E.S.R. of Spin-trapped Radicals in Aqueous Solutions of Amino Acids

Joshi, Avinash; Rustgi, Surendra N.; Moss, Harold; Riesz, Peter

doi:10.1080/09553007714550521

Cited by 62 publications

(43 citation statements)

References 21 publications

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“…In addition, when higher concentrations (0.1 M) of D,L-histidine are used and the reaction is carried out at pH 7, the spin adduct obtained is predominantly a triplet of doublets with hyperfine coupling constants aN = 1.57 mT and a& = 0.34 mT. These values are also consistent with previous data obtained for the spin trapping of histidyl radicals following the reaction of 'OH with histidine [24]. The results shown in fig.1 confirm that 'OH are formed at the concentrations of V02+ and Hz02 used.…”

Section: Resultssupporting

confidence: 89%

“…This computer simulation was generated using hyperfine coupling values of 1.52 mT, 0.19 mT, 0.38 mT, 0.19 mT and 0.073 mT for the primary nitroxide nitrogen, the histidine nitrogen and the 3 histidine protons, respectively. These hyperfine coupling constants are consistent with the known spectral parameters for the histidyl radical adduct of MNP formed following 'OH reaction with histidine [24]. In addition, when higher concentrations (0.1 M) of D,L-histidine are used and the reaction is carried out at pH 7, the spin adduct obtained is predominantly a triplet of doublets with hyperfine coupling constants aN = 1.57 mT and a& = 0.34 mT.…”

Section: Resultssupporting

confidence: 80%

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Vanadyl‐induced Fenton‐like reaction in RNA

Carmichael¹

1990

FEBS Letters

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Vanadyl (VO*+) complexed to RNA reacts with hydrogen peroxide in a Fenton-like manner producing hydroxyl radicals ('OH). The hydroxyl radicals can be spin trapped with $5dimethyl-1-pyrroline-l-oxide (DMPO) forming the DMPO-OH spin adduct. In addition, in the presence of ethanol the formation of the hydroxyethyl radical adduct of DMPO (DMPO-ETOH) confirms the production of hydroxyl radicals by the RNA/ VO*' complex. When the reaction between the RNA/VO*+ complex and H202 is carried out in the presence of the spin trap 2-methyL2nitrosopro-pane (MNP), radicals produced in the reaction of 'OH with RNA are trapped. Base hydrolysis of the MNP-RNA adducts (pH 12) followed by a reduction in the pH to pH 7 after hydrolysis is complete, yields an MNP adduct with a well-resolved ESR spectrum identical to the ESR spectrum obtained from analogous experiments with poly U. The ESR spectrum consists of a triplet of sextets (uN = 1.48 mT, a,8=0.25 mT and &=0.14 mT), indicating that the unpaired nitroxide electron interacts with the nuclei of a b-nitrogen and b-hydrogen. The results suggest that the 'OH generated in the RNA/V02+ reaction with H,Oz add to the C(5) carbon of uracil forming a C(6) carbon centered radical. This radical is subsequently spin trapped by MNP.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 80%

Vanadyl‐induced Fenton‐like reaction in RNA

Carmichael¹

1990

FEBS Letters

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“…Possible candidates are the amino acids valine, isoleucine, leucine, threonine and proline. Data in the literature showed that MNP adducts of tertiary carbon-centred radicals with a hyperfine splitting between 16.3 and 16.7 G can be obtained on exposure of valine, leucine and isoleucine to hydroxyl radicals, generated by photolysis of H # O # [28]. Incubation of these amino acids with methaemoglobin and t-BuOOH in the presence of MNP did not give the formation of radical adducts.…”

Section: Oxidation Of Amino Acidsmentioning

confidence: 99%

“…Two radical adducts came from hydrogen abstraction from the methyl groups of each amino acid (Figures 7B and 7C). The non-equivalence in the hyperfine splitting constants of the β-protons can be explained by the presence of two asymmetrical conformers produced by internal steric hindrance ( [28], and references therein). The third species that was observed came from a tertiary carbon ( Figure 7D).…”

