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

Iron deficiency affects more than one billion people worldwide, although it is most common among young children and women of childbearing age. Poor iron status has severe nutritional and health consequences. The authors describe the longitudinal effect of iron-fortified drinking water given to a group of Brazilian preschool children as a way of combatting iron deficiency and anemia. The statuses of 31 preschool children attending a day-care institution for low socioeconomic families in Ribeirao Preto were followed from November 1990 to October 1991. Iron sulfate was added daily to subjects' drinking water container. Measurements of hemoglobin and serum ferritin levels in the children were taken before the addition and four and eight months later to evaluate iron status. Mean hemoglobin values increased from 10.6 to 13.7 g/dL and serum ferritin from 13.7 to 25.6 ug/L with no problems reported related to the salt addition or to the children drinking the iron-enriched water. The number of iron-deficient children decreased drastically after they began drinking the iron-enriched water. It may therefore be concluded that iron-enriched drinking water is a practical alternative to supply iron to children attending a day-care institution.
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PMID:Drinking water as an iron carrier to control anemia in preschool children in a day-care center. 800 2

Ferritin is a 24 subunit protein that controls biomineralization of iron in animals, bacteria, and plants. Rates of mineralization vary among members of the ferritin family, particularly between L and H type subunits of animal ferritins which are differentially expressed in various cell types. To examine ferritin from a highly differentiated cell type and to clarify the relationship between ferritin structure and function, bullfrog red cell L ferritin has been cloned, overexpressed in E. coli, and crystallized under two conditions. Crystals were obtained at high ionic strength in the presence of MnCl2 at a concentration comparable to that of the protein and in the presence of MgCl2 at a concentration much higher than that of the protein. Under both crystallization conditions, the crystals are tetragonal bipyramids in the space group F432 with unit cell dimensions a = b = c = 182 +/- 0.5 A. Crystals obtained in the presence of manganese and ammonium sulfate diffract to 1.9 A, while those obtained in the presence of magnesium and sodium tartrate diffract to 1.6 A. Isomorphous crystals have been obtained under similar conditions for a site-directed mutant with a reduced mineralization rate in which Glu-57, -58, -59, and -61 are all replaced by Ala. The structure of wild type L-subunit with magnesium has been solved by molecular replacement using the calcium salt of human liver H subunit (Lawson et al., Nature (London) 349:541-544, 1991) as the model. The crystallographic R factor for the 6-2.2 A shell is 0.21. The overall fold of human H and bullfrog L ferritins is similar with an rms difference in backbone atomic positions of 0.97 A. The largest structural differences occur in the D helix and the loop connecting the D and E helices of the four helix bundle. Because red cell L ferritin and liver H ferritin show differences in both rates of mineralization and three-dimensional structure, more detailed comparisons of these structures are likely to shed new light on the relationship between conformation and function.
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PMID:Crystallization and structural analysis of bullfrog red cell L-subunit ferritins. 815 61

Absolute iron deficiency is treated by correcting the causative lesion and then, traditionally, administering sufficient amounts of ferrous salt to return the haemoglobin level to normal and replenish body stores. The bioavailability of ferric compounds has been questioned and accordingly their therapeutic role remains controversial. A special problem is posed by regular blood donation, where the frequency of phlebotomy is limited by the haemoglobin level, which, in turn, requires maintenance of an adequate supply of iron from dietary sources. Since this latter situation may not always occur, it would be of practical benefit to have a form of supplementation that is effective and can be taken without side effects. These issues were prospectively examined in a consecutive series of otherwise healthy blood donors who developed absolute iron deficiency anaemia and were then randomly allocated to receive 60 mg of this metal as ferrous sulphate twice a day (Group 1: n = 51), 100 mg as chewable ferric polymaltose daily (Group 2: n = 53), or the latter product twice a day (Group 3: n = 55). Serial studies showed that 80% of patients in Groups 1 and 3 had reached normal haemoglobin levels by 12 weeks, but this figure was only 50% in Group 2. Similarly, the proportion of patients improving their percentage saturation of transferrin to within the normal range was significantly better in Groups 1 and 3 than in Group 2 (P < .01). However, body iron stores, reflected in serum ferritin level, was significantly better in Group 1 (P < .01); there was no difference in this respect between Groups 2 and 3.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparative bioavailability of ferric polymaltose and ferrous sulphate in iron-deficient blood donors. 822 11

