Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.3 (ascorbate oxidase)
 778 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The use of methylene blue (MB) to estimate dilution of epithelial lining fluid, which occurs during bronchoalveolar lavage (BAL), is complicated by loss of this redox dye from the air spaces. The rate of MB uptake from the air spaces of isolated rat lungs and the effects of oxidation and reduction on this process were investigated in this study. Movement of MB from the air spaces to perfusate was compared with the corresponding transport of 125I-labeled albumin, [14C]-dextran, 99mTc-labeled diethylenetriaminepentaacetate, [3H]-sucrose, and 3H2O. By the end of 2 min, MB concentrations in the BAL had fallen by 58 +/- 4% (SE; n = 11) and 3H2O by 78 +/- 2% (n = 13), whereas concentrations of the other indicators decreased by approximately 6%. All but 10% of the 3H2O lost from the air spaces was found in the perfusate, whereas 19% of the lost MB was not recovered in the perfusate, suggesting retention of MB in the pulmonary tissues. Absorption of MB from the air spaces was slowed by 20% when the lungs were left unperfused, and absorption was accelerated threefold by reduction of MB to leukomethylene blue with Na2S2O4. In contrast, MB losses from the air space were slowed by the oxidizing agent K3Fe(CN)6 and by addition of superoxide dismutase or ascorbic oxidase. It is therefore possible that ascorbic acid and O2- entering the air spaces reduce MB to the uncharged leuko form. Lowering the pH of the BAL fluid to 3.5 also slowed MB reabsorption. This suggests that acid aspiration may stimulate release of oxidants into the air spaces.
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PMID:Reduction and uptake of methylene blue from rat air spaces. 783 53

The effect of ascorbic acid on Ca2+ uptake in cultured rat astrocytes was examined in the presence of ouabain and monensin, which are considered to drive the Na(+)-Ca2+ exchanger in the reverse mode. Ascorbic acid at 0.1-1 mM inhibited Na(+)-dependent Ca2+ uptake significantly but not Na(+)-dependent glutamate uptake in the cells, although the inhibition required pretreatment for more than 30 min. The effect of ascorbic acid on the Ca2+ uptake was blocked by simultaneous addition of ascorbate oxidase (10 U/ml). Na(+)-dependent Ca2+ uptake was also inhibited by isoascorbate at 1 mM but not by ascorbate 2-sulfate, dehydroascorbate, and sulfhydryl-reducing reagents such as glutathione and 2-mercaptoethanol. The inhibitory effect of ascorbic acid was observed even in the presence of an inhibitor of lipid peroxidation, o-phenanthroline, or a radical scavenger, mannitol, and the degrading enzymes such as catalase and superoxide dismutase. On the other hand, the inhibitory effect was not observed under the Na(+)-free conditions that inhibited the uptake of ascorbic acid in astrocytes. When astrocytes were cultured for 2 weeks in a medium containing ascorbic acid, the content of ascorbic acid in the cells was increased and conversely Na(+)-dependent Ca2+ uptake was decreased. These results suggest that an increase in intracellular ascorbic acid results in a decrease of Na(+)-Ca2+ exchange activity in cultured astrocytes and the mechanism is not related to lipid peroxidation.
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PMID:Intracellular ascorbic acid inhibits the Na(+)-Ca2+ exchanger in cultured rat astrocytes. 789 Oct 80

Zitter rats develop a genetic spongiform encephalopathy characterized by edematous changes in their brains. In order to elucidate the involvement of reactive oxygen species in this process we examined age-related alterations of the activities of the enzymes which metabolize reactive oxygen species. Activities of superoxide dismutase (SOD), D-amino acid oxidase (D-AAO), glutathione peroxidase (GSH-Px) and catalase in the brain and the liver of zitter rats are compared with those of control SD/J rats. In the brain of adult zitter rats which show degenerative changes, significantly enhanced activities of SOD and D-AAO were obtained, whereas activity of catalase was lower than that of the SD/J rats. Prominent abnormalities in catalase and D-AAO but not in SOD activity were demonstrated before or at the same time as the appearance of the morphological vacuolation in the brain of suckling zitter rats. There was no difference in GSH-Px activity between the brains from zitter and SD/J rats. These results suggest that the alteration of hydrogen peroxide (H2O2)-metabolism in microperoxisomes may play an important role in the initiation of degenerative changes in the brain of zitter rats. Enhanced SOD activity observed in the brain of adult zitter rats may be a compensatory response to the high superoxide anion produced in the course of cell damage caused by the H2O2 stagnation. Also, more SOD might produce more H2O2.
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PMID:Antioxidant enzymes in the brain of zitter rats: abnormal metabolism of oxygen species and its relevance to pathogenic changes in the brain of zitter rats with genetic spongiform encephalopathy. 798 77

