Reactions of bis-μ-iodo-bis(dinitrosyliron) with halide ions and with thiols: An electron paramagnetic resonance study

Butler, Anthony R.; Glidewell, Christopher; Hyde, Andrew; Walton, John C.

doi:10.1016/s0277-5387(00)84503-9

Cited by 16 publications

(19 citation statements)

References 11 publications

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“…Enzymatic studies documenting the loss of iron-sulfur enzymatic function have supported this possibility further (64) and suggest close analogy to the CAM system reported here. The EPR properties of small molecular weight inorganic complexes containing iron-nitrosyl groups have been described (34)(35)(36)(39)(40)(41)(42)(43)(44)(45)(46), and these species exhibit spectra that are quite similar to those reported here. At the present time, it is unknown whether the species that gives rise to the spectra reported here is protein-bound or a smaller complex, perhaps similar in structure to Roussin's salts.…”

Section: Discussionsupporting

confidence: 72%

“…This result raises the possibility that at least part of the signal may be due to the presence of a small molecular weight complex of iron, nitric oxide, and thiolate anion-containing ligand(s). The EPR properties of such small molecular weight complexes have been described previously, and the spectra resemble those presented here (34)(35)(36)(39)(40)(41)(42)(43)(44)(45)(46), although the molecular nature of the species giving rise to these signals has not been delineated.…”

Section: Resultssupporting

confidence: 55%

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EPR demonstration of iron-nitrosyl complex formation by cytotoxic activated macrophages.

Lancaster

Hibbs

1990

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

476

218

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Activated macrophage cytotoxicity is characterized by loss of intracellular iron and inhibition of certain enzymes that have catalytically active nonheme-iron coordinated to sulfur. This phenomenon involves the oxidation of one of the terminal guanidino nitrogen atoms of L-arginine, which results in the production of citrulline and inorganic nitrogen oxides (NO-, NO5, and NO). We report here the results of an electron paramagnetic resonance spectroscopic study performed on cytotoxic activated macrophage (CAM) effector cells, which develop the same pattern of metabolic inhibition as their targets. Examination of activated macrophages from mice infected with Mycobacterium bovis (strain bacillus CalmetteGuerin) that were cultured in medium with lipopolysaccharide and L-arginine showed the presence of an axial signal at g = 2.039, which is similar to previously described iron-nitrosyl complexes formed from the destruction of iron-sulfur centers by nitric oxide (NO). Inhibition of the L-arginine-dependent pathway by addition of NG-monomethyl L-arginine (methyl group on a terminal guanidino nitrogen) inhibits the production of nitrite, nitrate, citrulline, and the g = 2.039 signal. Comparison of the hyperfine structure of the signal from cells treated with L-arginine with terminal guanidino nitrogen atoms of natural abundance N'4 atoms or labeled with N'5 atoms showed that the nitrosyl group in this paramagnetic species arises from one of these two atoms. These results show that loss of iron-containing enzyme function in CAM is a result of the formation of iron-nitrosyl complexes induced by the synthesis of nitric oxide from the oxidation of a terminal guanidino nitrogen atom of L-arginine.

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Section: Discussionsupporting

confidence: 72%

Section: Resultssupporting

confidence: 55%

EPR demonstration of iron-nitrosyl complex formation by cytotoxic activated macrophages.

Lancaster

Hibbs

1990

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

476

218

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“…However, evidence appeared suggesting that DNIC are not due to mitochondrial iron-sulfur complexes (9,50). In addition, it has been demonstrated that DNIC are relatively promiscuous regarding the two ligands other than the nitrosyls; in fact, indistinguishable EPR signals are obtained whether the additional ligands are halogens, nitrogen, oxygen, or sulfur groups (51)(52)(53)(54). The results here suggest that the iron observed in cells and tissues exposed to exogenous and endogenous ⅐ NO is derived from the CIP.…”

Section: Discussionmentioning

confidence: 63%

Nitric Oxide-induced Conversion of Cellular Chelatable Iron into Macromolecule-bound Paramagnetic Dinitrosyliron Complexes