Twenty-eight strict vegetarians were given 500 mg ascorbic acid twice daily after lunch and dinner for two months. Hemoglobin and certain iron status parameters were measured before and after the treatment. Ascorbate treatment increased mean hemoglobin by 8%, serum iron by 17% and transferrin saturation by 23% and decreased total iron binding capacity by 7%. All these changes were statistically significant. The rise in serum ferritin was 12%. The serum protein or copper level did not indicate their dietary deficiency, while initial serum ascorbate level were low which rose by 60% on therapy. It is concluded that ascorbate supplementation is a better method of improving hematologic and iron status than iron salt administration.
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PMID:Correction of anemia and iron deficiency in vegetarians by administration of ascorbic acid. 858 55

Caco-2 cells in culture provide an attractive model for the study of human iron absorption. Because iron status has a marked effect on human iron absorption, we devised serum-free growth conditions that allow manipulation of Caco-2 cell iron stores while maintaining growth. Caco-2 cells were cultured in serum-free media containing 0-20 micromol/L added iron. Intracellular ferritin, measured by radioimmunoassay, increased 100-fold with the addition of 20 micromol/L iron to the serum-free growth medium. Iron uptake and transfer across Caco-2 cell monolayers were measured from balanced salt solutions of ferrous and ferric forms of iron. Uptake from ferrous, but not ferric, iron was inversely related to cell ferritin concentration and culture medium iron concentration. Kinetic analysis of uptake data from solutions of ferrous and ferric iron revealed saturable and nonsaturable components for ferrous iron, but only a nonsaturable component for ferric iron. Uptake by the nonsaturable pathway was not affected by cell ferritin concentration for either form of iron. Maximal uptake from a ferrous iron solution via the saturable pathway was nearly 100% greater in cells cultured under low compared with high iron conditions. Iron transfer across Caco-2 monolayers was not proportional to iron uptake, but was related to monolayer permeability. Iron uptake by Caco-2 cells was a reliable indicator of relative iron availability. We observed no difference in iron transfer that was related to the iron status of the cell monolayer. The lack of this effect suggests that this model may be inadequate for studies of iron transfer.
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PMID:Ferrous iron uptake but not transfer is down-regulated in Caco-2 cells grown in high iron serum-free medium. 900 82

Contribution of electrostatic interactions to stability of BPTI orthorhombic, pig-insulin cubic crystals, and horse L ferritin crystals was evaluated with numerical calculation of Poisson-Boltzmann equation based on a dielectric model. The stability of a ferritin molecule (24-mer) composed of 24 subunits was also evaluated. It was found that the surface charge-charge interactions at separation distances (< 5 A) were insensitive to variations in the ionic strength, and thus stabilized assembled states of the proteins (i.e., crystalline state and oligomeric state). It was also revealed that the charge density and the packing of the protein crystals were largely responsible for the ionic strength dependence of the crystal stability. The stability of the 5PTI crystalline state with a high charge density drastically increased as the concentration of the solvent ions increased. In contrast, that of the insulin crystal with a low charge density and large solvent region was insensitive to changes in the ionic concentration. The electrostatic interaction between ferritin 24-mers was attributed to two salt bridges mediated by Cd ion. For the stability of the ferritin 24-mer, which is evolutionally designed, the electrostatic stabilization between the subunits was attributed to polar bonds such as buried salt bridges or hydrogen bonds, which occasionally yielded more than 5 kcal/mol and were numerous and very strong compared with the bonds between molecules in the 5PTI and 9INS crystals. By analyzing the atomic charge-charge interactions in detail, it was found that charge pairs separated by less than 3 A, such as hydrogen bonds, dominantly stabilize the assembled states, and that pairs 3 to 5 A apart were also important. The stability of the assembled states evaluated by the total EET was determined by the fine balance between the two competing contributions arising from the stabilizing atoms and the destabilizing atoms. Changes of the ASA and hydration free energy were also evaluated in accordance with the process of the subunit assembly. The change of hydration free energy, which was very large (i.e., approximately +100 kcal/mol/subunit) and unfavorable for the assembly, was proportional to the electrostatic hydration energy (i.e., Born energy change in the hydration process). Hydrophobic groups were likely to appear more frequently than hydrophilic groups at the interfaces. This study offers a method which can improve the stability of protein crystals by introducing polar or charged residues that are properly designed to form specific hydrogen bonds or salt bridges between neighboring protein molecules. This method is also applicable to crystallography, because it improves refinement of protein structures in crystals by taking the inter-protein interactions into account.
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PMID:Significant role of electrostatic interactions for stabilization of protein assemblies. 920 25

