Intramolecular Sulfur−Oxygen Bond Formation in Radical Cations of <i>N</i>-Acetylmethionine Amide

Schöneich, Christian; Pogocki, Dariusz; Wisniowski, Pawel; Hug, and Gordon L.; Bobrowski, Krzysztof

doi:10.1021/ja0012218

Cited by 61 publications

(91 citation statements)

References 25 publications

(33 reference statements)

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“…The bimolecular rate constant for Reaction (6) was determined by the kinetic analysis of the Met 2 [S;S] ? decay at 480 nm (k 6 = 2.2 9 10 8 dm 3 mol -1 s -1 ).…”

Section: Met 2 [S;s] ? As An Oxidantmentioning

confidence: 99%

“…For small Met-containing peptides, the one-electron oxidation of an N-or C-terminal Met yields sulfide radical cations. These cations can stabilize via the respective formation of sulfur-nitrogen or sulfuroxygen three-electron bonds [5][6][7][8]. However, the nucleophilic sulfur atom in the side chain of Met is very susceptible to oxidation.…”

Section: Introductionmentioning

confidence: 99%

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Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine

Lin

Muroya

et al. 2011

Res Chem Intermed

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The oxidation processes of the radiation-generated, three-electronbonded intermediates AcMet 2 [S;S] ? and AcMet [S;Br] were investigated by pulse radiolysis via their reactions with tryptophan (TrpH). These intermediates were derived from N-acetyl-methionine amide (N-AcMetNH 2 ) and N-acetylmethionine methyl ester (N-AcMetOMe). The bimolecular rate constant k of the reaction between each intermediate and L-tryptophan (TrpH) was measured. For N-AcMetNH 2 , k for the reaction of AcMet 2 [S;S] ? with TrpH were 3.4 9 10 8 and 2.2 9 10 8 dm 3 mol -1 s -1 at pH = 1 and 4.5, respectively. For N-AcMetOMe, k for the reaction of AcMet 2 [S;S] ? with TrpH were 4.0 9 10 8 and 2.8 9 10 8 dm 3 mol -1 s -1 at pH 1 and 4.5, respectively. The rate constants for the intermolecular transformation of Met [S;Br] into TrpH ? or Trp were also estimated. For N-AcMetNH 2 , k for the reaction of AcMet 2 [S;Br] with TrpH were 2.6 9 10 8 and 3.3 9 10 8 dm 3 mol -1 s -1 at pH 1 and 4.5, respectively. Related mechanisms were discussed.

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“…The bimolecular rate constant for Reaction (6) was determined by the kinetic analysis of the Met 2 [S;S] ? decay at 480 nm (k 6 = 2.2 9 10 8 dm 3 mol -1 s -1 ).…”

Section: Met 2 [S;s] ? As An Oxidantmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine

Lin

Muroya

et al. 2011

Res Chem Intermed

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“…This is where the conductivity method was able to prove useful particularly when one of these species (normally S;O ? ) was charged and the other (S;N) was not [13,14]. Additionally, by weighting the conductivity results and by using these weighted results as another of the linear equations in the set, i.e., Eq.…”

Section: Contrasting Multilinear Regression and Factor Analysismentioning

confidence: 99%

“…However, two studies showed such three-electron bonds could be formed [13,14]. These studies involved linear peptides which were special cases or which had chemical modifications to void interaction of the sulfur radicals with lone pairs on terminal groups.…”

Section: Introductionmentioning

confidence: 99%

Factor analysis of transient spectra. Free radicals in cyclic dipeptides containing methionine

et al. 2009

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Factor analysis is introduced and applied to resolving puzzling behavior in the free-radical chemistry of the cyclic dipeptide cyclo-(D-Met-L-Met). Previously, spectral analysis of the transient absorption spectra, following the hydroxyl radical-induced oxidation of cyclo-(D-Met-L-Met), failed to match expectations seen when transient conductivity was used to monitor the same reaction sequence. In the current work, factor analysis is used to show that a radical cation is formed via the stabilization of the oxidized sulfur through the formation of two-centered three-electron bonds with the lone pairs on oxygen. This previously undetected radical resolves the discrepancy between transient absorption and transient conductivity observations.

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“…Such neighboring group participation in the oxidation of Met not only stabilizes the corresponding radical cation (Met > S þ ) but may also render the reduction potential of Met less positive, and therefore facilitate its oxidation [12]. Moreover, the reactions of two intermediates, Met > S þ and Met > S[OH within particular peptide and protein domains are influenced by groups such as carboxylate, amino, hydroxyl, and amide functionalities [13][14][15][16]. So far, the formation of sulfoxide in the radiolytic study of model peptides under anaerobic conditions was attributed to HO attack at the sulfur of Met residue [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Radiation chemical studies of Gly-Met-Gly in aqueous solution

Barata‐Vallejo

Ferreri

Zhang

et al. 2016

Free Radical Research

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Important biological consequences are related to the reaction of HO radicals with methionine (Met). Several fundamental aspects remain to be defined when Met is an amino acid residue incorporated in the interior of peptides and proteins. The present study focuses on Gly-Met-Gly, the simplest peptide where Met is not a terminal residue. The reactions of HO with Gly-Met-Gly and its N-acetyl derivative were studied by pulse radiolysis technique. The transient absorption spectra were resolved into contributions from specific components of radical intermediates. Moreover, a detailed product analysis is provided for the first time for Met-containing peptides in radiolytic studies to support the mechanistic proposal. By parallel radiolytical and electrochemical reactions and consequent product identification, the formation of sulfoxide attributed to the direct HO radical attack on the sulfide functionality of the Met residue could be excluded, with the in situ generated hydrogen peroxide responsible for this oxidation. LC-MS and high resolution MS/MS were powerful analytical tools to envisage the structures of five products, thus allowing to complete the mechanistic picture of the overall Met-containing peptide reactivity. ARTICLE HISTORY

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Intramolecular Sulfur−Oxygen Bond Formation in Radical Cations of N-Acetylmethionine Amide

Cited by 61 publications

References 25 publications

Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine

Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine

Factor analysis of transient spectra. Free radicals in cyclic dipeptides containing methionine

Radiation chemical studies of Gly-Met-Gly in aqueous solution

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