Characterization of ferritin from human placenta

Lavoie, Daniel J.; Marcus, Donald M.; Otsuka, Soichi; Listowsky, Irving

doi:10.1016/0005-2795(79)90063-1

Cited by 31 publications

(9 citation statements)

References 34 publications

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“…Sensitivity of ferritinpore function to conservative amino acid changes suggested that the ferritin pores would also be differentially sensitive to solvent molecules that unfold proteins, such as urea (12). We now show that in ferritin, although the global structure is stable to 6 M urea at neutral pH (13,14) and temperatures up to 85°C (15), ferritin pores are opened by low chaotrope concentrations (1.0 mM to 1 M urea or guanidine), assessed as Fe 2ϩ -chelation rates. Moreover, a melting transition (53°C) of a helix subdomain that we observed in ferritin by CD spectroscopy was downshifted 10°C by 1 mM urea, in parallel with the increased rate of Fe 2ϩ chelation, indicating a relationship between the helix subdomain and the pores.…”

mentioning

confidence: 82%

“…(Right) The absence of pore structure is illustrated as the black or empty area, which was made from Left and the data in ref. 3. urea concentrations as high as 6-10 M (13, 14, 25), we investigated effects on pore gating as the formation of Fe 2ϩ -bipyridyl in the presence of NADH͞FMN by using mineralized ferritins with millimolar concentrations of urea that would not affect global ferritin structure (13,14). Both 1 and 10 mM urea increased rates of Fe 2ϩ chelation significantly (Fig.…”

Section: Effects Of Chaotropes Detergent and Nacl On Chelation Of Fmentioning

confidence: 99%

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Opening protein pores with chaotropes enhances Fe reduction and chelation of Fe from the ferritin biomineral

Liu¹,

Jin²,

Theil³

2003

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

189

243

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Iron is concentrated in ferritin, a spherical protein with a capacious cavity for ferric nanominerals of <4,500 Fe atoms. Global ferritin structure is very stable, resisting 6 M urea and heat (85°C) at neutral pH. Eight pores, each formed by six helices from 3 of the 24 polypeptide subunits, restrict mineral access to reductant, protons, or chelators. Protein-directed transport of Fe and aqueous Fe 3؉ chemistry (solubility Ϸ10 ؊18 M) drive mineralization. Ferritin pores are ''gated'' based on protein crystals and Fe chelation rates of wild-type (WT) and engineered proteins. Pore structure and gate residues, which are highly conserved, thus should be sensitive to environmental changes such as low concentrations of chaotropes. We now demonstrate that urea or guanidine (1-10 mM), far below concentrations for global unfolding, induced multiphasic rate increases in Fe 2؉ -bipyridyl formation similar to conservative substitutions of pore residues. Urea (1 M) or the nonconservative Leu͞Pro substitution that fully unfolded pores without urea both induced monophasic rate increases in Fe 2؉ chelation rates, indicating unrestricted access between mineral and reductant͞chelator. The observation of low-melting ferritin subdomains by CD spectroscopy (melting midpoint 53°C), accounting for 10% of ferritin ␣-helices, is unprecedented. The low-melting ferritin subdomains are pores, based on percentage helix and destabilization by either very dilute urea solutions (1 mM) or Leu͞Pro substitution, which both increased Fe 2؉ chelation. Biological molecules may have evolved to control gating of ferritin pores in response to cell iron need and, if mimicked by designer drugs, could impact chelation therapies in iron-overload diseases.

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mentioning

confidence: 82%

Section: Effects Of Chaotropes Detergent and Nacl On Chelation Of Fmentioning

confidence: 99%

Opening protein pores with chaotropes enhances Fe reduction and chelation of Fe from the ferritin biomineral

Liu¹,

Jin²,

Theil³

2003

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

189

243

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“…This effect is mediated by progesterone (55). In addition, the serum level of human placental isoferritin, which consists of LCF and a super heavy chain ferritin (p43) usually present in low levels, rises sharply from the start of pregnancy until the end of pregnancy (67) and is present in placental and fetal tissues (68,69). The increased expression of p43 and HCF and the increased catabolism observed during pregnancy in the rat model suggest a means by which catabolism may be modulated in vivo.…”

