Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.15.1.1 (superoxide dismutase)
58,858 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Picroliv, the active principle of Picrorhiza kurrooa, and its main components which are a mixture of the iridoid glycosides, picroside-I and kutkoside, were studied in vitro as potential scavengers of oxygen free radicals. The superoxide (O2-) anions generated in a xanthine-xanthine oxidase system, as measured in terms of uric acid formed and the reduction of nitroblue tetrazolium were shown to be suppressed by picroliv, picroside-I and kutkoside. Picroliv as well as both glycosides inhibited the non-enzymic generation of O2- anions in a phenazine methosulphate NADH system. Malonaldehyde (MDA) generation in rat liver microsomes as stimulated by both the ascorbate-Fe2+ and NADPH-ADP-Fe2+ systems was shown to be inhibited by the Picroliv glycosides. Known antioxidants tocopherol (vitamin E) and butylated hydroxyanisole (BHA) were also compared with regard to their antioxidant actions in the above system. It was found that BHA afforded protection against ascorbate-Fe(2+)-induced MDA formation in microsomes but did not interfere with enzymic or non-enzymic O2- anion generation; and tocopherol inhibited lipid peroxidation in microsomes by both prooxidant systems and the generation of O2- anions in the non-enzymic system but did not interfere with xanthine oxidase activity. The present study shows that picroliv, picroside-I and kutkoside possess the properties of antioxidants which appear to be mediated through activity like that of superoxide dismutase, metal ion chelators and xanthine oxidase inhibitors.
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PMID:Picroliv, picroside-I and kutkoside from Picrorhiza kurrooa are scavengers of superoxide anions. 132 26

By microsomes obtained from bovine ciliary body, 1,1-diphenylhydrazine was oxidized to N-nitrosodiphenylamine in the presence of NADPH. This reaction was stimulated by riboflavin which was recognized to be an electron carrier. The oxidizing activity by microsomes was markedly inhibited by superoxide dismutase, but not by SKF 525-A or carbon monoxide. Similarly, the oxidation of 1,1-diphenylhydrazine to its corresponding nitrosamine occurred in varying degrees when the hydrazine derivative was exposed to visible light in the presence of photosensitizers such as riboflavin, flavin adenine dinucleotide, flavin mononucleotide, lumiflavin, lumichrome, NAD+, NADH, NADP+, or NADPH. The photochemical oxidation was inhibited by active oxygen-scavengers such as superoxide dismutase, L-ascorbic acid or alpha-tocopherol. The superoxide radical involved in the photochemical reaction was determined by measuring the oxidation of epinephrine to adrenochrome. The oxidation of epinephrine was well correlated to that of 1,1-diphenylhydrazine. Thus, the present study provided evidence that the superoxide radical is responsible for the oxidation of a hydrazine derivative to a corresponding nitrosamine by ocular tissue microsomes and by photosensitizers.
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PMID:Oxidation of 1,1-diphenylhydrazine to N-nitrosodiphenylamine by superoxide radical in the eye. 132 25

Peroxisomes are subcellular respiratory organelles which contain catalase and H2O2-producing flavin oxidases as basic enzymatic constituents. These organelles have an essentially oxidative type of metabolism and have the potential to carry out different important metabolic pathways. In recent years the presence of different types of superoxide dismutase (SOD) have been demonstrated in peroxisomes from several plant species, and more recently the occurrence of SOD has been extended to peroxisomes from human and transformed yeast cells. A copper,zinc-containing SOD from plant peroxisomes has been purified and partially characterized. The production of hydroxyl and superoxide radicals has been studied in peroxisomes. There are two sites of O2- production in peroxisomes: (1) in the matrix, the generating system being xanthine oxidase; and (2) in peroxisomal membranes, dependent on reduced nicotinamide adenine dinucleotide (NADH), and the electron transport components of the peroxisomal membrane are possibly responsible. The generation of oxygen radicals in peroxisomes could have important effects on cellular metabolism. Diverse cellular implications of oxyradical metabolism in peroxisomes are discussed in relation to phenomena such as cell injury, peroxisomal genetic diseases, peroxisome proliferation and oxidative stress, metal and salt stress, catabolism of nucleic acids, senescence, and plant pathogenic processes.
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PMID:Metabolism of oxygen radicals in peroxisomes and cellular implications. 133 30