Section: Table 1 Hyperfine Coupling Constants Of Radical Adducts Genementioning

confidence: 99%

Formation of peroxide- and globin-derived radicals from the reaction of methaemoglobin and metmyoglobin with t-butyl hydroperoxide: an ESR spin-trapping investigation

Zee

1997

Biochemical Journal

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The reaction of human methaemoglobin and horse metmyoglobin with t-butyl hydroperoxide (t-BuOOH) was investigated with the ESR spin-trapping technique. With the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) the formation of peroxyl, alkoxyl and methyl radicals derived from t-BuOOH could be detected. The relative contributions of these radicals were determined at various DMPO concentrations by computer simulation. From these data it could be concluded that the alkoxyl radical was the initial radical produced, which indicates that the hydroperoxide is cleaved homolytically. Further investigations, with the nitroso spin trap 2-methyl-2-nitrosopropane (MNP), showed the formation of globin-centred radicals. Non-specific proteolysis of the MNP adducts revealed isotropic three-line

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“…Among spin trapping studies, 2-methyl-2-nitrosopropane (MNP) has been utilized as one of the most informative spin traps (1)(2)(3)(4)(5). However, it is known that when the method of spin trapping with MNP is applied to y-radiolysis in aqueous solutions, esr spectra obtained are often too complicated to be analyzed accurately.…”

Section: Introductionmentioning

confidence: 99%

Electron spin resonance of spin trapped radicals in γ-irradiated polycrystalline dipeptides. Chromatographic separation of radicals

Makino¹,

Riesz²

1982

Can. J. Chem.

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KEIsUKE MAKINO and PETER RIESZ. Can. J. Chem. 60, 1480Chem. 60, (1982. Polycrystalline dipeptides (glycyl-glycine, glycyl-L-valine, glycyl-L-leucine, L-alanyl-glycine, and L-prolyl-L-alanine) were y-irradiated at room temperature in the absence of air. Subsequently they were dissolved in aqueous solutions containing 2-methyl-2-nitrosopropane as the spin trap. From the esr spectra of the nitroxide radicals separated by high-performance liquid chromatography, structural assignments of the radicals were made. For glycyl peptides, H-abstraction from the a-carbon atoms of the carboxyl terminal residues and from the side-chains were observed. For L-alanyl-glycine, H-abstraction from the glycyl residue and the formation of the deamination radical could be shown to occur. For L-prolyl-L-alanine, the ring opening (deamination) reaction, decarboxylation and H-abstraction from the C-terminal a-carbon were seen. KEISUKE MAKINO et PETER RIESZ. Can. J. Chem. 60, 1480 (1982). On a irradie aux rayons y, a la temperature ambiante et en I'absence d'air, les dipeptides polycristallins suivants:On les a ensuite dissous dans des solutions aqueuses contenant le capteur de spin, methyl-2 nitroso-2 propane. A partir des spectres de rpe des radicaux nitroxydes, skpares par chromatographie en phase liquide a haute performance, on a pu determiner les structures des radicaux. On a observe, dans le cas des peptides glycidiques, I'klimination d'un hydrogene partir des atomes de carbone en a du residue terminal carbxyle e t a partir des chaines laterales. Dans le cas du L-alanyl-glycine, on peut montrer qu'il se k~roduit unr 4limination d'hydrogene a partir du risidu glycyle et la formation d'un radical de desamination. Dans le cas du L-prolyl-L-alanine, on a observe une reaction d'ouverture de cycle (desamination), de decarboxylation et d'0limination d'un atome d'hydrogene a partir du carbone terminal en position 2.[Traduit par le journal]

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E.S.R. of Spin-trapped Radicals in Aqueous Solutions of Amino Acids

Cited by 62 publications

References 21 publications

Vanadyl‐induced Fenton‐like reaction in RNA

Vanadyl‐induced Fenton‐like reaction in RNA

Formation of peroxide- and globin-derived radicals from the reaction of methaemoglobin and metmyoglobin with t-butyl hydroperoxide: an ESR spin-trapping investigation

Electron spin resonance of spin trapped radicals in γ-irradiated polycrystalline dipeptides. Chromatographic separation of radicals

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