Peroxidase lipid oxidation

Muscle tissues contain a multi-component antioxidant system consisting of lipid-soluble compounds (a-tocopherol, ubiquinone), water-soluble compounds (ascorbate, histidine-dipeptides) and enzymes (superoxide dismutase, catalase, glutathione peroxidase). Lipid oxidation in meats can be effectively controlled by the use of various phenolic compounds derived from spice extracts, by vitamin E supplementation of animal diets, and by processing of cured meat with sodium nitrite. Various natural antioxidant formulations containing mixtures of tocopherols, ascorbyl palmitate and citric acid show synergistic effects in stabilizing cooked and frozen meat. Synthetic antioxidants, BHA, TBHQ, propyl gallate (see Chapter 9) and combinations with citric acid, ascorbic acid or phosphates are also effective formulations used to retard lipid oxidation in... 

A number of NO-derived reactive species can initiate lipid peroxidation, including nitrogen dioxide and, most notably, ONOO , which displays unique properties as a mediator of lipid oxidation. On a molecular basis, ONOO is a more potent lipid oxidant than hydrogen peroxide and, unlike H2O2, it does not require metal catalysis. The one-electron oxidants such as metals, as well as heme proteins and peroxynitrite, are assumed to play an important role in many diseases associated with oxidative stress. Heme proteins such as horseradish peroxidase (HRP) can produce alkylperoxyl radicals through two sequential... 

Adams, J.B., Harvey, A., and Dempsey, C.E. 1996. Regenerated and denatured peroxidase as potential lipid oxidation catalysts. Food Chem. 57 505-514. 

Adam W, Kurz A, Saha-Moller CR (2000a) Peroxidase-catalyzed oxidative damage of DNA and 2 -de-oxyguanosine by model compounds of lipid hydroperoxides involvement of peroxyl radicals. Chem Res Toxicol 13 1199-1207... 

Kl. Kalyanaraman, B., Darley-Usmar, V., Struck, A., Hogg, N., and Parthasarathy, S., Role of apolipoprotein B-derived radical and alpha-tocopheroxyl radical in peroxidase-dependent oxidation of low density lipoprotein. J. lipid Res. 36, 1037-1045 (1995). 

Peroxide value is the measure of reactive oxygen content of a fat in terms of milliequivalents per 1000-g fat, following AOCS method Cd 8-53 or AOAC Method 965.33 (109). Elevated peroxide values indicate that lipid oxidation has taken place (110). Free fatty acids can serve as substrates for lipoxygenase and peroxidase (111), both of which are inactivated during heating (112). Once the cell... 

Catalase (D. Keilin et al., 1945) is localized in the peroxisomes alcohol is oxidized via intermediate steps to xanthine by means of xanthine oxidase. This releases H2O2, which is deactivated with the help of glutathione and then split into oxygen and water. By way of this peroxidase reaction, alcohol can also be degraded to acetaldehyde. (12) However, in the case of chronic alcohol consumption, glutathione is bound to acetaldehyde with the result that the released H2O2 can intensify lipid oxidation, (s. fig. 3.16)... 

Lipid Peroxidation Peroxidase catalyzed oxidation of Hpids using hydrogen peroxide as an electron acceptor, [nih]... 

Several oxysterol classes present in oxLDL appear to be cytotoxic toward fibroblasts, ECs, and vascular smooth muscle cells, especially 7-hydroperoxycholes-terol (7-OOH-chol), 7P- and 7a-hydroxycholesterol (7-OH-chol), 7-ketocholesterol (7-keto-chol), and cholesterol epoxides (epoxy-chol). 7p-OOH-chol, a precursor of hydroxyl- and keto-oxysterols, was reported to be the most toxic. During LDL oxidation 7P-OOH-chol was produced in three to five times higher quantities than 7a-OOH-chol, other oxysterols and even hydroxy-nonenal, which is one of the most abundant lipid oxidation products. Cytotoxicity of oxysterols was connected to increased cellular oxidative stress. Some studies suggest that oxysterols are even involved in oxidative stress induction. Animal models indicate that dietary oxysterols can significantly decrease glutathione levels and increase expression of glutathione peroxidase and superoxide dismutase. In apolipoprotein-deficient mice, the NADPH-oxidase activity was induced by 7-keto-chol, 7p-OH-chol, and Sp,6P-epoxy-chol. The increased activity of NADPH oxidase yields more superoxide anions that amplify oxidative stress. 

Table 11.1. Effect of temperature on activity of horseradish peroxidase and on non-enzymatic lipid oxidation. ...

The unsaturated lipids in living tissue are relatively stable. Plants and animals have the necessary complement of antioxidants and of enzymes, for instance, glutathione peroxidase and superoxide dismutase, to effectively prevent lipid oxidation. 

Bogan L, RT Lamar, KE Hammel (1996) Fluorene oxidation in vivo by Phanerochaete chrysosporium and in vitro during manganese peroxidase-dependent lipid peroxidation. Appl Environ Microbiol 62 1788-1792. 

Moen MA, KE Hammel (1994) Lipid peroxidation by the manganese peroxidase of Phanerochaete chrysosporium is the basis for phenanthrene oxidation by the intact fungus. Appl Environ Microbiol 60 1956-1961. 

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