Computational Characterization of Sulfur−Oxygen Three-Electron-Bonded Radicals in Methionine and Methionine-Containing Peptides:  Important Intermediates in One-Electron Oxidation Processes

Pogocki, Dariusz; Serdiuk, Katarzyna; Schöneich, Christian

doi:10.1021/jp034811b

Cited by 37 publications

(42 citation statements)

References 104 publications

(259 reference statements)

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“…However, the results agree with experimental data, which show that methionine is a poor reducing agent for copper in solution [21][22]. The positively charged sulfur has been suggested to be stabilized by its backbone carbonyl oxygen [23]. As can be seen in Fig.…”

Section: Met35 Radical Cation Formation Drives the Reduction Of Cu(ii)supporting

confidence: 89%

Generation of soluble oligomeric β-amyloid species via copper catalyzed oxidation with implications for Alzheimer’s disease: A DFT study

et al. 2009

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A mechanism for the oxidation of a dimeric β-amyloid copper ion complex is proposed based on DFT calculations. It involves the Met35 residue, which is believed to be important in the neurotoxicity causing Alzheimer's disease. Oxidation of Met35 is found to proceed readily with dioxygen when two Met35 residues are close to each other and the copper ion. This indicates that oxidants, such as hydrogen peroxide, are not necessary for oxidation of β-amyloid copper ion complexes. Understanding these processes could be pivotal in gaining more knowledge of this complex disease and for the development of therapeutic treatments.Response to Reviewers: We are happy with the favorable comments by the reviewer. A short summary has been added to the manuscript as suggested by the reviewer. AbstractA mechanism for the oxidation of a dimeric -amyloid copper ion complex is proposed based on DFT calculations. It involves the Met35 residue, which is believed to be important in the neurotoxicity causing Alzheimer's disease. Oxidation of Met35 is found to proceed readily with dioxygen when two Met35 residues are close to each other and the copper ion. This indicates that oxidants, such as hydrogen peroxide, are not necessary for oxidation of -amyloid copper ion complexes. Understanding these processes could be pivotal in gaining more knowledge of this complex disease and for the development of therapeutic treatments.

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Section: Met35 Radical Cation Formation Drives the Reduction Of Cu(ii)supporting

confidence: 89%

Generation of soluble oligomeric β-amyloid species via copper catalyzed oxidation with implications for Alzheimer’s disease: A DFT study

et al. 2009

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“…This may reflect the fact that this PT reaction is coupled to longrange ET from Met108. Furthermore, at the Met108 site the ET would need to be coupled to a water (and subsequent deprotonation) or hydroxide attack to stabilize the resulting methionine cation radical (41)(42)(43). It is interesting to note that Geng et al (6) previously used ET theory (44) to analyze the temperature dependence of the rate of disappearance of the 950-nm absorbance during the decay of the bis-Fe IV state.…”

Section: Tsmentioning

confidence: 99%

Roles of multiple-proton transfer pathways and proton-coupled electron transfer in the reactivity of the bis -Fe ^IV state of MauG

Williamson

Davidson

2015

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

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The high-valent state of the diheme enzyme MauG exhibits charge–resonance (CR) stabilization in which the major species is a bis-FeIV state with one heme present as FeIV=O and the other as FeIV with axial heme ligands provided by His and Tyr side chains. In the absence of its substrate, the high-valent state is relatively stable and returns to the diferric state over several minutes. It is shown that this process occurs in two phases. The first phase is redistribution of the resonance species that support the CR. The second phase is the loss of CR and reduction to the diferric state. Thermodynamic analysis revealed that the rates of the two phases exhibited different temperature dependencies and activation energies of 8.9 and 19.6 kcal/mol. The two phases exhibited kinetic solvent isotope effects of 2.5 and 2.3. Proton inventory plots of each reaction phase exhibited extreme curvature that could not be fit to models for one- or multiple-proton transfers in the transition state. Each did fit well to a model for two alternative pathways for proton transfer, each involving multiple protons. In each case the experimentally determined fractionation factors were consistent with one of the pathways involving tunneling. The percent of the reaction that involved the tunneling pathway differed for the two reaction phases. Using the crystal structure of MauG it was possible to propose proton–transfer pathways consistent with the experimental data using water molecules and amino acid side chains in the distal pocket of the high-spin heme.