Quantitation of the superoxide radical and its related metabolites in vivo is practically difficult predominantly because of their short biological half-lives. Though oxidized cytochrome c (cyt c) has been used for determining superoxide radicals in vitro, it cannot be used for in vivo analysis because of its low specificity as an electron acceptor and rapid disappearance from the circulation. To measure superoxide radicals and related metabolites in normal and pathologic subjects, we have synthesized a cyt c derivative (SMAC) with prolonged half-life in the circulation (T1/2 = 130 min) by conjugating acetylated cyt c with poly(styreneco-maleic acid) butyl ester (SM). An SM-conjugated superoxide dismutase (SM-SOD) with prolonged in vivo half-life was also synthesized. When injected intravenously to the rat, SMAC was rapidly reduced in the circulation of normal rats. The rate of SMAC reduction was markedly increased by intravenous administration of menadione, a compound capable of redox cycling and generating superoxide. The rate of SMAC reduction was not inhibited by a large dose of SM-SOD (27,000 unit/kg) in both normal and menadione-treated animals. The rate of SMAC reduction also increased in animals which were administered alloxan, a diabetogenic agents. In contrast to the experiments with menadione, the alloxan-enhanced reduction of SMAC was significantly inhibited by SM-SOD. Kinetic analysis using ascorbate oxidase suggested that ascorbyl radical was principally responsible for the SM-SOD-insensitive reduction of SMAC. Streptozotocin, another diabetogenic agent, failed to increase the rate of SMAC reduction. Thus, the effect of streptozotocin on the redox state of animals and the mechanism of its diabetogenic action might differ from those of alloxan. Combined use of SMAC and SM-SOD might permit quantitative studies on the occurrence of ascorbyl and superoxide radicals in the circulation of animals challenged with oxidative stress.
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PMID:Determination of superoxide and ascorbyl radicals in the circulation of animals under oxidative stress. 813 44

BITO decreased the intesity of lipid peroxdation; intensity of intravascular hemolyses at termal trauma. It increased oxidability of lipids of blood serum, liver and brain. Its antioxidative activity may be explainde by the presence of ceruloplasmin, posessing antioxidative activity may be explained by the presence of ceruloplasmin, posessing ascorbate oxidase, ferroxidase and superoxide dismutase activities. Lipid components of the fraction play a role of "structural antioxidants".
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PMID:[In vitro effect of BITO preparation, ceruloplasmin, transferrin, and essentiale on the intensity of lipid peroxidation during thermal injury]. 914 95

Free radical scavenging activities of water-soluble extracts from some natural sources, health foods, and antioxidant substances were measured using the JES-FR30 JEOL spectrometer. The objective was to develop a standardized method whereby comparison could be made between the radical scavenging activities of complex mixtures. Scavenging of hydroxyl radical was determined using DMPO. Activity was calibrated using a standard material, L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H -1- benzopyran-6yl-hydrogen phosphate] potassium salt (EPC-K1), an analog of vitamin C and vitamin E which is water soluble and stable at room temperature. The order of greatest hydroxyl radical scavenging activity was green tea extract, pine bark extract (Pycnogenol), Ginkgo Biloba extract (EGb 761), a flavonoid blend of several fruit and vegetable extracts (GNLD), and Bio-Normalizer (Sun-O Corp). Activity was determined after treatment of samples with ascorbic acid oxidase. This treatment revealed the presence of ascorbate in some natural extracts and commercial preparations. The pine bark extract was the most heat resistant and had ascorbate-like activity in the preparations. Scavenging of superoxide anion was determined using the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), and analyzed by comparison with a standard curve made with superoxide dismutase. Comparison of the water solubilized components of natural source antioxidants showed that filtrates fractionated using centrifuge type Millipore filter tubes (M.W. < 100,000; M.W. < 10,000) also had almost the same SOD-like activity. Samples were also treated with ascorbate oxidase or by heating (100 degrees C for 10 min). The order of activity, from greatest to least, was Ginkgo biloba extract EGb 761, pycnogenol, beta-catechin, tea and BioNormalizer.
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PMID:Hydroxyl and superoxide anion radical scavenging activities of natural source antioxidants using the computerized JES-FR30 ESR spectrometer system. 919 83

