Reassignment of organic peroxyl radical adducts

Dikalov, Sergey; Mason, Ronald P.

doi:10.1016/s0891-5849(99)00134-3

Cited by 112 publications

(82 citation statements)

References 30 publications

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“…Lsr2 was disassociated from DNA by dialyzing against 50 mM phosphate (pH 7.4), 800 mM NaCl. Spin-trapping experiments and EPR measurements were performed as described previously (36,37), X-band EPR spectra were recorded at room temperature on a Bruker EleXsys E500 spectrometer fitted with a high sensitivity SHQ cavity. All spectra were recorded Ϸ3 min after the addition of Fe(II).…”

Section: Methodsmentioning

confidence: 99%

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

Colangeli

Haq

Arcus

et al. 2009

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

117

106

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Mycobacterium tuberculosis has evolved a number of strategies to survive within the hostile environment of host phagocytes. Reactive nitrogen and oxygen intermediates (RNI and ROI) are among the most effective antimycobacterial molecules generated by the host during infection. Lsr2 is a M. tuberculosis protein with histonelike features, including the ability to regulate a variety of transcriptional responses in mycobacteria. Here we demonstrate that Lsr2 protects mycobacteria against ROI in vitro and during macrophage infection. Furthermore, using macrophages derived from NOS ؊/؊ and Phox ؊/؊ mice, we demonstrate that Lsr2 is important in protecting against ROI but not RNI. The protection provided by Lsr2 protein is not the result of its ability to either bind iron or scavenge hydroxyl radicals. Instead, electron microscopy and DNAbinding studies suggest that Lsr2 shields DNA from reactive intermediates by binding bacterial DNA and physically protecting it. Thus, Lsr2 appears to be a unique protein with both histone-like properties and protective features that may be central to M. tuberculosis pathogenesis. In addition, evidence indicates that lsr2 is an essential gene in M. tuberculosis. Because of its essentiality, Lsr2 may represent an excellent candidate as a drug target.Mycobacterium tuberculosis ͉ ROI ͉ DPS ͉ DNA

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Section: Methodsmentioning

confidence: 99%

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

Colangeli

Haq

Arcus

et al. 2009

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

117

106

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“…[1][2][3][4] During this technique, a highly reactive free radical typically reacts with a double bond of a diamagnetic compound (the spin trap) to form a more stable radical (the spin adduct) which can be detected by EPr spectrometry. [5][6][7][8][9] Nitrones are the most frequently used compounds as spin trapping agents, and the spin adducts being, in this case, a nitroxide.…”

Section: Europeanmentioning

confidence: 99%

Characterization of Free Radical Spin Adducts of 5-Diisopropyloxy-Phosphoryl-5-Methyl-1-Pyrroline-N-Oxide Using Mass Spectrometry and ³¹P Nuclear Magnetic Resonance

Zoia

Argyropoulos

2010

Eur J Mass Spectrom (Chichester)

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All rights reserved EuroPEAN JourNAL of MASS SPEctroMEtry for many years, spin traps have been used to decrease the reactivity of free radicals in order for them to be identified and detected by electron paramagnetic resonance (EPr) spectrometry, thereby allowing the acquisition of abundant information on the production of such species in biological, biochemical and chemical systems. [1][2][3][4] During this technique, a highly reactive free radical typically reacts with a double bond of a diamagnetic compound (the spin trap) to form a more stable radical (the spin adduct) which can be detected by EPr spectrometry. [5][6][7][8][9] Nitrones are the most frequently used compounds as spin trapping agents, and the spin adducts being, in this case, a nitroxide. recent accounts 10 have demonstrated that phosphorus-containing spin traps give rise to radical adducts that have longer half-lives compared Characterization of free radical spin adducts of 5-diisopropyloxy-phosphoryl-5-methyl-1-pyrroline-N-oxide using mass spectrometry and 31 P nuclear magnetic resonance 5-Diisopropyloxy-phosphoryl-5-methyl-1-pyrroline-N-oxide (DIPPMPO) was used to trap a variety of free radicals and the stable compounds generated by the natural decomposition of the initially formed spin adducts were characterized by 31 P nuclear magnetic resonance (NMR) and mass spectrometry. Initially, the starting spin trap DIPPMPO was completely characterized using GC-MS and its fragmentation pathway was studied in detail. Then, DIPPMPO was used to trap an oxygen-centered free radical (the hydroxyl radical • OH) and two carbon-centered free radicals (methyl • CH 3 and 1-phenyl-ethanol-1-yl • CCH 3 (OH)Ph radicals). The 31 P NMR signals were thus assigned and the structures of adducts were studied and confirmed by mass spectrometry. Overall, the fragmentation pathways of the radical adducts proceed mainly via the loss of the diisopropyloxy(oxido)phosphoranyl radical. For the specific case of trapping•OH radicals, it is possible to visualize the rearrangement of the nitroxide radical adduct to its nitrone form as invoked in the literature. This spin trapping technique, coupled with 31 P NMR and MS, provides a tool for the identification of short-lived and low molecular weight free radicals present in a variety of processes.

