Iron-protein complex

Henry, Y., Ducrocq, C., Drapier, J. C., Servent, D., Pellat, C., and Guissani, A. (1991). Nitric oxide, a biological effector. Electron paramagnetic resonance detection of nitrosyl-iron-protein complexes in whole cells. Eur. Biophys. J. 20, 1-15. 

Iron is stored in intestinal mucosal cells as ferritin (an iron/protein complex) until needed by the body. Iron deficiency results from acute or chronic blood loss, from insufficient intake during periods of accelerated growth in children, or in heavily menstruating or pregnant women. Therefore it essentially results from a negative iron balance due to depletion of iron stores and inadequate intake, culminating in hypochromic microcytic anemia. Supplementation with ferrous sulfate is required to correct the deficiency. Gastrointestinal disturbances caused by local irritation are the most common adverse effects caused by iron supplements. 

Lanzilotta, W.N and Seefeldt, L.C. (1997) Changes in the midpoint potential of the nitrogenase metal centers as a result of iron protein-molybdenum-iron protein complex formation, Biochemistry 36, 12976-12983. 

Haemosiderin is also an iron-protein complex, assumed to be formed from ferritin. In the case of iron overload in the body, more haemosiderin than ferritin is formed, which is then stored in the intracellular space. Haemosiderin can be demonstrated biochemically using the Berlin blue reaction, (see chapters 5.5.2 and 31.17)... 

A protein of the white of an egg which may combine with iron salts to form a red iron-protein complex. This accounts for the pinkish color resulting when eggs are stored in rusty containers. 

The iron-protein complex in which iron is stored, particularly in the cells of the liver, spleen, and bone marrow. 

Three protein complexes have been isolated, including the flavoprotein (FP), iron-sulfur protein (IP), and hydrophobic protein (HP). FP contains three peptides (of mass 51, 24, and 10 kD) and bound FMN and has 2 Fe-S centers (a 2Fe-2S center and a 4Fe-4S center). IP contains six peptides and at least 3 Fe-S centers. HP contains at least seven peptides and one Fe-S center. 

Heme (C34H3204N4Fe) represents an iron-porphyrin complex that has a protoporphyrin nucleus. Many important proteins contain heme as a prosthetic group. Hemoglobin is the quantitatively most important hemoprotein. Others are cytochromes (present in the mitochondria and the endoplasmic reticulum), catalase and peroxidase (that react with hydrogen peroxide), soluble guanylyl cyclase (that converts guanosine triphosphate, GTP, to the signaling molecule 3, 5 -cyclic GMP) and NO synthases. 

Molybdenum hexafluoride. 3,1412 Molybdenum-iron-sulfur complexes, 4,241 Molybdenum oxide amino acid formation prebiotic systems, 6, 872 Molybdenum storage protein microorganisms, 6, 681 Molybdenum telluride, 3, 1431 Molybdenum tetraalkoxides physical properties, 2, 347 Molybdenum tribromide, 3,1330 Molybdenum trichloride, 3,1330 Molybdenum trifluoride, 3, 1330 Molybdenum trihalides, 3, 1330 bond lengths, 3, 1330 magnetic moments, 3,1330 preparation, 3,1330 properties, 3, 1330 structure, 3,1330 Molybdenum triiodide, 3,1330 Molybdenum trioxide complexes, 3, 1379 Molybdenum triselenide, 3, 143)... 

Figure 12-6. Iron-sulfur-protein complex (Fe4S4). d acid-labile sulfur Pr,apoprotein Cys, cysteine residue. Some iron-sulfur proteins contain two iron atoms and two sulfur atoms (FejSj).

The general influence of covalency can be qualitatively explained in a very basic MO scheme. For example, we may consider the p-oxo Fe(III) dimers that are encountered in inorganic complexes and nonheme iron proteins, such as ribonucleotide reductase. In spite of a half-filled crystal-field model), the ferric high-spin ions show quadrupole splittings as large as 2.45 mm s < 0, 5 = 0.53 mm s 4.2-77 K) [61, 62]. This is explained... 

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