Computational survey of ligand properties on iron(III)–iron(II) redox potential: exploring natural attenuation of nitroaromatic compounds

Rizvi, Masood Ahmad; Mane, Manoj V.; Khuroo, Mohammad Akbar; Peerzada, Ghulam Mustafa

doi:10.1007/s00706-016-1813-8

Cited by 17 publications

(14 citation statements)

References 56 publications

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“…A modelling study estimated that Fe 2+ transfers 1.3 electrons to the electron-rich catechol ring 49 , which might result in destabilization of the complex. The promotion of Fe 2+ oxidation by Epi might be further explained by the fact that ligands with harder donor sites are better Fe 3+ stabilizers and decrease the redox potential of Fe 3+ /Fe 2+ pair 23 . The stability constants for catechol complexes with Fe 3+ are significantly higher than complexes with Fe 2+ 22 .…”

Section: Discussionmentioning

confidence: 99%

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Korać

Stanković

Stanić

et al. 2018

Sci Rep

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Coordinate and redox interactions of epinephrine (Epi) with iron at physiological pH are essential for understanding two very different phenomena – the detrimental effects of chronic stress on the cardiovascular system and the cross-linking of catecholamine-rich biopolymers and frameworks. Here we show that Epi and Fe3+ form stable high-spin complexes in the 1:1 or 3:1 stoichiometry, depending on the Epi/Fe3+ concentration ratio (low or high). Oxygen atoms on the catechol ring represent the sites of coordinate bond formation within physiologically relevant bidentate 1:1 complex. Redox properties of Epi are slightly impacted by Fe3+. On the other hand, Epi and Fe2+ form a complex that acts as a strong reducing agent, which leads to the production of hydrogen peroxide via O2 reduction, and to a facilitated formation of the Epi–Fe3+ complexes. Epi is not oxidized in this process, i.e. Fe2+ is not an electron shuttle, but the electron donor. Epi-catalyzed oxidation of Fe2+ represents a plausible chemical basis of stress-related damage to heart cells. In addition, our results support the previous findings on the interactions of catecholamine moieties in polymers with iron and provide a novel strategy for improving the efficiency of cross-linking.

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Section: Discussionmentioning

confidence: 99%

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Korać

Stanković

Stanić

et al. 2018

Sci Rep

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“…The relative affinities of a given ligand for Fe(III) and Fe(II) can be correlated to the Fe(III)/Fe(II) reduction potential for the corresponding complex (Table S3). 59 In general, ligands that employ more electron-donating atoms exhibit higher affinity (lower K d values) for Fe(III) relative to Fe(II) and lower reduction potential ( E º) values. In an extreme case, the tris-catecholate siderophore Ent with six negatively charged oxygen-donating ligands (Fig.…”

Section: Discussionmentioning

confidence: 99%

Human calprotectin affects the redox speciation of iron

Nakashige

Nolan

2017

Metallomics

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We report that the metal-sequestering human host-defense protein calprotectin (CP, S100A8/S100A9 oligomer) affects the redox speciation of iron (Fe) in bacterial growth media and buffered aqueous solution. Under aerobic conditions and in the absence of an exogenous reducing agent, CP-Ser (S100A8(C42S)/S100A9(C3S) oligomer) depletes Fe from three different bacterial growth media preparations over a 48-h timeframe (T = 30 °C). The presence of the reducing agent β-mercaptoethanol accelerates this process and allows CP-Ser to deplete Fe over a ≈1-h timeframe. Fe-depletion assays performed with metal-binding-site variants of CP-Ser show that the hexahistidine (His6) site, which coordinates Fe(II) with high affinity, is required for Fe depletion. An analysis of Fe redox speciation in buffer containing Fe(III) citrate performed under aerobic conditions demonstrates that CP-Ser causes a time-dependent increase in the [Fe(II)]/[Fe(III)] ratio. Taken together, these results indicate that the hexahistidine site of CP stabilizes Fe(II) and thereby shifts the redox equilibrium of Fe to the reduced ferrous state under aerobic conditions. We also report that the presence of bacterial metabolites affects the Fe-depleting activity of CP-Ser. Supplementation of bacterial growth media with an Fe(III)-scavenging siderophore (enterobactin, staphyloferrin B, or desferrioxamine B) attenuates the Fe-depleting activity of CP-Ser. This result indicates that formation of Fe(III)-siderophore complexes blocks CP-mediated reduction of Fe(III) and hence the ability of CP to coordinate Fe(II). In contrast, the presence of pyocyanin (PYO), a redox-cycling phenazine produced by Pseudomonas aeruginosa that reduces Fe(III) to Fe(II), accelerates Fe depletion by CP-Ser under aerobic conditions. These findings indicate that the presence of microbial metabolites that contribute to metal homeostasis at the host/pathogen interface can affect the metal-sequestering function of CP.

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“…This method has been widely used in studying several metal complexes, including those involving iron species . Jaworska et al studied the iron‐EDTA complex combined with nitrogen monoxide, and Neese and Solomon studied the complex combined with oxygen, while Rizvi et al studied the complex with nitroaromatic compounds. However, the iron complexes that were formed had stable eight coordination complexes and DTPA had formed a nine coordination bond with a metal ion, which is rare compared to the popular octahedral six coordination number complexes.…”

Section: Introductionmentioning

confidence: 99%

Molecular and electronic structure elucidation of Fe²⁺/Fe³⁺ complexed chelators used in iron sulphide scale removal in oil and gas wells

et al. 2019

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Quantum chemical calculations based on DFT are employed to study the electronic structure and binding affinity of chelators used in the removal of iron sulphide scales. Three chelating agents, EDTA, HEDTA, and DTPA, are considered in this work. The complexes showed a coordination number of 5, 6, and 7 for Fe 2þ and Fe 3þ ions with HEDTA, EDTA, and DTPA, respectively. However, regarding EDTA, Fe 3þ could coordinate with an additional water molecule and form a seven-coordinate complex. The calculated binding energies agreed with the experimental stability constants of the chelators in the order DTPA > EDTA > HEDTA for both Fe 2þ /Fe 3þ complexes. The binding free energies showed a spontaneous reaction with Fe 3þ having a stronger binding affinity than Fe 2þ due to electrostatic forces. This investigation provides insights regarding how chelators that are applied in iron sulphide scale removal may be designed by increasing the number of nitrogen atoms to above the number of carboxylate groups.

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Computational survey of ligand properties on iron(III)–iron(II) redox potential: exploring natural attenuation of nitroaromatic compounds

Cited by 17 publications

References 56 publications

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Human calprotectin affects the redox speciation of iron

Molecular and electronic structure elucidation of Fe²⁺/Fe³⁺ complexed chelators used in iron sulphide scale removal in oil and gas wells

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Computational survey of ligand properties on iron(III)–iron(II) redox potential: exploring natural attenuation of nitroaromatic compounds

Cited by 17 publications

References 56 publications

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Human calprotectin affects the redox speciation of iron

Molecular and electronic structure elucidation of Fe2+/Fe3+ complexed chelators used in iron sulphide scale removal in oil and gas wells

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Molecular and electronic structure elucidation of Fe²⁺/Fe³⁺ complexed chelators used in iron sulphide scale removal in oil and gas wells