Radical scavenging by reconstituted lyophilized powders of water extracts from 16 common vegetables was measured using electron spin resonance (ESR) with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), hydroxyl radicals, (.OH) or superoxide anion radicals (O2.-), as DMPO-OH or DMPO-OOH spin adducts. On a dry weight basis, eggplant, and red, yellow and green bell pepper extracts showed potent superoxide anion radical scavenging activities (SOD-like activities). Ascorbate oxidase- or heat-treatments, decreased SOD-like activities in bell pepper extracts suggesting that ascorbate accounts for much of their free radical scavenging activity. Eggplant epidermis extract exhibited the most potent hydroxyl radical scavenging and SOD-like activities. Eggplant SOD-like activity did not decrease after ascorbate oxidase treatment, but decreased following ultrafiltration demonstrating that SOD-like activity is partially due to high molecular weight substances. Nasunin, an anthocyanin in eggplant epidermis, showed markedly potent superoxide anion radical scavenging activity, while it inhibited hydroxyl radical generation probably by chelating ferrous ion.
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PMID:Superoxide anion and hydroxyl radical scavenging activities of vegetable extracts measured using electron spin resonance. 1041 Feb 44

Five peptides containing (His-X2)-His or (His-X3)-His motifs have been designed and synthesized to coordinate Cu(II). Structural information was obtained by various spectroscopic techniques and was used as constraint to search for local conformational energy minima by molecular mechanics. Thermodynamic stability constants of the Cu(II) chelates was obtained by 19F-NMR. The synthesized Cu(II)-peptide chelates were tested as catalysts of some important red-ox processes occuring in biological systems, in particular oxidation of ascorbate and dismutation of superoxide ion. The catalytic efficiency of the five chelates was much lower than that of ascorbate oxidase. On the contrary, two of them showed kinetic constants for superoxide dismutation about one order of magnitude lower than that of the enzyme Cu,Zn superoxide dismutase. In both cases, the catalytic properties were dependent on the peptide sequence. The relationships between structure and activity are discussed to find the structural parameters crucial for catalytic activity that can be modulated by appropriate design and synthesis of the peptides.
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PMID:Enzyme mimics complexing Cu(II) ion: structure-function relationships. 1060 94

The effects of superoxide anion generators, the nitric oxide (NO) scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoine-1-oxyl 3-oxide (carboxy-PTIO), the specific guanylate cyclase inhibitor 1H-[1,2,4]-oxadiazole-[4,3-a]-quinoxalin-1-one (ODQ), and thiol modulating agents were investigated on relaxations induced by nitrergic stimulation and exogenous NO addition in the sheep urethra. Methylene blue (MB, 10 microM), pyrogallol (0.1 mM) and xanthine (X, 0.1 mM)/xanthine oxidase (XO, 0.1 u ml(-1)) inhibited NO-mediated relaxations, without affecting those induced by nitrergic stimulation. This resistance was not diminished following inhibition of endogenous Cu/Zn superoxide dismutase (Cu/Zn SOD) with diethyldithiocarbamic acid (DETCA, 3 mM), which almost abolished tissue SOD activity. Carboxy-PTIO (0.1 - 0.5 mM) inhibited NO-mediated relaxations but had no effect on responses to nitrergic stimulation, which were not changed by treatment with ascorbate oxidase (2 u ml(-1)). Relaxations to NO were reduced, but not abolished, by ODQ (10 microM), while nitrergic responses were completely blocked. The thiol modulators, ethacrynic acid (0.1 mM), diamide (1.5 mM), or 5,5'-dithio-bis (2-nitrobenzoic acid) (DTNB, 0. 5 mM), and subsequent treatment with dithiothreitol (DTT, 2 mM) had no effect on responses to nitrergic stimulation or NO. In contrast, N-ethylmaleimide (NEM, 0.2 mM) markedly inhibited both relaxations. L-cysteine (L-cys, 0.1 mM) had no effect on responses to NO, while it inhibited those to nitrergic stimulation, in a Cu/Zn SOD-independent manner. Our results do not support the view that the urethral nitrergic transmitter is free NO, and the possibility that another compound is acting as mediator still remains open. British Journal of Pharmacology (2000) 129, 53 - 62
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PMID:Effects of superoxide anion generators and thiol modulators on nitrergic transmission and relaxation to exogenous nitric oxide in the sheep urethra. 1069 2

1. This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO(-)) released upon the decomposition of Angeli's salt. 2. Our results show that copper ions (from CuSO(4)) catalyze the rapid and efficient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1 - 100 microM) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from S-nitroso-N-acetyl-D,L-penicillamine (SNAP). 3. Experiments with ascorbate (1 mM), which reduces Cu(2+) ions to Cu(+), and with the Cu(2+) chelators, EDTA and cuprizone, and the Cu(+) chelator, neocuproine, each at 1 mM, suggest that the oxidation is catalyzed by copper ions in both valency states. 4. Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less efficient than CuSO(4) in catalyzing the formation of nitric oxide from nitroxyl, while FeSO(4), FeCl(3), MnCl(2), and ZnSO(4) were inactive. 5. Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30 u ml(-1), respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10 u ml(-1)) and tyrosinase (250 u ml(-1)) were inactive. 6. Our findings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive.
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PMID:Oxidation of nitroxyl anion to nitric oxide by copper ions. 1099 31


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