Iron: Metabolism, toxicity and therapy

Fontecave, Marc; Pierre, J.-L.

doi:10.1016/0300-9084(93)90126-d

Cited by 81 publications

(56 citation statements)

References 13 publications

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“…In addition, the higher Fe(III) chelating efficacy (higher pFe values) of the O,O-donor ligands, as compared with O,S-analogues, is accompanied by an increased difficulty of the reduction of the corresponding iron chelates (E red FeL 3 −0.6 and −0.9 V, see Table 2); however, in any case, these chelates are much more difficult to reduce than the Fe(III)-EDTA chelate (E red FeEDTA −0.1 V) [42] and so less OH • is produced and a lower deoxyribose degradation results. Therefore, the above results give support to the conclusion that, in reaction mixtures containing EDTA, the inhibition of deoxyribose degradation, for lower ligand concentrations, results from the scavenging of OH • generated in free solution, whereas for higher ligand concentrations the inhibition is due to iron chelation by ligands forming metal complexes in a less redox-active form compared with EDTA-metal complex.…”

Section: Hydroxyl Radical Scavenging Activitymentioning

confidence: 97%

Hydroxy(thio)pyrone and hydroxy(thio)pyridinone iron chelators: Physico-chemical properties and anti-oxidant activity

Chaves¹,

Canário²,

Carrasco³

et al. 2012

Journal of Inorganic Biochemistry

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Section: Hydroxyl Radical Scavenging Activitymentioning

confidence: 97%

Hydroxy(thio)pyrone and hydroxy(thio)pyridinone iron chelators: Physico-chemical properties and anti-oxidant activity

Chaves¹,

Canário²,

Carrasco³

et al. 2012

Journal of Inorganic Biochemistry

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“…Could iron be an endogenous regulator of TH activity? Free iron in the cytosol is kept at a low level (probably below 10 M) by incorporation into protein chelators like ferritin (50). Human brain TH extracted from the caudate nucleus is activated more than 10-fold by incubation with ferrous ion (51), and Haavik et al (34) have proposed that a significant fraction of human TH is not saturated with iron in vivo.…”

Section: Fig 6 Inhibition Of Dth Activity By Dopaminementioning

confidence: 99%

Differential Regulation of Drosophila Tyrosine Hydroxylase Isoforms by Dopamine Binding and cAMP-dependent Phosphorylation

Vié

Cigna

Toci

et al. 1999

Journal of Biological Chemistry

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Tyrosine hydroxylase (TH) catalyzes the first step in dopamine biosynthesis in Drosophila as in vertebrates. We have previously reported that tissue-specific alternative splicing of the TH primary transcript generates two distinct TH isoforms in Drosophila, DTH I and DTH II (Birman, S., Morgan, B., Anzivino, M., and Hirsh, J. (1994) J. Biol. Chem. 269, 26559 -26567). Expression of DTH I is restricted to the central nervous system, whereas DTH II is expressed in non-nervous tissues like the epidermis. The two enzymes present a single structural difference; DTH II specifically contains a very acidic segment of 71 amino acids inserted in the regulatory domain. We show here that the enzymatic and regulatory properties of vertebrate TH are generally conserved in insect TH and that the isoform DTH II presents unique characteristics. The two DTH isoforms were expressed as apoenzymes in Escherichia coli and purified by fast protein liquid chromatography. The recombinant DTH isoforms are enzymatically active in the presence of ferrous iron and a tetrahydropteridine co-substrate. However, the two enzymes differ in many of their properties. DTH II has a lower K m value for the cosubstrate (6R)-tetrahydrobiopterin and requires a lower level of ferrous ion than DTH I to be activated. The two isoforms also have a different pH profile. As for mammalian TH, enzymatic activity of the Drosophila enzymes is decreased by dopamine binding, and this effect is dependent on ferrous iron levels. However, DTH II appears comparatively less sensitive than DTH I to dopamine inhibition. The central nervous system isoform DTH I is activated through phosphorylation by cAMPdependent protein kinase (PKA) in the absence of dopamine. In contrast, activation of DTH II by PKA is only manifest in the presence of dopamine. Site-directed mutagenesis of Ser 32 , a serine residue occurring in a PKA site conserved in all known TH proteins, abolishes phosphorylation of both isoforms and activation by PKA. We propose that tissue-specific alternative splicing of TH has a functional role for differential regulation of dopamine biosynthesis in the nervous and non-nervous tissues of insects.Tyrosine hydroxylase (TH 1 ) (tyrosine 3-monooxygenase, EC 1.14.16.2) is an eukaryotic enzyme catalyzing the first and rate-limiting step in dopamine and other catecholamine biosynthesis, i.e. the hydroxylation of the monophenol amino acid L-tyrosine to produce the ortho-diphenol L-dihydroxyphenylalanine (2, 3). The enzyme is active in the presence of ferrous iron, O 2 , and a tetrahydrobiopterin co-substrate. A single gene encodes TH, which is required for embryonic development and survival in mammals (4, 5). In vertebrates, TH activity is exquisitely regulated at each step of its expression: control of gene transcription, RNA alternative processing, mRNA stability, and direct modulation of the enzyme by catecholamine feedback inhibition and protein kinase activation (6 -8).In contrast, much less is known on the regulatory properties of tyrosine hydroxylase in insects. Muta...

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“…It affects properties like turbidity, stimulates bacterial growth, and can react chemically with other materials in the aquatic environment. Reactions of iron cations and compounds with oxygen can be particularly important when they produce oxygen radicals and peroxides, which can damage DNA (Lucassen et al, 2000;Fontecave and Pierre, 1993;Papanikolaou and Pantopoulos, 2005).…”

Section: Introductionmentioning

confidence: 99%

Biosorption of Cr(III) and Fe(III) in single and binary systems onto pretreated orange peel

Lugo-Lugo

Dı́az

Ureña-Núñez

et al. 2012

Journal of Environmental Management

105

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Iron: Metabolism, toxicity and therapy

Cited by 81 publications

References 13 publications

Hydroxy(thio)pyrone and hydroxy(thio)pyridinone iron chelators: Physico-chemical properties and anti-oxidant activity

Hydroxy(thio)pyrone and hydroxy(thio)pyridinone iron chelators: Physico-chemical properties and anti-oxidant activity

Differential Regulation of Drosophila Tyrosine Hydroxylase Isoforms by Dopamine Binding and cAMP-dependent Phosphorylation

Biosorption of Cr(III) and Fe(III) in single and binary systems onto pretreated orange peel

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