ESR spin trapping measurements demonstrate generation of hydroxyl (.OH) radical from reduction of vanadate by rat liver microsomes/NADH without exogenous H2O2. Catalase decreases the .OH signal while increasing a vanadium (4+) signal. Addition of superoxide dismutase (SOD) or measurements under an argon atmosphere show decreased .OH radical production. The results suggest that during the one-electron vanadate reduction process by microsomes/NADH, molecular oxygen is reduced to H2O2, which then reacts with vanadium (4+) to generate .OH radical via a Fenton-like mechanism.
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PMID:Hydroxyl radical generation in the NADH/microsomal reduction of vanadate. 133 35

Pure rat liver heavy mitochondrial fractions, in which the absence of significant microsomal contamination was confirmed by electron microscopy and by the lack of glucose-6-phosphatase activity, were used to demonstrate the effect of paraquat on mitochondrial ultrastructure in the presence of external NADH. Starved mitochondria (orthodox conformation) did not show O2 uptake or structural injury from either paraquat alone or NADH alone. Marked O2 uptake and structural breakage occurred only when paraquat and NADH were added in combination. These alterations were resistant to rotenone and malate plus glutamate or NADPH could not substitute for NADH. Paraquat was reduced anaerobically by the mitochondria in the presence of NADH, but not of NADPH. The addition of superoxide dismutase, ferricytochrome c or p-benzoquinone protected against the breakage of mitochondria caused by paraquat plus NADH. These results demonstrate that mitochondria may produce paraquat radicals in the presence of extramitochondrial NADH and thus generate superoxide anion radicals, resulting in structural injury to the mitochondria, by mechanisms that may involve the mitochondrial outer membrane rather than the electron transfer chain. These mitochondrial mechanisms in paraquat toxicity seemed to be more probable in vivo than are microsomal mechanisms; the latter are postulated to function in detoxication because phenobarbital diminished paraquat toxicity and SKF 525-A or cobaltous ions enhanced the toxicity.
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PMID:Paraquat damage of rat liver mitochondria by superoxide production depends on extramitochondrial NADH. 134 81

Polyoxyethylene-modified superoxide dismutase (SOD-POE) is a newly developed long-acting superoxide dismutase. Adriamycin (ADR) and mitomycin C (MMC) generate superoxide, which contributes to their cytocidal effects or side effects. We examined whether SOD-POE could prevent the side effects induced by superoxide generated by antitumor agents, and the following results were obtained. SOD-POE did not influence the antitumor effects of ADR and MMC either in vitro or in vivo, but prevented the toxic death of BALB/c, nu/nu male mice caused by overdoses of ADR or MMC. As for its effective sites, SOD-POE prevented a decrease in the specific activity of rotenone-sensitive NADH-ubiquinone oxido-reductase (complex I) in heart muscle mitochondrial respiratory chain function in BALB/c male mice administered 10 mg/kg ADR, and prevented damage to the sarcoplasmic reticulum and mitochondria of mouse heart muscle by ADR as observed by electron microscopy. Furthermore, SOD-POE prevented bone marrow suppression induced by MMC in Donryu rats. The above results suggest that combination chemotherapy with SOD-POE would make it possible to increase the maximum permissible doses of antitumor agents, improving the efficacy of these agents.
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PMID:Polyoxyethylene-modified superoxide dismutase reduces side effects of adriamycin and mitomycin C. 139 27

A new spectrophotometric method for determining low hydrogen peroxide concentrations by using horseradish peroxidase in the presence of NADH at pH 7.5 has been described. Both total NADH consumption and initial reaction rate may be used for the determination. Using the NADH consumption, a linear response with respect to hydrogen peroxide was observed in the concentration range 7 x 10(-8)-2.5 x 10(-6) M. Due to the presence of superoxide dismutase, hydrogen peroxide is partly regenerated and an amplification of the signal results, which explains the sensitivity.
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PMID:An enzymatic determination of hydrogen peroxide by using spectrophotometry. 142 21

