Oxygen-induced changes in pulmonary superoxide dismutase assayed by antibody titrations
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Previous studies have demonstrated a 50% increase in pulmonary superoxide dismutase (SOD) activity in oxygen-adapted rats and have suggested that SOD plays a significant role in the development of "tolerance". To further study these events, the cuprozinc SOD was purified from rat liver and found to be similar to previously purified cuprozinc superoxide dismutases. A rabbit antisera to rat cuprozinc SOD was produced and used to perform antibody titrations of SOD in the lungs of rats exposed to 85% O2 for 5 days. The absolute amount of cuprozinc SOD increased 41% by antibody titration which accounted for most, if not all, of the 48% increase demonstrated in total SOD activity. Spectrophotometric assays at pH 7.8 and 10.0 of pure rat cuprozinc SOD and crude lung homogenates suggest that there is also a manganese SOD present, but the role of that SOD in the development of oxygen tolerance has not been established.Keywords:
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Superoxide dismutase is an important antioxidant enzyme in animals and plays an important role to remove excess free radicals which achieved mainly through the copper-zinc superoxide dismutase and manganese superoxide dismutase. Copper may directly or indirectly affect the copper-zinc superoxide dismutase activity, while the change of reactive oxygen species induced by copper deficiency may regulate manganese superoxide dismutase expression through the transcription factor NF-κB and AP-1.
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Abstract: In some families with amyotrophic lateral sclerosis (ALS), the disease is linked to mutations in the gene encoding CuZn‐superoxide dismutase. The mutant CuZn‐superoxide dismutases appear to cause motor neuron degeneration by a toxic property, suggested to be linked to an altered reactivity of the active‐site Cu ions. Asp 90 Ala mutant CuZn‐superoxide dismutase was isolated from six patients with ALS, allowing properties of the mutant enzyme synthesized and conditioned in patients with ALS to be examined. The molecular mass of the Asp 90 Ala mutant CuZn‐superoxide dismutase was 45 Da lower than that of the wild‐type enzyme, as expected from the amino acid exchange. The mobility after sodium dodecyl sulfate‐polyacrylamide gel electrophoresis was markedly increased, however, suggesting altered properties of the polypeptide. The mutant CuZn‐superoxide dismutase showed a minimal reduction in stability but did not differ significantly from the wild‐type enzyme in enzymic activity, in content and affinity for active‐site Cu ions and in the propensity to catalyze formation of hydroxyl radicals. Our findings suggest that the deleterious effect of mutant CuZn‐superoxide dismutases on motor neurons in ALS is not related to altered reactivity of active‐site Cu ions, resulting in increased oxidant stress. Attention should therefore also be directed at other mechanisms and properties of the mutant polypeptides and their degradation products.
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Superoxide Dismutase(SOD)(EC 1.15.1.1)is a metalloenzyme that is found in almost all organisms and catalyzes the dismutation of superoxide anion radical to hydrogen peroxide and molecular oxygen.Three unique and highly compartmentalized mammalian SOD have been biochemically and molecularly characterized to date:Cu,Zn superoxide dismutase(CuZnSOD,SOD1), MnSOD(Manganese Superoxide Dismutase,SOD2)and EC-SOD(Extracellular Superoxide Dismutase,SOD3).Cu,Zn superoxide dismutase(CuZnSOD,SOD1)is a copper and zinc-containing homodimer that is found almost exclusively in intracellular cytoplasmic spaces.CuZnSOD is widely distributed and comprises about 90% of the total SOD.Cytoplasmic and periplasmic SOD exists as dimers, whereas chloroplastic and extracellular enzymes exist as tetramers.Structure supports independent functional evolution in prokaryotes and eukaryotes.CuZnSOD are thought to protect the brain,lungs,and other tissues from oxidative stress.This paper reviewed the gene, molecular and chemical structure and biological function of CuZnSOD.
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Preparations of liver large granule fraction from control and copper-injected rats were treated with digitonin (0.01-0.16 mg/mg protein) and supernatants rich in lysosomal matrix and in mitochondrial intermembrane space were obtained. After copper injection the superoxide dismutase activity in all supernatants was significantly increased. The granular CuZn-superoxide dismutase in the two animal groups was localized in lysosomes only. The cytosolic and lysosomal CuZn-superoxide dismutase in control preparations showed an equal electrophoretic pattern (two peaks with Rf = 0.42 and 0.47). After copper injection three new electrophoretic peaks of the lysosomal CuZn-superoxide dismutase activity (with Rf = 0.37, 0.52 and 0.62 respectively) appeared. The increased heterogeneity of the granular CuZn-superoxide dismutase activity after copper injection is explained by the oxidative degradation of the CuZn-superoxide dismutase in lysosomes.
