+</sup> complex by an oligoproline bridge of increasing length. Rate constants for intramolecular tyrosine oxidation were measured using the flash-quench transient absorption technique in aqueous solutions. The rate constants for tyrosine oxidation decreased by 125-fold with three added prolines residues between tyrosine and the oxidant. By comparison, related intramolecular ET rate constants in very similar constructs were reported to decrease by 4-5 orders of magnitude over the same number of prolines. The observed shallow distance dependence for tyrosine oxidation is proposed to originate, at least in part, from the requirement for stronger oxidants, leading to a smaller hole transfer tunneling barrier height. The shallow distance dependence observed here and extensions to distance dependent CPET reactions have far-reaching implications for long-range charge transfers

Insights into the Distance Dependence of Electron Transfer through Conformationally Constrained Peptides

2020 ◽  
Vol 7 (5) ◽  
pp. 1225-1237
Author(s):  
Claudio Zuliani ◽  
Fernando Formaggio ◽  
Laura Scipionato ◽  
Claudio Toniolo ◽  
Sabrina Antonello ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Conformationally Constrained ◽  
Distance Dependence ◽  
Constrained Peptides

scholarly journals Reaction of tyrosine oxidation products with proteins of the lens

1968 ◽  
Vol 109 (2) ◽  
pp. 301-305 ◽  
Author(s):  
Antoinette Pirie
Keyword(s):  
Ascorbic Acid ◽  
Fluorescence Spectra ◽  
Ferrous Sulphate ◽  
Oxidation Products ◽  
Thiol Groups ◽  
Lens Proteins ◽  
Bovine Lens ◽  
Tyrosine Oxidation ◽  
Cataractous Lens

Oxidation of tyrosine in the presence of bovine lens proteins leads to the formation of brown or black melanoproteins. Both tyrosinase and the oxidizing system of ferrous sulphate–ascorbic acid–EDTA are effective. The fluorescence of the lens proteins is both altered and enhanced by the tyrosine-oxidizing systems. Their fluorescence spectra resemble those of urea-insoluble proteins of human cataractous lens and of 1,2-naphthaquinone–proteins of naphthalene cataract. The lens proteins lose their thiol groups and, in acid hydrolysates of treated β-and γ-crystallins, a substance has been detected chromatographically that behaves similarly to a compound formed when 3,4-dihydroxyphenylalanine (dopa) is oxidized by tyrosinase in the presence of cysteine. Analysis and behaviour of this substance from hydrolysates of lens proteins suggest that it is a compound of cysteine and dopa.

Electron transfer through RNA: Chemical probing of dual distance dependence

2011 ◽  
Vol 19 (22) ◽  
pp. 6881-6884 ◽  
Author(s):  
Tadao Takada ◽  
Yumiko Otsuka ◽  
Mitsunobu Nakamura ◽  
Kazushige Yamana
Keyword(s):  
Electron Transfer ◽  
Chemical Probing ◽  
Dual Distance ◽  
Distance Dependence

Distance Dependence of Neuronal Growth on Nanopatterned Gold Surfaces

Langmuir ◽  
2011 ◽  
Vol 27 (1) ◽  
pp. 233-239 ◽  
Author(s):  
Cristian Staii ◽  
Chris Viesselmann ◽  
Jason Ballweg ◽  
Justin C. Williams ◽  
Erik W. Dent ◽  
...  
Keyword(s):  
Neuronal Growth ◽  
Gold Surfaces ◽  
Distance Dependence
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