Storage of iron

Hemosiderin is a somewhat ill-defined molecule it appears to be a pardy degraded form of ferritin but still containing iron. It can be detected by histologic stains (eg, Pmssian blue) for iron, and its presence is determined histologically when excessive storage of iron... 

Hereditary (primary) hemochromatosis is a very prevalent autosomal recessive disorder in certain parts of the world (eg, Scodand, Ireland, and North America). It is characterized by excessive storage of iron in tissues, leading to tissue damage. Total body iron ranges between 2.5 g and 3.5 g in normal adults in primary hemochromatosis it usually exceeds 15 g. The accumulated iron... 

HFE has been shown to be located in cells in the crypts of the small intestine, the site of iron absorption. There is evidence that it associates with P2 niicroglobu-lin, an association that may be necessary for its stability, intracellular processing, and cell surface expression. The complex interacts with the transferrin receptor (TfR) how this leads to excessive storage of iron when HFE is altered by mutation is under close smdy. The mouse homolog of HFE has been knocked out, resulting in a potentially useful animal model of hemochromatosis. 

Compartmentation means both spatial separation of potentially harmful but essential compounds (e.g., storage of iron in ferritin) and cell- and tissue-specific distribution of antioxidative compounds, and it serves to prevent uncontrolled oxidation. 

This loss is compensated by the alimentation. 70 % of the body iron is contained in hemoglobin. Transferrin ensures the transport of iron, while ferritin and hemosiderin are used for the storage of iron in a non-toxic form ferritin is indeed able to transform the highly toxic Fe(II) in to the less toxic Fe(III). 

Iron overload Unwarranted therapy with parenteral iron will cause excess storage of iron with the consequent possibility of exogenous hemosiderosis. 

Two proteins are important for iron metabolism in mammalian cells the transferrin receptor (TFR) md ferritin. Ferritin is a protein for the storage of iron. The production and its level is increased when more iron is available. 

Absorption, transport, and storage of iron. Intestinal epithelial cells actively absorb inorganic iron and heme iron (H). Ferrous iron that is absorbed or released from absorbed heme iron in the intestine (1) is actively transported into the blood or complexed with apoferritin (AF) and stored as ferritin (F). In the blood, iron is transported by transferrin (Tf) to erythroid precursors in the bone marrow for synthesis of hemoglobin (Hgb) (2) or to hepatocytes for storage as ferritin (3). The transferrin-iron complexes bind to transferrin receptors (TfR) in erythroid precursors and hepatocytes and are internalized. After release of the iron, the TfR-Tf complex is recycled to the plasma membrane and Tf is released. Macrophages that phagocytize senescent erythrocytes (RBC) reclaim the iron from the RBC hemoglobin and either export it or store it as ferritin (4). Hepatocytes use several mechanisms to... 

In addition to the storage of iron in intestinal mucosal cells, iron is also stored, primarily as ferritin, in macrophages in the liver, spleen, and bone, and in parenchymal liver cells (Figure 33-1). Apoferritin synthesis is regulated by the levels of free iron. When these levels are low, apoferritin synthesis is inhibited and the balance of iron binding shifts toward transferrin. When free iron levels are high, more apoferritin is produced to sequester more iron and protect organs from the toxic effects of excess free iron. 

There is no mechanism for excretion of iron. Small amounts are lost in the feces by exfoliation of intestinal mucosal cells, and trace amounts are excreted in bile, urine, and sweat. These losses account for no more than 1 mg of iron per day. Because the body s ability to excrete iron is so limited, regulation of iron balance must be achieved by changing intestinal absorption and storage of iron, in response to the body s needs. As noted below, impaired regulation of iron absorption leads to serious pathology. 

Apoferritin consists of a hollow, spherical shell of external diameter 125 A, which provides an inner cavity of maximum diameter about 80 A for the storage of iron. 

The possible role of the mycobactins in the storage of iron in the mycobacteria has been noted. Of greater significance is the identification of ferritin-like molecules in some bacteria. The cytochrome 6557.5 from Azotobacter vinelandii, known to be associated with large amounts of iron, is now known to be a ferritin, with an iron content of 13-20% and an electron-dense core of... 

Occasionally storage of iron has been proposed as a function of Fe/S proteins (cf. Chapter 8 in [4]). There are no recent reports on this possibility. 

Food source people must have an adequate supply of nutrient protein with the right balance of amino acids for adequate nutrition Storage of iron in animal tissues Structural and protective components in organisms Strong, fibrous proteins that can contract and cause movement to occur... 

The electron transferring non-heme iron proteins can be strictly differentiated from those non-heme iron proteins and polypeptides such as ferritin and ferrichrome which act in biological transfer and storage of iron. They can be distinguished also from iron-flavoproteins, such as succinic dehydrogenase, which contain flavin in addition to the iron constituent. Nevertheless, in many chemical and physical aspects, the non-heme iron moiety of the iron-flavoproteins exhibits behavior similar to that of electron-transferring non-heme iron proteins. 

Hepatocytes are involved in iron metabohsm in two ways they are the site of transferrin synthesis, and they represent the most important site in the storage of iron in the form of ferritin or haemosiderin. Hence the level of iron in the serum depends on the ability of the hepatocyte to store iron and to synthesize transferrin. (see chapters 3.11 and 31.17)... 

Microbial iron transport and infections in animals and plants The Storage of Iron in Microorganisms... 

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