Hemoglobin myoglobin

Fe2+,Fe3+ 5000 mg 15mg Component of hemoglobin, myoglobin Liver, meat clams, spinach... 

Table 3.4 lists values for A Eq and for some important oxidation and spin states found in bioinorganic molecules. Data are taken from reference 24 and from Table 1 of reference 25 for hemoglobin, myoglobin, and the picket-fence porphyrin model compound, FeTpivPP(l-Melm).25 The myoglobin and hemoglobin model compounds are discussed in Section 4.8.2. Reference 26 provides the Table 3.4 data on iron sulfur clusters found in many bioinorganic species.26 The unusual iron-sulfur and iron-molybdenum-sulfur clusters found in the enzyme nitrogenase are discussed more fully below and in Chapter 6. 

Hemoglobin, myoglobin, cytochrome C, and cytochrome oxidase are all electrochemically reduced in the presence of quinoxaline. Quinoxaline is preferentially reduced to the anion radical that can release its electron. Metalloproteins can serve as the electron acceptors in which the metal ion is reduced [424]. 

Fig. 1. Overview of intravascular heme catabolism. Hemoglobin, myoglobin, and other heme proteins are released into the circulation upon cellular destruction, and the heme moiety is oxidized by O2 to the ferric form (e.g., methemoglobin and metmyoglobin). Haptoglobin can bind a substantial amount of hemoglobin, but is readily depleted. Ferric heme dissociates from globin and can be bound by albumin or more avidly by hemopexin. Hemopexin removes heme from the circulation by a receptor-mediated transport mechanism, and once inside the ceU heme is transported to heme oxygenase for catabolism.

Transport — creation of hemoglobin, myoglobin, albumin and other transport proteins ... 

Heme coenzymes (8) with redox functions exist in the respiratory chain (see p. 140), in photosynthesis (see p. 128), and in monooxygenases and peroxidases (see p. 24). Heme-containing proteins with redox functions are also referred to as cytochromes. In cytochromes, in contrast to hemoglobin and myoglobin, the iron changes its valence (usually between +2 and +3). There are several classes of heme (a, b, and c), which have different types of substituent - Ri to - R 3. Hemoglobin, myoglobin, and the heme enzymes contain heme b. Two types of heme a are found in cytochrome c oxidase (see p. 132), while heme c mainly occurs in cytochrome c, where it is covalently bound with cysteine residues of the protein part via thioester bonds. 

The last column in the table lists some of the functions of minerals. It should be noted that almost all of the macroelements in the body function either as nutrients or electrolytes. Iodine (as a result of its incorporation into iodothyronines) and calcium act as signaling substances. Most trace elements are cofactors for proteins, especially for enzymes. Particularly important in quantitative terms are the iron proteins hemoglobin, myoglobin, and the cytochromes (see p. 286), as well as more than 300 different zinc proteins. 

Pharmacology Iron, an essential mineral, is a component of hemoglobin, myoglobin, and a number of enzymes. Approximately two-thirds of total body iron is in the circulating red blood cell mass in hemoglobin, the major factor in oxygen transport. 

Iron occurs in every mammalian cell and is vital for life processes. It is bound to various proteins and found in blood and tissues. The iron-porphyrin or heme proteins include hemoglobin, myoglobin and various heme enzymes, such as cytochromes and peroxidases. Also, it occurs in non heme compounds, such as ferritin, siderophilin, and hemosiderin. Hemoglobin, found in the red blood cells, is responsible for transport of oxygen to the tissue cells and constitutes about two-thirds (mass) of all iron present in the human body. An adult human may contain about 4 to 6 grams of iron. 

T. Kutsuzawa, S. Shioya, D. Kurita and M. Haida, Deoxygenated hemoglobin/myoglobin kinetics of forearm muscle from rest to exercise in patients with chronic obstructive pulmonary disease. Tohoku ]. Exp. Med., 2009, 217,9-15. 

Complex heterocyclic compounds Porphyrins and bile pigments Hemoglobins, myoglobins, cytochromes Alkaloids... 

Rota et al. [81,82] concluded that DCF fluorescence could not be a reliable assay of superoxide detection in cells because superoxide is formed during the DCFH oxidation by peroxidases. It has also been shown that DCFH is oxidized by heme, hemoglobin, myoglobin, and cytochrome c [83]. However, recent work by Caldefie-Chezet et al. [84] showed that the measurements of superoxide production by PMNs with the use of 2 -7 -dichlorofluorescin diacetate flow cytometry correlated with the data obtained by lucigenin- and luminol-amplified CL assays. 

Structure and use of porphyrins Porphyrins are cyclic compounds that readily bind metal ions—usually Fe2+ or Fe3+ The most prevalent metalloporphyrin in humans is heme, which is found in hemoglobin, myoglobin, cytochromes, and the enzymes catalase and tryptophan pyrrolase. 

Fig. 19.2 The heme group Type A hemes are found in cytochrome n Type B hemes are found in hemoglobin, myoglobin, peroxidase, and cytochrome b Type C hemes are found in cytochrome c chloroheme is found in chlorocruorin...

The facility of metal complex formation is underscored by the fact that most porphyrin systems with any type of physiological function occur as metal complexes (e.g. Fe in hemoglobins, myoglobins, cytochromes, catalases and peroxidases Mg in chlorophylls and bacteriochlorophylls Co in vitamin B12). 

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