Optical and EPR spectroscopic studies of demetallation of hemin by L-chain apoferritins

Carette, Noëlle; Hagen, Wilfred R.; Bertrand, Luc; Val, Natalia de; Vertommen, Didier; Roland, Francine; Hue, Louis; Crichton, Robert R.

doi:10.1016/j.jinorgbio.2006.03.015

Cited by 14 publications

(6 citation statements)

References 40 publications

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“…The fact that demetallation of methemoglobin occurs in particular at pH 5.5 and in the presence of phosphate is consistent with observations in TiO 2 -cellulose films [39] and has been highlighted previously for a related process in ferritin [40]. However, further experimental work will be required to further resolve the fate of methemoglobin in SnO 2 -PDDAC films and the effect of the reaction conditions (pH, ionic strength, electrolyte composition, etc.).…”

Section: Attempted Immobilization and Reactivity Of Methemoglobin In supporting

confidence: 86%

SnO2–poly(diallyldimethylammonium chloride) films: Electrochemical evidence for heme protein absorption, denaturation, and demetallation

Milsom¹,

Dash²,

Jenkins³

et al. 2007

Journal of Electroanalytical Chemistry

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Section: Attempted Immobilization and Reactivity Of Methemoglobin In supporting

confidence: 86%

SnO2–poly(diallyldimethylammonium chloride) films: Electrochemical evidence for heme protein absorption, denaturation, and demetallation

Milsom¹,

Dash²,

Jenkins³

et al. 2007

Journal of Electroanalytical Chemistry

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“…We exclude the possibility that this signal is due to sample environment contamination since it was absent when either the empty cavity or a test tube containing the fixating solution were studied. The signal can be ascribed to the m s = ±3/2 Kramers doublet of rhombic S = 5/2 systems and it is not fully understood 59 . This iron form has taken different names in the literature, including mono-nuclear “spurious” iron, labile iron, iron bound to complexes of low molecular weight, and non-transferrin bound iron (NTBI) 1 , 60 .…”

Section: Discussionmentioning

confidence: 99%

Quantitative comparison of different iron forms in the temporal cortex of Alzheimer patients and control subjects

Bulk

Weerd

Breimer

et al. 2018

Sci Rep

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We present a quantitative study of different molecular iron forms found in the temporal cortex of Alzheimer (AD) patients. Applying the methodology we developed in our previous work, we quantify the concentrations of non-heme Fe(III) by Electron Paramagnetic Resonance (EPR), magnetite/maghemite and ferrihydrite by SQUID magnetometry, together with the MRI transverse relaxation rate , to obtain a systematic view of molecular iron in the temporal cortex. Significantly higher values of , a larger concentration of ferrihydrite, and a larger magnetic moment of magnetite/maghemite particles are found in the brain of AD patients. Moreover, we found correlations between the concentration of the iron detected by EPR, the concentration of the ferrihydrite mineral and the average iron loading of ferritin. We discuss these findings in the framework of iron dis-homeostasis, which has been proposed to occur in the brain of AD patients.

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“…[ 34 ] Prior to this study the only known enzyme catalyzing heme demetallation is apoferritin, a globular protein complex that binds and stores iron. [ 35‐36 ] The apoferritin‐mediated demetallation process is achieved by a cluster of Glu residues, and the reaction is reversible and is expedited at low pH. Although the detailed mechanism for this demetallation is unclear, it was proposed the reaction involves redox chemistry that is coupled with protonation of the heme tetrapyrrole nitrogen.…”

Section: Resultsmentioning

confidence: 99%

“…Although the detailed mechanism for this demetallation is unclear, it was proposed the reaction involves redox chemistry that is coupled with protonation of the heme tetrapyrrole nitrogen. [ 35‐36 ] The newly identified demetallation reaction of ChuW is an unprecedented activity of radical SAM enzymes.…”

Section: Resultsmentioning

confidence: 99%

Radical SAM‐Dependent Demetallation of Heme

2022

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Demetallation of heme to release iron is a chemical difficult reaction and is highly rare in biochemistry, with apoferritin as the only known enzyme responsible for this process. Here we show the heme degradation enzyme ChuW catalyzes heme demetallation besides its known methyltransferase activity (which converts heme to a ring-open product anaerobilin). We show the demetallation activity of ChuW is radical SAM-dependent, and likely involves the same set of intermediates involved in the anaerobilin-producing pathway. The ChuW-catalyzed demetallation reaction does not require external reductant, and can occur on several heme analogs with different metal centers. These findings establish a brand-new chemistry in the radical SAM enzymes, highlighting the remarkable catalytic diversity of this superfamily of enzymes.

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Optical and EPR spectroscopic studies of demetallation of hemin by L-chain apoferritins

Cited by 14 publications

References 40 publications

SnO2–poly(diallyldimethylammonium chloride) films: Electrochemical evidence for heme protein absorption, denaturation, and demetallation

SnO2–poly(diallyldimethylammonium chloride) films: Electrochemical evidence for heme protein absorption, denaturation, and demetallation

Quantitative comparison of different iron forms in the temporal cortex of Alzheimer patients and control subjects

Radical SAM‐Dependent Demetallation of Heme

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