Pulse Radiolysis of 2-Mercaptoethanol in Oxygenated Aqueous Solution. Generation and Reactions of the Thiylperoxyl Radical

“…The resulting peroxylradical, ONOO °, is expected to oxidize thiols but most probably via an overall two-electron oxidation (reaction 3) [35]. The product °NO2 reacts efficiently with thiols [36] with an estimated overall rate constant in aqueous solution ofk 4 > 5 x 108 M-Is • -1 [37], where reaction 4 proceeds via intermediary adducts such CysS°(NO2)H and S-nitroso thiols [36].…”

Section: Discussionmentioning

confidence: 99%

Accumulation of nitrotyrosine on the SERCA2a isoform of SR Ca‐ATPase of rat skeletal muscle during aging: a peroxynitrite‐mediated process?

Viner¹,

Ferrington²,

Hühmer³

et al. 1996

FEBS Letters

132

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The SR Ca-ATPase in skeletal muscle SR vesicles isolated from young adult (5 months) and aged (28 months) rats was analyzed for nitrotyrosine. Only the SERCA2a isoform contained significant amounts with approximately one and four nitrotyrosine residues per young and old Ca-ATPase, respectively. The in vitro exposure of SR vesicles of young rats to peroxynitrite yielded selective nitration of the SERCA2a Ca-ATPase even in the presence of excess SERCAla. No nitration was observed during the exposure of SR vesicles to nitric oxide in the presence of 02. These data suggest the in vivo presence of peroxynitrite in skeletal muscle. The greater nitrotyrosine content of SERCA2a from aged tissue implies an age-associated increase in susceptibility to oxidation by this species.

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“…13). Intramolecular H transfer from a-C-H groups to sulfur has now also been reported in homocysteine and cysteine (14) and 2-mercaptoethanol (15). Also Zhao et al have shown (14) that S-centered radicals are able to abstract a-C-H hydrogen atoms from the anions of glycine and alanine, and have estimated a value of 356 kJ mol-' for the tertiary a-C-H bond dissociation energy of H2NC(CH3)HC02-.…”

mentioning

confidence: 82%

Oxidative damage to the glycyl α-carbon site in proteins: an ab initio study of the C—H bond dissociation energy and the reduction potential of the C-centered radical

Armstrong¹,

Yu²,

Rauk³

1996

Can. J. Chem.

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The C—H bond dissociation energies (DC—H) of a series of model glycyl proteins were derived from selected isodesmic reactions based on high level ab initio calculations. At 298 K, the recommended values of DC—H, in kJ mol−1 are: NH2CH2CHO, 308; NH2CH2C(O)NH2, 336; HC(O)NHCH2CHO, 331; HC(O)NHCH2C(O)NH2, 350; CH3C(O)NHCH2C(O)NH2, 347; HC(O)NHCH2C(O)NHCH3, 349; and CH3C(O)NHCH2C(O)NHCH3, 346. The average of the last four values, 348 kJ mol−1, is the predicted bond dissociation energy of the α-C—H bond of a glycyl protein. The reduction potential in aqueous medium at 298 K and pH 7 for the process, R• + H+ + e− = RH, where R• = XNHCH•C(O)Y and X and Y represent extension of the protein chain, is E0′ 0.8 V. This result suggests that the α-C—H bond of a glycyl protein is susceptible to attack by RS•, ROO•, tyrosyl, and OH• radicals, whose reduction potentials for the analogous process are higher. The present study has established that the molecule HC(O)NHCHRC(O)NH2 (R = an amino acid side chain) serves as an accurate model for the α-C environment of an amino acid residue in a protein, and that a reliable DC—H value for the α-C—H bond may be obtained from calculations on this model at the B3LYP/6-31G(D) level of theory in conjunction with an isodesmic reaction using neutral glycine as reference. Key words: glycine, peptide, amino acid, bond energy, radicals, ab initio, computation.

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Pulse Radiolysis of 2-Mercaptoethanol in Oxygenated Aqueous Solution. Generation and Reactions of the Thiylperoxyl Radical

Cited by 110 publications

References 14 publications

Reversibility in the Reaction of Cyclohexadienyl Radicals with Oxygen in Aqueous Solution

Reversibility in the Reaction of Cyclohexadienyl Radicals with Oxygen in Aqueous Solution

Accumulation of nitrotyrosine on the SERCA2a isoform of SR Ca‐ATPase of rat skeletal muscle during aging: a peroxynitrite‐mediated process?

Oxidative damage to the glycyl α-carbon site in proteins: an ab initio study of the C—H bond dissociation energy and the reduction potential of the C-centered radical

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