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This study was conducted to observe intracellular antioxidant cooper,zinc-superoxide dismutase (Cu,Zn-SOD) in liver tissue of rats under hypercholesterolemic condition by using immunohistochemical technique. A total of twenty male Wistar rats were used for this study. Those rats were divided into two groups; (i) control group and (ii) hypercholesterolemic group, which were fed died containing 1% cholesterol for eight weeks. Rat livers were taken at the end of treatment, and processed by using paraffin embedding standard method. The tissues were stained immunohistochemically to Cu,Zn-SOD. Observation of Cu,Zn-SOD content in the tissue was performed qualitatively in the cytoplasm and quantitatively in the nucleus of hepatocytes based on colour intensity of enzyme reaction product. The profile of antioxidant-Cu,Zn-SOD decreased (P Key words: Superoxide dismutase (SOD), hypercholesterolemia, liver, rat
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Oxidant stress is a key mechanism for smoking-induced chronic obstructive pulmonary disease (COPD). Smoking has been shown to upregulate several antioxidant enzymes, with potential effects on the prevention of the disease and/or its progression. Superoxide dismutases (SOD)s are the only enzymes capable of consuming superoxide radicals. The purpose of the present study was to investigate SODs in the lungs of nonsmokers, smokers and COPD patients. Manganese superoxide dismutase (MnSOD), copper zinc SOD (CuZnSOD), and extracellular SOD (ECSOD), were investigated by immunohistochemistry in the airways of 13 nonsmokers, 20 smokers and 22 COPD patients with mild-to-moderate disease. Lung tissue homogenates of three nonsmokers and four smokers were used for Western blot and enzyme activity analysis. The expression of MnSOD was higher in the central bronchial epithelium of smokers with COPD and in the alveolar epithelium of smokers without or with COPD than innonsmokers. Lung MnSOD immunoreactivity, evaluated by Western blotting and specific activity, were 33% and 51% higher, respectively, in smokers than in nonsmokers. No major changes could be observed in lung CuZnSOD or ECSOD immunoreactivities. Manganese superoxide dismutase is elevated in the alveolar epithelium of cigarette smokers, probably due to the increased oxidant burden in smokers' lungs.
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Abstract Rete mirabile and gas gland epithelium from the swim bladders of six species of marine fishes were assayed for catalase, glutathione peroxidase, and superoxide dismutase activity. Correlation of the results of these assays with measurements of the concentration of oxygen in the lumen of the normal steady state swim bladders revealed that swim bladders in species containing higher levels of oxygen also exhibited higher levels of superoxide dismutase activity in the rete mirabile/gas gland epithelium region. There appeared to be no correlation between oxygen concentration and the level of catalase or glutathione peroxidase activity. Induction of the inflatory reflex in Opsanus tau by a single deflation of the swim bladder resulted in an increase in the percent of oxygen in the swim bladder lumen 18 to 24 hours later, but this was not accompanied by any significant increases in antioxidant enzyme activity. Swim bladders that were deflated three times at 24‐hour intervals showed further increases in oxygen concentration at the end of the 72‐hour period but no alteration in superoxide dismutase activity.
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Previous studies have demonstrated a 50% increase in pulmonary superoxide dismutase (SOD) activity in oxygen-adapted rats and have suggested that SOD plays a significant role in the development of "tolerance". To further study these events, the cuprozinc SOD was purified from rat liver and found to be similar to previously purified cuprozinc superoxide dismutases. A rabbit antisera to rat cuprozinc SOD was produced and used to perform antibody titrations of SOD in the lungs of rats exposed to 85% O2 for 5 days. The absolute amount of cuprozinc SOD increased 41% by antibody titration which accounted for most, if not all, of the 48% increase demonstrated in total SOD activity. Spectrophotometric assays at pH 7.8 and 10.0 of pure rat cuprozinc SOD and crude lung homogenates suggest that there is also a manganese SOD present, but the role of that SOD in the development of oxygen tolerance has not been established.
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