Aerobic metabolism properties

Mitochondria are intracellular centers for aerobic metabolism. They are cell organelles that are identified by well-defined structural and biochemical properties. In morphological terms, mitochondria are relatively large particles that are characterized by the presence of two membranes, a smooth outer membrane that is permeable to most important metabolites and an inner membrane that has unique transport properties. The inner membrane is highly folded, which serves to increase its surface area. Figure E10.1, which shows the structure of a typical mitochondrion, divides the organelle into four major components inner membrane, outer membrane, intermembrane space, and the matrix. These regions are associated with different and... 

Misonidazole [27 l-methoxy-3-(2-nitroimidazol-l-yl)-2-propanol] and the model compound l-methyl-2-nitroimidazole have been used as radiosensitizers in the treatment of certain types of human tumors. One important property of these compounds is that they are more toxic to hypoxic cells than to aerobic cells, indicating that reductive metabolism of the drug is involved in the toxicity. Results of a number of studies suggest that intracellular thiols play a significant role in the hypoxic cell toxicity, and it was found that reduction products formed stable thio ethers with GSH (for literature see References 181-183). The reaction mechanism of thio ether formation has not been fully established. It has been suggested that the 4-electron reduction product was involved in thio ether formation181,184,185, and that the hydroxylamine rather than the nitroso derivative was the reactant. On the other hand, an intermediate nitroso derivative is expected to give a sulfenamide cation (see Scheme 1) which easily allows thio ether formation. 

Free radical formation is associated with the normal natural metabolism of aerobic cells. The oxygen consumption inherent to cell growth leads to the generation of a series of free radicals. The interaction of these species with molecules of a lipid nature produces new species such as hydroperoxides and different kinds of peroxides [135, 136], This group of radicals (superoxide, hydroxyl, and lipoid peroxides) may interact with biological systems in a cytotoxic manner. In this respect, it has been shown to posses an important antioxidant activity towards these radicals, which is mainly based on the properties of the hydroxyphenolic groups and the structural relations between the different parts of the chemical structure. Together with an ability to capture electrons, these... 

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