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“…aminoacids, peptides, proteins) has been the subject of many investigations due to its role in medicine, biology and basic chemistry [1,2]. One of the sites likely attacked by oxidative T agents is a sulfur atom in methionine residues [3][4][5]. The methionine residue in some biological systems can be attacked by oxidative species causing oxidative stress and biological aging [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…One of the sites likely attacked by oxidative T agents is a sulfur atom in methionine residues [3][4][5]. The methionine residue in some biological systems can be attacked by oxidative species causing oxidative stress and biological aging [1][2][3][4][5]. There are numerous studies on the possible stabilization of the sulfide radical cation ([S d? )…”

Section: Introductionmentioning

confidence: 99%

“…There are numerous studies on the possible stabilization of the sulfide radical cation ([S d? ) through intramolecular complexation with nucleophilic sites present in the neighboring groups, and donating electron lone pairs necessary to form a two-centered three-electron 2r/1r* bond [3][4][5]. Direct one-electron oxidation of methionine-containing compounds is possible, e.g., by using 4-carboxybenzophenone (CB) [6] or benzophenone (BP) [7][8][9] as the triplet sensitizers in aqueous or organic solvents, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Photosensitized oxidation of methionine derivatives. Laser flash photolysis studies

2009

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The early events in the triplet 4-carboxybenzophenone (CB)-induced oxidation of N-acetyl-methionine methyl ester (N-Ac-Met-OCH 3 ) are investigated in aqueous solution. Upon electron transfer from the methionine residue of N-AcMet-OCH 3 to 3 CB*, the resulting sulfur radical cation undergoes further reactions:(1) back electron transfer, (2) escape of the radical ions from the solvent cage, or (3) proton transfer and escape of the radicals. The yields and paths of these reactions are shown to depend strongly on the pH of the solution, and, similar to the previously reported results for dipeptides (Met-Gly and Gly-Met), on the structural nature of the methionine substituents. In the experiments performed in this work, low quencher concentrations were used to avoid formation of intermolecular transients (e.g., dimeric sulfur-centered radical cation (S;S) ? ). Under these experimental conditions, the one-electron oxidized sulfur does not seem to become stabilized in an (S;N) ? three-electron bonded intramolecular complex. The proposed mechanism is further supported by the stable products analysis. A detailed mechanism involving characterization of the transients is discussed and compared to that of methionine and methionine-containing dipeptides (Met-Gly and Gly-Met). Moreover, a newly installed transient absorption laser system is described in details.

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Computational Characterization of Sulfur−Oxygen Three-Electron-Bonded Radicals in Methionine and Methionine-Containing Peptides: Important Intermediates in One-Electron Oxidation Processes

Cited by 37 publications

References 104 publications

Generation of soluble oligomeric β-amyloid species via copper catalyzed oxidation with implications for Alzheimer’s disease: A DFT study

Generation of soluble oligomeric β-amyloid species via copper catalyzed oxidation with implications for Alzheimer’s disease: A DFT study

Roles of multiple-proton transfer pathways and proton-coupled electron transfer in the reactivity of the bis -Fe ^IV state of MauG

Photosensitized oxidation of methionine derivatives. Laser flash photolysis studies

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Computational Characterization of Sulfur−Oxygen Three-Electron-Bonded Radicals in Methionine and Methionine-Containing Peptides: Important Intermediates in One-Electron Oxidation Processes

Cited by 37 publications

References 104 publications

Generation of soluble oligomeric β-amyloid species via copper catalyzed oxidation with implications for Alzheimer’s disease: A DFT study

Generation of soluble oligomeric β-amyloid species via copper catalyzed oxidation with implications for Alzheimer’s disease: A DFT study

Roles of multiple-proton transfer pathways and proton-coupled electron transfer in the reactivity of the bis -Fe IV state of MauG

Photosensitized oxidation of methionine derivatives. Laser flash photolysis studies

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Roles of multiple-proton transfer pathways and proton-coupled electron transfer in the reactivity of the bis -Fe ^IV state of MauG