On the influence of secondary structure on the α-C→H bond dissociation energy of proline residues in proteins: a theoretical study

Block, D.; Yu, Dake; Rauk, Arvi

doi:10.1139/v98-107

Cited by 11 publications

(18 citation statements)

References 2 publications

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“…Theoretical calculations predicted that thiyl radicals should react with α C-H bonds of most amino acids in proteins when located in flexible or β-sheet structures but not in α-helices[24–27]. Our kinetic NMR experiments confirmed that inter molecular hydrogen atom transfer (HAT) reactions of the general type displayed in Scheme 1, equilibrium 2, occur between thiyl radicals and several amino acids[28].…”

Section: Introductionsupporting

confidence: 58%

Protein thiyl radical reactions and product formation: a kinetic simulation

Nauser

Koppenol

Schöneich

2015

Free Radical Biology and Medicine

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Protein thiyl radicals are important intermediates generated in redox processes of thiols and disulfides. Thiyl radicals efficiently react with glutathione and ascorbate, and the common notion is that these reactions serve to eliminate thiyl radicals before they can enter potentially hazardous processes. However, over the past years increasing evidence has been provided for rather efficient intramolecular hydrogen transfer processes of thiyl radicals in proteins and peptides. Based on rate constants published for these processes, we have performed kinetic simulations of protein thiyl radical reactivity. Our simulations suggest that protein thiyl radicals enter intramolecular hydrogen transfer reactions to a significant extent even under physiologic conditions, i.e. in the presence of 30 μM oxygen, 1 mM ascorbate and 10 mM glutathione. At lower concentrations of ascorbate and glutathione, frequently observed when tissue is exposed to oxidative stress, the extent of irreversible protein thiyl radical-dependent protein modification increases.

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Section: Introductionsupporting

confidence: 58%

Protein thiyl radical reactions and product formation: a kinetic simulation

Nauser

Koppenol

Schöneich

2015

Free Radical Biology and Medicine

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“…Experimentally-determined values are shown in bold; calculated values are shown in italics. b Hydrogen-atom abstraction reaction efficiency = second-order hydrogen-atom abstraction rate constant/collision rate constant (k exp /k coll ). c Reference 71. d Reference 61. e Reference 53. f Reference 72. g Reference 62. h Reference 22. i Reference 74. j Average of the BDE values for cis- and trans- proline; reference 75. k Reference 73. …”

Section: Figures and Tablesmentioning

confidence: 99%

Correlation of Hydrogen-Atom Abstraction Reaction Efficiencies for Aryl Radicals with their Vertical Electron Affinities and the Vertical Ionization Energies of the Hydrogen-Atom Donors

2008

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The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer (FT – ICR). Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropanol, were measured for twenty-three structurally different, positively-charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for three of the aryl radicals with isopropanol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of several different hydrogen-atom donors with a few selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X – H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of twenty-nine different aryl radicals and eighteen different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state as the energy difference between the neutral and ionic reactants decreases. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be “tuned” by structural changes that influence either the vertical EA of the aryl radical or the vertical IE of the hydrogen atom donor.

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“…via “long range hydrogen transfer” (based on the position of amino acids within the protein sequence) (reaction 8). Theoretical calculations by Rauk and co-workers show that thiyl radicals should react with α C-H bonds of protein amino acids when located in flexible or β-sheet structures but not within α-helices [79–82]. …”

Section: Hydrogen Transfer Reactions Of Thiyl Radicalsmentioning

confidence: 99%

Thiyl radicals and induction of protein degradation

Schöneich

2015

Free Radical Research

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Thiyl radicals are important intermediates in the redox biology and chemistry of thiols. These radicals can react via hydrogen transfer with various C-H bonds in peptides and proteins, leading to the generation of carbon-centered radicals, and, potentially, to irreversible protein damage. This review summarizes quantitative information on reaction kinetics and product formation, and discusses the significance of these reactions for protein degradation induced by thiyl radical formation.

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On the influence of secondary structure on the α-C→H bond dissociation energy of proline residues in proteins: a theoretical study

Cited by 11 publications

References 2 publications

Protein thiyl radical reactions and product formation: a kinetic simulation

Protein thiyl radical reactions and product formation: a kinetic simulation

Correlation of Hydrogen-Atom Abstraction Reaction Efficiencies for Aryl Radicals with their Vertical Electron Affinities and the Vertical Ionization Energies of the Hydrogen-Atom Donors

Thiyl radicals and induction of protein degradation

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