The growth inhibition of the Streptococcus mutans group, including Streptococcus mutans, Streptococcus cricetus, Streptococcus rattus and Streptococcus sobrinus, on glucose by oxygen and the properties of reduced nicotinamide adenine dinucleotide (NADH) oxidase induced by oxygen, using a representative oxygen-tolerant strain, were examined. The growth response to oxygen varied among strains and correlated with the level of NADH oxidase activity in the cell extract. The induced synthesis of NADH oxidase as well as superoxide dismutase was affected by oxygen tension and energy sources. The induced NADH oxidase involved at least two types, major H2O-forming NADH oxidase and minor H2O2-forming NADH oxidase activity. In the presence of a scavenger of H2O2, pyruvate, the growth inhibition by oxygen in an oxygen-sensitive strain (GS5) was protected but not in another oxygen-sensitive strain (MT8148). The high level of induced H2O-forming NADH oxidase activity protected against oxygen toxicity.
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PMID:Reduced nicotinamide adenine dinucleotide oxidase involvement in defense against oxygen toxicity of Streptococcus mutans. 149 56

The purpose of this study was to develop a simple antioxidant screening assay for quantifying the protective effects of antioxidant enzymes, inhibitors and scavengers against extracellularly generated oxygen species on human skin fibroblast cytotoxicity. Different in vitro oxidative stresses have been studied: xanthine oxidase-hypoxanthine, flavin mononucleotide-NADH, and hydrogen peroxide. Cytotoxicity and protection were evaluated by two procedures: evaluation of the living cells using a colorimetric method (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide MTT), and ability of the viable cells to adherate and proliferate. Hypoxanthine-xanthine oxidase and H2O2 induced a dose dependent cytotoxicity only when we considered the delayed toxicity. The influence of the cell density was also investigated. The delayed toxicity was higher when cell density increased. One hundred percent protection against free radical cytotoxicity induced by the three systems were obtained with catalase (500 U/ml). When the oxidative stress used was H2O2 90-96% protection was obtained with deferoxamine an iron chelating agent that prevents iron catalysed radical reactions. Using the colorimetric method no significant protection was obtained when SOD was added before and during the stresses. Using the fibroblasts ability to proliferate SOD (10-150 micrograms/ml) reduced xanthine oxidase (20 U/l)-hypoxanthine (0.10-0.30 mM) or H2O2 (1-6 mM) cytotoxicity by 15-20%. SOD did not act as antioxidant when the applied stress was mediated by flavin. In this study we showed a paradoxical effect and the cytotoxicity of flavin-NADH system increased when we added SOD to the cell medium. This simple and reliable antioxidant screening assay required no costly or radioactive equipment.
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PMID:Development of a simple antioxidant screening assay using human skin fibroblasts. 150 88

A NADH oxidase has been purified from the extreme thermophile Thermus thermophilus HB8 by several chromatographic steps. The purified enzyme was essentially homogeneous as judged by gel electrophoresis under denaturing conditions and by determination of the N-terminal amino acids sequence. It is a monomeric flavin-adenine-dinucleotide-containing flavoprotein with an apparent molecular mass of 25 kDa and an 1:1 ratio of FAD to the polypeptide chain. The purified enzyme catalyzes the oxidation of reduced NADH or NADPH with the formation of H2O2. The apparent Km values for NADH and NADPH are 4.14 microM and 14.0 microM (pH 7.2 at room temperature), respectively, with a sixfold greater kcat/Km values for NADH compared to NADPH. The enzyme uses O2 as an electron acceptor in the presence of either FAD, riboflavin 5'-phosphate or riboflavin as cofactor. In addition, the enzyme is able to catalyze electron transfer from NADH to various other electron acceptors (methylene blue, cytochrome c, p-nitroblue tetrazolium, 2,6-dichloroindophenol and potassium ferricyanide), even in the absence of flavin shuttles. No significant inhibition of the NADH oxidoreductase activity by superoxide dismutase was observed with these artificial electron acceptors, indicating that electron transfer occurs mainly from NADH directly to the electron acceptors, not via O2- as an intermediate. The purified NADH oxidase exhibits highest activity at pH 5.0 and is stable at elevated temperatures of up to 80 degrees C.
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PMID:Purification and characterization of a NADH oxidase from the thermophile Thermus thermophilus HB8. 157 5


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