Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Erythrocytes are hemolyzed by myeloperoxidase, an H2O2-generating system (glucose + glucose oxidase; hypoxanthine + xanthine oxidase) and an oxidizable cofactor (chloride, iodide, thyroxine, triiodothyronine). The combined effect of chloride and either iodide or the thyroid hormones is greater than additive. Myeloperoxidase can be replaced by lactoperoxidase in the iodide-, thyroxine and triiodothyronine-dependent, but not in the chloride-dependent, systems. Hemolysis is is inhibited by the peroxidase inhibitors, azide and cyanide, and by catalase and is stimulated by superoxide dismutase when the xanthine oxidase system is employed as the source of H2O2. Hemolysis by the iodide-dependent system is associated with the iodination of erythrocyte components.
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PMID:Hemolysis and iodination of erythrocyte components by a myeloperoxidase-mediated system. 117 52

The interaction between milk xanthine oxidase (XO) and lactoperoxidase (LP) in model system and antimicrobial action of these enzymes on Escherichia coli 0-111 were studied. It was shown, that bacterial superoxide dismutase (SOD), which transforms O2-. (XO-reaction product) into H2O2 (substrate of LP), is necessary for binding of the reaction sequence: XO-->LP-->antimicrobial products. It is suggested, that these enzymes unite in the protective system in intestinal infections of newborns. Bacterial SOD in this case acts as the key factor, creating the system.
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PMID:[Free-radical mechanism of antimicrobial action of xanthine oxidase and lactoperoxidase]. 147 55

The formation and decay of intermediate compounds of horseradish peroxidase, lactoperoxidase, and myeloperoxidase formed in the presence of the superoxide/hydrogen peroxide-generating xanthine/xanthine oxidase system has been studied by observation of spectral changes in both the Soret and visible spectral regions and both on millisecond and second time scales. It is tentatively concluded that in all cases compound III is formed in a two-step reaction of native enzyme with superoxide. The presence of superoxide dismutase completely inhibited compound III formation; the presence of catalase had no effect on the process. Spectral data which indicate differences in the decay of horseradish peroxidase compound III back to the native state in comparison with compounds III of lactoperoxidase and myeloperoxidase are also presented.
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PMID:The reactions of horseradish peroxidase, lactoperoxidase, and myeloperoxidase with enzymatically generated superoxide. 254 42

Milk proteins in acid whey were separated into five fractions according to molecular size by gel filtration chromatography. The second peak, P2, contained proteins between approximately 250,000 and 100,000 daltons. Proteins in P2 were concentrated. After separation into albumins and globulins, each protein group was isolated by DEAE chromatography and hydrophobic interaction chromatography, Isolated albumin fractions were a yellow-colored protein of 89,000 daltons, an unidentified protein of 73,000 daltons, a beta-lactoglobulin of 18,300 daltons, and a red-colored protein of 87,000 daltons. Two types of globulin fractions were isolated: 1) a globulin fraction that coagulated in saturated sodium sulfate but did not coagulate when dialyzed against deionized water included a brown-colored protein of 150,000 daltons, and 2) a bovine serum albumin of 67,000 daltons with unidentified 170,000 and 30,000 daltons bands. A true globulin fraction contained a 77,000 dalton unidentified protein with several faint bands. The red-colored protein was identified as lactoferrin and the brown-colored protein as xanthine oxidase (EC 1.2.3.2.). A yellow-colored protein was concluded to be the denatured protein of contaminated lactoperoxidase (EC 1.11.1.7).
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PMID:Isolation of some minor milk proteins, distributed in acid whey from approximately 100,000 to 250,000 daltons of particle size. 337 95

Xanthine oxidase (XO) was demonstrated to be present in the teat canal and secretory tissue of the bovine mammary gland by histochemical techniques. Homogenates of these tissues were able to replace XO in an antibacterial assay with Streptococcus uberis. The action of XO on its substrate hypoxanthine was shown to provide an essential component for anti-streptococcal activity mediated by lactoperoxidase. A mechanism is proposed whereby the interaction of XO, lactoperoxidase and thiocyanate may provide antibacterial activity in the teat canal.
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PMID:Histochemical localization and possible antibacterial role of xanthine oxidase in the bovine mammary gland. 338 64