The interactions between iron and neuromelanin (NM) have been studied by means of EPR spectroscopy. The variable temperature EPR spectral features of a specimen of NM extracted from normal human midbrains clearly indicate that iron is present as polynuclear oxy-hydroxy ferric aggregates as well as isolated Fe(III) centres. Ferric oxy-hydroxy phases are typical of the iron storage proteins ferritin and hemosiderin, but the comparison of the variable temperature EPR spectra of ferritin and NM highlights significant differences between the two iron(III)oxy-hydroxy domains. Moreover, further investigations on melanin models synthesised in the presence of either ferritin or a ferric salt as iron sources suggest that the same pathway of formation and inclusion of the polynuclear iron oxide is operating in NM and in the model systems, whatever is the source of iron.
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PMID:EPR investigations of the iron domain in neuromelanin. 924 89

We previously reported that the heavy chain of ferritin was required for loading it with iron using ceruloplasmin as a ferroxidase [J.-H. Guo, M. Abedi, and S. D. Aust (1996) Arch. Biochem. Biophys. 335, 197-204]. Site-directed mutagenesis, K58E and G61H, on recombinant rat liver L chain ferritin (rL-Ft) was performed to construct a proposed iron-loading channel in the alpha-helix bundle similar to rat liver H chain ferritin (rH-Ft). Conversely, the channel in rH-Ft was closed by mutations E62K and H65G to form a K62 to E107 salt bridge, which is believed to exist in the L chain. Both variants were expressed in insect cells and were soluble and able to form multi-subunit homopolymers. The rH-Ft mutant homopolymer could not be loaded, whereas the rL-Ft mutant homopolymer could be loaded with iron by ceruloplasmin. However, we found that the initial rate of iron loading into the rL-Ft mutant homopolymer by ceruloplasmin was less than that into the rH-Ft homopolymer. When 500 atoms of iron per ferritin were used for loading, 98% was loaded into the rH-Ft homopolymer by ceruloplasmin in 15 min, but only 30% was loaded into the rL-Ft mutant homopolymer in the same time. Moreover, the ferroxidase activity of ceruloplasmin was enhanced in the presence of the rH-Ft and the rH-Ft mutant homopolymers, but not in the presence of the rL-Ft or the rL-Ft mutant homopolymers. These observations suggested that the four alpha-helix bundle channel of ferritin is required for iron loading, but an additional factor, i.e. , a site which stimulate the ferroxidase activity of ceruloplasmin, is also essential.
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PMID:Mutational analysis of the four alpha-helix bundle iron-loading channel of rat liver ferritin. 952 17

Thermodynamic and pH stability of recombinant human L- and H-ferritins were probed by differential scanning calorimetry and 8-anilino-1-naphthalenesulfonate (ANS) binding in the pH range 2-7. At pH 2.0-2.8 they were dissociated into subunit monomers and in this pH interval the H-subunit displayed a single calorimetrically-revealed domain with properties of a molten globule-like state: low enthalpy (6.3-8.0 J/g or 169-172 kJ/mol) and Tm of thermal unfolding (approximately 50 degrees C), a wide transition range (approximately 20 degrees C) and high ANS binding. In contrast, at pH 2 the L-ferritin subunit showed two calorimetric domains with Tm of 35 and 40 degrees C with similar unfolding enthalpies and with moderate extent of interactions, as indicated by the ratio of calorimetric enthalpy (293.9 kJ/mol) and van't Hoff enthalpy (174.2 kJ/mol) for the thermal transition. A pH increase from 2.0 to 2.8 determined the coupling of the two domains into a single cooperative folding unit and drastic increase of the transition temperature (from 37 to 80 degrees C). The contacts between the two domains in the L-subunit appeared to contribute to about 30% of the total stabilization free energy. The unfolding enthalpies, heat capacity changes and pronounced ANS binding of the L-subunit at pH 2.0-2.8 indicated that part of the structure lacked 'meltable' tertiary interactions. The results indicate that H- and L-subunits are stabilized by largely different intra-chain interactions with a critical contribution to L-subunit stability of embedded salt bridge(s) absent in the H-subunit.
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PMID:Distinct stability of recombinant L and H subunits of human ferritin: calorimetric and ANS binding studies. 968 70

To improve the health and nutritional status of school children in an area of iodine deficiency disorders (IDD) by means of different iodine fortifications in salt, fish sauce and drinking water, anthropometric assessment for nutritional measurement, including hematological status, were performed. There was a significant difference in the weight and height of the children from the four schools investigated, before and after supplementation in each school. The prevalence of anemia (as indicated by hematological measurement) and iodine deficiency (as indicated by urinary iodine concentration in the children from the four schools) were assessed and compared before and after iodine supplementation; a decrease in prevalence was found in all school children, however, serum ferritin did not change before and after supplementation.
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PMID:Nutritional status of school children in an endemic area of iodine deficiency disorders (IDD) after one year of iodine supplementation. 974 Feb 68


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