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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe the development and evaluation of a serum ferritin radioimmunoassay, in which 125l-labeled ferritin and rabbit anti-ferritin antibody are used. Goat anti-rabbit gamma-globulin antibody, together with polyethylene glycol, is used as the separating reagent. The assay has a working range up to 500 mug of ferritin per litre, and a sample requirement of 75 mul of serum for assay at two dilutions. The assay requires 24 h. it has a sensitivity of 1.5 mug of ferritin per litre and a long-term precision (CV) of 13%. Reference intervals for a population of men were 18-330 mug/litre, with no marked age dependence, while those for a population of women older than 50 years were 18-200 mug/litre. Many apparently healthy women in the 20-50 year age group have much lower concentrations. Serum ferritin concentrations of less than 18 mug/litre are indicative of iron deficiency, defined as the absence of stainable iron in an aspirate of bone marrow.
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PMID:A radioimmunoassay for serum ferritin. 55 79

The time dependence of agglutination and cell-cell contact spreading in human erythrocytes exposed to wheat germ agglutinin (WGA) was characterized by light and electron microscopy. Cells (3 x 10(7)/mL) had a threshold lectin concentration in the range of 0.6-2.0 micrograms/mL for initial cell contact. Spreading was essentially completed within 60 and 2 min in undisturbed and gently agitated suspensions, respectively. The cells in large WGA agglutinates retained features of their initial disk form in contrast to the convex outlines of polycation or polyethylene glycol-induced agglutinates. Spreading of contact area was accompanied by development of a pattern of discrete contact regions separated by a distance of the order of 1 micron. Freeze fracture electron microscopy and studies with ferritin-labeled WGA showed no significant aggregation of intramembrane particles or specific lectin receptors under conditions when contact spreading occurred. It is argued that flow stress effects on cells in suspended agglutinates give rise to a situation where opposite membranes, at the leading edge of cell contact, are separated by a thin aqueous layer. When this intercellular water layer exceeds a critical length, it becomes unstable. The layer breaks up by surface wave development to form an array of intracellular water spaces. Formation of the aqueous spaces causes opposite membrane regions to move synchronously toward each other. Lectin molecules crosslink the wave crests to give spatially periodic contact points.
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PMID:Spreading of wheat germ agglutinin-induced erythrocyte contact by formation of spatially discrete contacts. 169 48

The in vitro selfassembly of apoferritin after previous dissociation and unfolding in 7.2M guanidinium chloride, pH 3.5, yields up to 80% of a protein complex exhibiting the molecular mass of the native icositetramer of greater than or equal to 450 kDa. After removal of high molecular mass byproducts, the final reassembly product proves to be indistinguishable from native apoferritin with respect to its functional and conformational properties. These refer to the intrinsic fluorescence and to the far and near UV circular dichroism. The unfolding transitions of the native and reassembled protein in aqueous guanidinium chloride or at acid pH coincide within the range of error. The reassembled protein is also able to catalyze the oxidation of Fe(II). Higher polymers of the apoferritin complex represent most of the residual 20% of the reconstituted protein. They are stabilized by non-covalent (preferentially hydrophobic) interactions, and may be disassembled to the icositetramer by preferential solvation of the protein in the presence of less than or equal to 50% (v/v) ethylene glycol. The change in fluorescence emission accompanying polymerization reflects altered surface properties of the apoferritin subunits compatible with those reported for the ferritin----hemosiderin transition.
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PMID:Assembly of apoferritin from horse spleen: comparison of the protein in its native and reassembled state. 360 23

An interaction between human and rabbit ferritins and serum was demonstrated by a coated tube binding assay, a shift in molecular size on gel filtration and by precipitation of complexes with 3.5% polyethylene glycol 6000. With polyethylene glycol and labelled ferritins, complex formation was inhibited by heating sera to 56 degrees C for 30 min and by addition of EDTA or excess unlabelled ferritins. Human heart ferritin showed the greatest interaction with serum, followed by human spleen ferritin and least of all human plasma ferritin. Ferritins did not appear to bind to IgG or IgM in normal sera. The interaction of 'H' subunit-containing ferritins with serum or plasma may be partly responsible for the rapid clearance of tissue ferritins from the circulation and the absence of acidic isoferritins in the plasma of normal subjects.
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PMID:Interaction of ferritin with serum: implications for ferritin turnover. 637 62

The blood of the winter flounder, Pseudopleuronectes americanus, contains small (3000-8000 daltons) anionic peptides (pI less than 5) with antifreeze properties. They are present only in the winter and are retained in the circulatory system even though inulin and polyethylene glycol, of comparable molecular size, are filtered by the glomerular kidney. Electron micrographs of flounder-kidney glomeruli revealed that their structure is similar to that of mammals and that cationized ferritin binds at regular 60 nm intervals in the lamina rara interna of the basement membrane as it does in mammals. The binding of cationized ferritin, in conjunction with the previous observation that cationized antifreeze peptides exhibit a marked increase in renal clearance, suggests that an anionic repulsion barrier within the glomerular basement membrane of the winter flounder is responsible for the conservation of the anionic antifreeze peptide molecules found in their blood during the winter. This barrier also appears to be present in summer specimens of the flounder which lack the antifreeze peptide.
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PMID:The seasonal distribution of anionic binding sites in the basement membrane of the kidney glomerulus of the winter flounder Pseudopleuronectes americanus. 664 Jun 23

