Chelatable iron

Iron Oxides. Chelated iron oxide, using nittilotriacetic acid [139-13-9] and EDTA, has been studied as an alternative oxygen source (35). Iron oxide which is often difficult for the microbes to access, is made more available by chelating agents. 

Fe304 + Fe + 8H+ + 4chelant > 4Fe(ll)chelant + 4H20 magnetite steel hydrogen chelated iron water... 

Where an alkaline EDTA cleaning program is employed, hydrazine sometimes is added to help keep the chelated iron in the ferrous state and prevent corrosion of exposed steel. Under very exacting circumstances, such as removing iron oxides from nuclear powered SGs, triammonium EDTA together with 0.5 M hydrazine may be employed, at a pH of 7 and a temperature of 200 °F (93 °C). 

Kennedy, T.P., Rao, N.V., Noah, W., Michael, J.R., Jaffri, M.H., Gurtner, G.H. and Hoidal, J.K (1990). Ibuprofen prevents oxidant lung injury and in vitro lipid peroxidation by chelating iron. J. Clin. Invest. 86, 1565-1573. 

Lipid peroxidation (see Fig. 17.2) is a chain reaction that can be attacked in many ways. The chain reaction can be inhibited by use of radical scavengers (chain termination). Initiation of the chain reaction can be blocked by either inhibiting synthesis. of reactive oxygen species (ROS) or by use of antioxidant enzymes like superoxide dismutase (SOD), complexes of SOD and catalase. Finally, agents that chelate iron can remove free iron and thus reduce Flaber-Weiss-mediated iron/oxygen injury. 

Moreover, redox cycling of free or weekly chelated iron may decompose a lipid hydroperoxide and thus initiate a chain of lipid peroxidation (Halliwell and Gutteridge, 2000). 

Hahn, P, Milam, AH, and Dunaief, JL, 2003. Maculas affected by age-related macular degeneration contain increased chelatable iron in the retinal pigment epithelium and Bruch s membrane. Arch Ophthalmol 121, 1099-1105. 

Compounds that strongly chelate iron have been known for many years to stabilize HIF-la as well as upregulate proteins involved in red blood cell production erythropoietin (EPO), angiogenesis, vascular endothelial growth factor (VEGF), and iron transport. Some, but not all, of the pharmacological actions of iron chelators are produced by inhibition of PHD enzymes resulting in elevation of cellular HIF content. The action of selected iron chelators as they relate to PHD inhibition are briefly summarized here. 

Frequently, metal ions are associated with the prosthetic group or cofactor. Heme rings usually contain a chelated iron atom. Occasionally, however, these metals are merely bound within folded polypeptide regions with no additional organic constituents required. Many metal ions are known to participate in enzymatic activity. One or more of the ions of Na, K, Ca, Zn, Cu, Mg, Mn, as well as Co and Mo are often required by enzymes to maintain activity. 

Hiperion A process for removing hydrogen sulfide and organic sulfur compounds from hydrocarbons. Similar to the Takahax process but using a solution of chelated iron and naphthaquinone. The elemental sulfur produced is removed by filtration. Licensed by Ultrasystems, CA. 

In addition to the hydroxamates there are other low molecular weight species produced by protista which chelate iron. In general, these chelators contain the 2,3-dihydroxybenzoyl moiety, such as 2,3-dihydroxy-N-benzoyl-Z,-serine, 2,3-dihydroxy-N-benzoylthreonine, 2,3-dihydroxy-N-benzoyl-glycine, and enterochelin (84). 

The ability of hydroxamic acids to chelate iron provided the rationale for... 

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