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Iron protein transport

Hemoproteins which engage in electron transport — the cytochromes — are much more widely dispersed among living species and occur in microorganisms, plants and animals (13). Again there are two types of iron proteins which can perform the task of electron transport, the heme and the non-heme. The latter term has become practically synonymous... [Pg.149]

Figure 8.7 Simplified model of nicotiniamine (NA) function in plant cells. Iron is transported across the plasma membrane by the Strategy I or Strategy II uptake systems. Once inside the cell, NA is the default chelator of iron to avoid precipitation and catalysis of radical oxygen species. The iron is then donated to proteins, iron-sulfur clusters and haem, while ferritin and iron precipitation are only present during iron excess. (From Hell and Stephan, 2003. With kind permission of Springer Science and Business Media.)... Figure 8.7 Simplified model of nicotiniamine (NA) function in plant cells. Iron is transported across the plasma membrane by the Strategy I or Strategy II uptake systems. Once inside the cell, NA is the default chelator of iron to avoid precipitation and catalysis of radical oxygen species. The iron is then donated to proteins, iron-sulfur clusters and haem, while ferritin and iron precipitation are only present during iron excess. (From Hell and Stephan, 2003. With kind permission of Springer Science and Business Media.)...
Under normal physiological conditions, iron is transported in serum by transferrin, an 80 kDa bilobal protein with two almost identical iron-binding sites, one in each half of the molecule. [Pg.144]

Iron (Fe) is quantitatively the most important trace element (see p. 362). The human body contains 4-5 g iron, which is almost exclusively present in protein-bound form. Approximately three-quarters of the total amount is found in heme proteins (see pp. 106,192), mainly hemoglobin and myoglobin. About 1% of the iron is bound in iron-sulfur clusters (see p. 106), which function as cofactors in the respiratory chain, in photosynthesis, and in other redox chains. The remainder consists of iron in transport and storage proteins (transferrin, ferritin see B). [Pg.286]

Additional binuclear octahedral iron proteins have been identified. Of these the purple acid phosphatase has been the most vigorously studied and has a distinctly different biochemical function. Indeed, the protein may be involved with iron transport as well as a hydrolase (Doi et aL, 1988 Nuttleman and Roberts, 1990). Because there are insufficient structural data to provide a basis of comparison, we have omitted it from our discussion. Likewise, rubrerythrin has only recendy been identified as a member of the class, and no enzymology has been established (LeGall et al., 1988) thus, its inclusion in this discussion would be premature. There... [Pg.239]

Iron is transported via transferrin. When body stores of iron are high, ferric iron combines with apoferritin to form ferritin. Ferritin is the protein of iron storage. About 80 percent iron in plasma goes to erythroid marrow. The excretion of iron is minimal. Only little amount of iron is lost by exfoliation of intestinal mucosal cells and trace amount is excreted in urine, sweat and bile. [Pg.248]

A few substances are so large or impermeant that they can enter cells only by endocytosis, the process by which the substance is bound at a cell-surface receptor, engulfed by the cell membrane, and carried into the cell by pinching off of the newly formed vesicle inside the membrane. The substance can then be released inside the cytosol by breakdown of the vesicle membrane. Figure 1-5D. This process is responsible for the transport of vitamin B12, complexed with a binding protein (intrinsic factor) across the wall of the gut into the blood. Similarly, iron is transported into hemoglobin-synthesizing red blood cell precursors in association with the protein transferrin. Specific receptors for the transport proteins must be present for this process to work. [Pg.23]

The functions of the heme is uncertain. The soluble mammalian succinate dehydrogenase resembles closely that of E. coli and contains three Fe-S centers binuclear SI of E° 0 V, and tetranuclear S2 and S3 of -0.25 to -0.40 and + 0.065 V, respectively. Center S3 appears to operate between the -2 and -1 states of Eq. 16-17 just as does the cluster in the Chromatium high potential iron protein. The function of the very low potential S2 is not certain, but the following sequence of electron transport involving SI and S3 and the bound ubiquinone QD-S66 has been proposed (Eq. 18-4). [Pg.1027]

Mitochondrial Myopathy. A general deticiency of iron may ho implicated in mitochondrial myopathy, which is a complex disorder that affects muscular activity. It lias been suspected for a number of years that the disorder is caused hy a delect of mitochondrial-protein transport. H.H.V. Sdiarpa and a team of researchers (Royal Free Hospital. London) postulate that a deficiency of an iron-sulfur protein in muscle dehydrogenase may be the specific cause. [Pg.876]

As noted earlier, nitrogenase is made up of two proteins, the iron protein, and the molybdenum-iron protein, and will be linked to an electron-transport chain. The iron protein accepts electrons from this chain (a ferredoxin or flavodoxin in vivo, or dithionite in vitro) and transfers them to the molybdenum-iron protein. The MoFe protein is then able to reduce a number of substrates in addition to dinitrogen. No replacement electron donor will function instead of the iron protein. [Pg.719]


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See also in sourсe #XX -- [ Pg.81 , Pg.93 , Pg.99 ]




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Electron transport chain iron-sulfur proteins

Electron transport iron-containing proteins

Iron protein electron transport

Iron protein proteins

Iron storage and transport proteins

Iron transport

Iron transporters

Transport proteins

Transporter proteins

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