A fluorescent enzyme-linked immunosorbent assay is described for the rapid measurement of serum ferritin. Increased sensitivity was achieved by using 4-methyl-umbelliferyl-beta-D-galactopyranoside as the substrate for beta-galactosidase coupled to the purified antiferritin antibody. Further enhancement of the specific antigen-antibody reaction was attained by the addition of 4% polyethylene glycol 6000 to the antiferritin-beta-galactosidase conjugate. The procedure is performed in microELISA plates. These modifications of the method permit the measurement of serum ferritin at concentrations ranging from 0.25 to 50 microgram/liter with a coefficient of variation of 8% or less. The entire procedure is performed at ambient temperature and is completed within one working day. The cost of the assay is less than 10% of the immunoradiometric assay for serum ferritin.
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PMID:A rapid and sensitive ELISA for serum ferritin employing a fluorogenic substrate. 681 55

Various precipitating agents were examined in order to crystallize horse heart and spleen ferritins. Cadmium sulfate induced the crystallization of the spleen ferritin, while 2-methyl-2,4-pentanediol and poly(ethylene glycol) only induced that of the heart ferritin. Isoelectric focusing analysis showed that the crystals grown from cadmium sulfate contained only the more acidic isoferritins, and those grown from methyl pentanediol only the less acidic isoferritins. Heart ferritin crystallizes in a cubic space group, as previously reported for spleen ferritin crystals grown from cadmium sulfate.
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PMID:Selective crystallization of horse isoferritins. 683 99

We describe a solid-phase enzyme immunoassay for human serum ferritin, with the use of polyethylene glycol to shorten the reaction. The amount of bound enzyme-antibody conjugate used as a second site antibody is proportional to the ferritin titre in the assay. This method is fast, and the reagents are stable for many months at 4 degrees C. The lowest detectable concentration was 5 micrograms/l. Interassay coefficients of variation were 9.3 and 12.2%, respectively, at ferritin concentrations of 100 micrograms/l and 200 micrograms/l. The data also show that polyethylene glycol accelerates antigen-antibody complex formation in the solid phase. An assay may be completed in 5 h.
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PMID:Solid phase ELISA for serum ferritin. 700 76

Urinary recovery of intratracheally instilled polyethylene glycol polymers (PEG:s) in the molecular weight range 722-1294 Da (PEG 1000) was studied under normal conditions and during experimentally induced lung damage in rats. The urinary PEG recoveries were between 30-60% under normal conditions, with a selectivity for smaller PEG:s. No significant differences in the urinary PEG molecular weight profiles were found between 30 days old and adult rats; i.e. they had similar PEG 1162/810 (molecular weights) urinary recovery ratios (0.78 +/- 0.25 and 0.69 +/- 0.27, respectively, p > 0.05). In rats instilled with PEG 1000 and ferritin (5 mg.kg-1 body weight), the urinary recovery was increased for PEG:s with molecular weights greater than 1030 Da; i.e. a higher PEG 1162/810 recovery ratio (1.44 +/- 0.58, p < 0.01) was obtained. Rats instilled with PEG 1000 and crocidolite asbestos fibres (5 mg.kg-1 body weight) showed higher urinary recoveries for PEG:s greater than 854 Da, resulting in a higher PEG 1162/810 ratio (1.47 +/- 0.59, p < 0.01). By adding the iron-chelator, desferrioxamine, to the crocidolite-instillate, the urinary recoveries and the PEG 1162/810 ratio (0.97 +/- 0.47) were reduced, indicating a restored molecular weight selectivity of the lung. Thus, in rats, PEG 1000 passes via the respiratory tract in large amounts which is dependent on the molecular weight. This passage was increased after ferritin- or crocidolite instillation, indicating that the barrier function of the respiratory tract was impaired due to local tissue damage, and that iron may play an important role in this.
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PMID:Increased lung to blood passage of polyethylene glycols after intratracheal instillation of ferritin and asbestos fibres in the rat. 838 Oct 92

This study describes the application of aqueous two-phase partition using polyethylene glycol (PEG)-potassium phosphate systems for the direct recovery of proteins, and aggregates thereof, from mammalian brain tissue homogenates. Investigation of established methodologies for the purification of prion proteins (PrP) from bovine brain affected with transmissible spongiform encephalopathy (BSE) has identified an alternative purification regime based on aqueous two-phase partition. This circumvents energy-intensive and rate-limiting unit operations of ultracentrifugation conventionally used for isolation of PrP. Selectivity of various PEG-phosphate systems varied inversely with polymer molecular mass. The maximum protein recovery from bovine brain extracts was obtained with systems containing PEG 300. Manipulation of the aqueous environment, to back-extract protein product from the PEG-rich top phase into the phosphate-rich lower phase, enabled integration of ATPS with conventional hydrophobic interaction chromatography (HIC) which selectively removes obdurate contaminating proteins (i.e. ferritin).
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PMID:Aqueous two-phase partition of complex protein feedstocks derived from brain tissue homogenates. 879 85


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