Toledo

Bosworth

Hennon

et al. 2008

Journal of Biological Chemistry

107

139

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One of the most important biological reactions of nitric oxide (nitrogen monoxide, ⅐ NO) is its reaction with transition metals, of which iron is the major target. This is confirmed by the ubiquitous formation of EPR-detectable g ‫؍‬ 2.04 signals in cells, tissues, and animals upon exposure to both exogenous and endogenous ⅐ NO. The source of the iron for these dinitrosyliron complexes (DNIC), and its relationship to cellular iron homeostasis, is not clear. Evidence has shown that the chelatable iron pool (CIP) may be at least partially responsible for this iron, but quantitation and kinetic characterization have not been reported. In the murine cell line RAW 264.7, ⅐ NO reacts with the CIP similarly to the strong chelator salicylaldehyde isonicotinoyl hydrazone (SIH) in rapidly releasing iron from the iron-calcein complex. SIH pretreatment prevents DNIC formation from ⅐ NO, and SIH added during the ⅐ NO treatment "freezes" DNIC levels, showing that the complexes are formed from the CIP, and they are stable (resistant to SIH). DNIC formation requires free ⅐ NO, because addition of oxyhemoglobin prevents formation from either ⅐ NO donor or S-nitrosocysteine, the latter treatment resulting in 100-fold higher intracellular nitrosothiol levels. EPR measurement of the CIP using desferroxamine shows quantitative conversion of CIP into DNIC by ⅐ NO. In conclusion, the CIP is rapidly and quantitatively converted to paramagnetic large molecular mass DNIC from exposure to free ⅐ NO but not from cellular nitrosothiol. These results have important implications for the antioxidative actions of ⅐ NO and its effects on cellular iron homeostasis.Nitric oxide (nitrogen monoxide, ⅐ NO) is a multifunctional small radical molecule responsible for a remarkable array of physiological and pathophysiological phenomena (1). Although ⅐ NO gives rise to a complex array of reactive species (2) in the biological milieu, ⅐ NO itself reacts directly with only a small number of targets. These targets are either species with unpaired electrons or transition metals; the origin of this reactivity pattern lies in the ability of these targets to stabilize the unpaired electron on ⅐ NO. In the case of transition metals, this stabilization occurs because of the strong interaction of ⅐ NO orbitals and the metal d-orbitals (3). Formation of metal-nitrosyls in biological systems can give rise to several paramagnetic species, which can be observed by EPR spectroscopy, and has been utilized to glean important information regarding the biological actions of ⅐ NO (4). In particular, exposure of cells or tissues to ⅐ NO (either exogenously administered or endogenously synthesized) results in the ubiquitous appearance of a "g ϭ 2.04" axial EPR signal, which has been assigned to iron in square planar coordination with two nitrosyl ligands (denoted "dinitrosyliron complexes" (DNIC) 3 (5). The source of this iron, the nature of the other iron ligands, and the origin of their formation are not clear.The intracellular labile or chelatable iron pool (CIP) is a smal...

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“…The electronic spectra were calculated with the UB3LYP method, which is the one accessible in The calculations of electronic structure and spectra of [(RS) 2 Fe(NO) 2 ] À (I) and [(RS) 3 Fe(NO)] À (II) with a methyl group as R were performed. These species are formed in reactions of iron salts with nitric oxide and thiols [2,[18][19][20].…”

Section: Ga Ussianmentioning

confidence: 99%

“…The geometry of IA was also optimized with the UB3LYP method. As the experimental spin of [(RS) 2 Fe(NO) 2 ] À amounts to 1/2 [1,[18][19][20], the calculations were performed with S ¼ 1=2.…”

Section: [(Ch 3 S) 2 Fe(no) 2 ] à (I)mentioning

confidence: 99%

Structure and UV–Vis spectroscopy of nitrosylthiolatoferrate mononuclear complexes

Jaworska

Stasicka

2004

Journal of Organometallic Chemistry

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Reactions of bis-μ-iodo-bis(dinitrosyliron) with halide ions and with thiols: An electron paramagnetic resonance study

Cited by 16 publications

References 11 publications

EPR demonstration of iron-nitrosyl complex formation by cytotoxic activated macrophages.

EPR demonstration of iron-nitrosyl complex formation by cytotoxic activated macrophages.

Nitric Oxide-induced Conversion of Cellular Chelatable Iron into Macromolecule-bound Paramagnetic Dinitrosyliron Complexes

Structure and UV–Vis spectroscopy of nitrosylthiolatoferrate mononuclear complexes

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