Section: Discussionmentioning

confidence: 99%

Purification and Properties of a Folate-catabolizing Enzyme

Suh

Oppenheim

Girgis

et al. 2000

Journal of Biological Chemistry

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We have identified and purified to homogeneity an enzyme from rat liver that catalyzes the oxidative catabolism of 5-formyltetrahydrofolate to p-aminobenzoylglutamate and a pterin derivative. Purification of the enzyme utilized six column matrices, including a pterin-6-carboxylic acid affinity column. Treatment of crude rat liver extracts with EDTA or heat decreased the specific activity of the enzyme by up to 85%. Peptides generated from the purified protein were sequenced and found to be identical to primary sequences present within rat light chain or heavy chain ferritin. Commercial rat ferritin did not display catabolic activity, but activity could be acquired with iron loading. The purified enzyme contained 2000 atoms of iron/ferritin 24-mer and displayed similar electrophoretic properties as commercial rat liver ferritin. The ferritin-catalyzed reaction displayed burst kinetics, and the enzyme catalyzed only a single turnover in vitro. Expression of rat heavy chain ferritin cDNA resulted in increased rates of folate turnover in cultured Chinese hamster ovary cells and human mammary carcinoma cells and reduced intracellular folate concentrations in Chinese hamster ovary cells. These results indicate that ferritin catalyzes folate turnover in vitro and in vivo and may be an important factor in regulating intracellular folate concentrations.

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“…The iron-storage protein, ferritin, consists of 24 protein subunits assembled round an iron-core of ferrihydrite (Clegg et al, 1980;Theil, 1983). When subjected to isoelectric focusing, ferritin focuses over a relatively wide pH range, giving several bands, or isoferritins (Arosio et al, 1978;Lavoie et al, 1978;Russell & Harrison, 1978;Wagstaff et al, 1978). On sodium dodecyl sulphate/polyacrylamide-gel electrophoresis most ferritins separate into two subunits bands, known as H and L (heavy and light respectively).…”

mentioning

confidence: 99%

“…The relative proportions of H and L subunits vary with tissue of origin and across the pH profile (Arosio et al, 1978;Bomford et al, 1981). Two-dimensional separation, combining isoelectric focusing with subsequent sodium dodecyl sulphate/polyacrylamide-gel electrophoresis (O'Farrell, 1975), indicates further sub-division of the H and L subunits (Arosio et al, 1978;Lavoie et al, 1978;Watanabe & Drysdale, 1981). Although the observed subunit heterogeneity might be explained by differences in primary structure (Adelman et al, 1975), it is only relatively recently that evidence has been found for the presence of more than one amino acid sequence in ferritin preparations from human (Wustefeld & Crichton, 1982;Addison et al, 1983;Costanzo et al, 1984), horse (Heusterspreute & Crichton, 1981) and rat (H. N. Munro, personal communication).…”

mentioning

confidence: 99%

Iron-induced changes in rat liver isoferritins

Treffry¹,

Lee²,

Harrison³

1984

Biochemical Journal

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The effects of single and of multiple iron injection on the distribution of isoferritins was studied in rat liver with the aid of 14C-labelling either after or before iron treatment. Several effects of iron can be seen. Analysis of protein and labelling patterns show that it not only produces a disproportionate increase in the more-basic isoferritins, but may, in sufficient dose, actually lead to a decrease in the more-acidic isoferritins. Use of iron injection after radioactivity shows that it must give rise to post-assembly changes causing acidic isoferritins to become more basic. With a moderate iron dose this change is relatively slow, taking several hours, and seems to occur in addition to a differential stimulation of the synthesis of the more-basic isoferritins. With higher iron dosage the post-assembly changes may be so rapid that it is difficult to distinguish them from a switch in the pattern of synthesis.

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Characterization of ferritin from human placenta

Cited by 31 publications

References 34 publications

Opening protein pores with chaotropes enhances Fe reduction and chelation of Fe from the ferritin biomineral

Opening protein pores with chaotropes enhances Fe reduction and chelation of Fe from the ferritin biomineral

Purification and Properties of a Folate-catabolizing Enzyme

Iron-induced changes in rat liver isoferritins

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