Iron-containing proteins myoglobins

C. F. Harrington, S. Elahi, S. A. Merson, P. Ponnampalavanar, Quantitative analysis of iron-containing protein myoglobin in different foodstuffs by liquid chromatography coupled to high-resolution inductively coupled plasma mass spectrometry, J. AOAC Int., 87 (2004), 253 D258. 

Iron-containing compounds in biological and clinical samples have been studied by separating them on chromatographic columns that were coupled to inductively coupled plasma mass spectrometers. Four iron-containing proteins, namely ferritin, haemoglobin, myoglobin and cytochrome-c were separated on a gel permeation column (Takatera and Watanabe, 1991). The absolute detection limits were 0.01-1 mg for the four proteins when 10 ml injections of samples were analysed. In other research, excess iron accumulations in human and animal... 

Spectroscopic data obtained from spectroelectrochemical experiments require careful and case-specific analysis. The Fe /Fe redox couple has a unique role in diflferent iron-containing proteins. It is hypothesised that the mammalian iron-transport protein transferrin uses the Fe /Fe redox couple as a switch that controls the time and site-specific release of iron, while other iron-containing proteins, such as myoglobin, are able to hold on to iron in both oxidation states. Therefore, it is very important to evaluate the protein and its interaction with both the oxidised and reduced states of iron and accordingly develop a data-analysis model. The spectroelectrochemical response of an iron binding protein can be ideal Nernstian, non-Nernstian resulting from coupled... 

In liver, muscle and other tissues iron is taken up by the cells when transferrin saturation levels are high and deposited first in ferritin and subsequently transferred to haemosiderin. This pool of ferritin iron is most likely used within these cells to meet requirements for synthesis of haem enzymes, myoglobin and other non-haem iron proteins. The ferritin can also store iron released from the breakdown of such iron containing proteins in the course of their turnover. Mobilisation of iron from these tissues once again probably involves reduction of iron to Fe2+ and its transfer across the cell membrane to transferrin. In such tissues the level of transferrin saturation seems likely to play a major role in determining the balance between deposition of iron in ferritin and its mobilization from the storage form. 

Enzymic changes in tissues other than the erythron and the epithelia have also been reported in iron deficiency the levels of iron-containing proteins—such as myoglobin, cytochrome, catalase, and others—are reduced. But the decrase in cytochrome activity must affect only the enzyme reserves because it is not accompanied by a corresponding decrease in oxygen uptake. 

The 4 g of iron in the human body is normally com-partmented into its functional locations in the haem- and non-haem-containing, and iron-binding proteins and enzymes (Fig. 3.5). The majority (65%) of the iron is in the divalent state in haemoglobin and myoglobin, which are involved in the transport and storage of oxygen in erythrocytes and myocytes, respectively. The remainder is distributed between storage sites, predominantly in the... 

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. 

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