Peroxidases iron-heme-dependent

The peroxidase activity of PGHS is comparable to that of better known peroxidases such as horseradish peroxidase (HRP). The catalytic cycle of HRP is shown in Figure 5 [9], Its first step is the formation of an intermediate very often found in hemoproteins by transfer of an oxygen atom from various oxygen atom donors to the Fe(III) heme (Eq. 6). It is a high-valent iron-oxo species, at least formally a Fe(V)=0 complex. In fact, the detailed electronic structure of this intermediate depends on the environment of the heme provided by the protein. In HRP, this intermediate (called compound I) is a (porphyrin radical-cation)-Fe(IV)=0 complex, as shown by many spectroscopic techniques [9],... 

The modulation of redox potential in heme peroxidases depends on the factors described in Table 4.2. Iron pentacoordination is conserved among peroxidases, being the most common ligand the NE from a histidine residue. There are exceptions,... 

Horseradish peroxidase (HRP) is an important peroxidase that contains heme, which is the protein active site with the resting state of the heme iron, Fe(III), as prosthetic group. It can catalyze the dependent one-electron oxidation of a great variety of substrates, and has been commonly employed to construct biosensors (Hai-Li Zhang et al. 2008). Peroxidase is the most frequently used enzyme for the construction of immunosensors. Successful immobilization of horseradish peroxidase on modified magnetic particles and their employment in the amperometric biosensors are mentioned in (Hai-Li Zhang et al. 2008 Yu et al. 2006). 

Iron deficiency is the most common nutritional cause of anemia in humans. It can result from inadequate iron intake, malabsorption, blood loss, or an increased requirement, as with pregnancy. When severe, it results in a characteristic microcytic, hypochromic anemia. Iron is an essential component of myoglobin heme enzymes such as the cytochromes, catalase, and peroxidase and the metalloflavoprotein enzymes, including xanthine oxidase and the mitochondrial enzyme a-glycerophosphate oxidase. Iron deficiency can affect metabohsm in muscle independent of the effect of anemia on delivery, possibly due to a reduction in the activity of iron-dependent mitochondrial enzymes. Iron deficiency also has been associated with behavioral and learning problems in children, abnormahties in catecholamine metabolism, and impaired heat production. 

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