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“…However, these experiments did not allow the unambiguous identification of the species resulting from the trapping of oxygen-centered radicals because the hyperfine coupling constants of the alkoxyl and alkylperoxyl radical adducts are virtually identical, as already reported in the literature. [22] Neither TTBNB nor DMPO allowed the trapping of alkoxyl radicals to be differentiated from the trapping of alkylperoxyl radicals.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, at temperatures higher than 250 K, reputedly only alkoxyl radical adducts are detected. [22,23] The discovery that the superoxide radical anion and hydroxyl radicals are involved in several human pathologies has stimulated the development of new selective spin-traps for the detection of these transient reactive intermediates. [24] DEPMPO, developed by Tordo and co-workers, [25] was likely to be ideally suited to probing the formation of all three types of radicals, that is, alkyl, alkoxyl, and alkylperoxyl radicals, during the dialkylzinc oxidation process.…”

Section: Resultsmentioning

confidence: 99%

Spin‐Trapping Evidence for the Formation of Alkyl, Alkoxyl, and Alkylperoxyl Radicals in the Reactions of Dialkylzincs with Oxygen

Maury

Feray

Bazin

et al. 2011

Chemistry A European J

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The reactions of dialkylzincs (Me(2)Zn, Et(2)Zn, and nBu(2)Zn) with oxygen have been investigated by EPR spectroscopy using spin-trapping techniques. The use of 5-diethoxyphosphoryl-5-methyl-1-pyrrroline N-oxide (DEPMPO) as a spin-trap has allowed the involvement of alkyl, alkylperoxyl, and alkoxyl radicals in this process to be probed for the first time. The relative ratio of the corresponding spin-adducts depends strongly on the nature of the R group, which controls the C-Zn bond dissociation enthalpy, and on the experimental conditions (excess of spin-trap compared with R(2)Zn and vice versa). The results have demonstrated that Et(2)Zn and, to a lesser extent, nBu(2)Zn are much better traps for oxygen-centered species than Me(2)Zn. When the dialkylzincs were used in excess with respect to the spin-trap, the concentration of the oxygen-centered radical adducts of DEPMPO was much lower for Et(2)Zn and nBu(2)Zn than for Me(2)Zn. A detailed reaction mechanism is discussed and C-Zn, O-Zn, and O-O bond dissociation enthalpies for the proposed reaction intermediates were calculated at the UB3LYP/6-311++G(3df,3pd)//UB3LYP/6-31G(d,p) level of theory to support the rationale.

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Reassignment of organic peroxyl radical adducts

Cited by 112 publications

References 30 publications

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

Characterization of Free Radical Spin Adducts of 5-Diisopropyloxy-Phosphoryl-5-Methyl-1-Pyrroline-N-Oxide Using Mass Spectrometry and ³¹P Nuclear Magnetic Resonance

Spin‐Trapping Evidence for the Formation of Alkyl, Alkoxyl, and Alkylperoxyl Radicals in the Reactions of Dialkylzincs with Oxygen

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Reassignment of organic peroxyl radical adducts

Cited by 112 publications

References 30 publications

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates

Characterization of Free Radical Spin Adducts of 5-Diisopropyloxy-Phosphoryl-5-Methyl-1-Pyrroline-N-Oxide Using Mass Spectrometry and 31P Nuclear Magnetic Resonance

Spin‐Trapping Evidence for the Formation of Alkyl, Alkoxyl, and Alkylperoxyl Radicals in the Reactions of Dialkylzincs with Oxygen

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Characterization of Free Radical Spin Adducts of 5-Diisopropyloxy-Phosphoryl-5-Methyl-1-Pyrroline-N-Oxide Using Mass Spectrometry and ³¹P Nuclear Magnetic Resonance