Two dermatophyte strains, Trichophyton quinckeanum and Trichophyton rubrum, were highly susceptible to in vitro killing by components of the H2O2-peroxidase-halide system. Both strains were, however, resistant to relatively high concentrations of reagent H2O2 or H2O2 enzymatically generated by glucose and glucose oxidase, KI, or lactoperoxidase (LPO) alone. Resistance to hydrogen peroxidase killing was found to be in part due to the presence of endogenous catalase in the fungi; susceptibility was increased by pretreatment of the fungi with a catalase inhibitor. Kinetic studies using small quantities of reagent or enzymatically generated H2O2 and LPO-KI showed that the system was lethal for both fungal strains within 1 min. Furthermore, using the glucose-glucose oxidase-LPO-KI system, it was shown that catalase, superoxide dismutase and histidine scavengers of H2O2, superoxide anion and singlet oxygen, respectively, prevented the killing of fungus, whereas scavengers of hydroxyl radicals such as benzoate and mannitol had no effect. T. quinckeanum was found to contain large quantities of superoxide anion, as judged by the nitroblue-tetrazolium test. Consequently, the xanthine (or hypoxanthine) and xanthine oxidase system in which the main product is superoxide anion had no toxic effect on the fungus. The high sensitivity of dermatophytes to killing by the H2O2-peroxidase-halide system active in polymorphonuclear neutrophils and macrophages may account in part for fungal toxicity in vivo.
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PMID:Susceptibility of Trichophyton quinckeanum and Trichophyton rubrum to products of oxidative metabolism. 361 Feb 10

The ability of human polymorphonuclear cells (PMN) to take up and destroy intracellular forms of Trypanosoma cruzi (AMA) was investigated as a part of our efforts to elucidate the mechanisms of clearing of these parasites from infected tissues. PMN were found to take up AMA and destroyed parasites were seen after 30 min of cell-parasite interaction. Under our experimental conditions, the rate of uptake of AMA by PMN was maximal during the first 30 min of interaction. AMA were found to be located and destroyed inside the phagolysosomal vacuoles of PMN. The parasite was never found outside these vacuoles despite electron microscopic examination of numerous preparations derived from several experiments. Intracellular destruction of AMA by PMN was visible by electron microscopy and could be monitored by measuring the release of 3H-labeled substances by PMN that had ingested radiolabeled AMA. PMN incubated after removal of unbound parasites destroyed over 90% of the ingested organisms within 3 hr and close to 99% after 12 hr. In cellfree systems, 44% of the AMA were destroyed in the presence of 10(-4) M H2O2 and all of the parasites died at 10(-3) M. Addition of lactoperoxidase and iodide resulted in 100% killing at 10(-5) M H2O2. These mechanisms appeared to be involved in the lysis of AMA by PMN since both H2O2 and peroxidase activity were demonstrated to be present in PMN vacuoles containing the parasite. Addition of NaN3, KCN (inhibitors of myeloperoxidase activity) or catalase (to decompose H2O2) caused a marked reduction in the extent of AMA killing by PMN. Xanthine oxidase was toxic for the AMA in the presence of acetaldehyde. This microbicidal activity was inhibited by catalase but not by heat-inactivated catalase or by reagents that scavenge the intermediate products of reduction of molecular oxygen, O - X 2, X OH, and 1O2. These results suggest that PMN have the potential of clearing AMA liberated in infected chagasic tissues and that parasite killing within the phagolysosomal vacuoles is mediated by myeloperoxidase activity and H2O2.
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PMID:Role of polymorphonuclear cells in Chagas' disease. I. Uptake and mechanisms of destruction of intracellular (amastigote) forms of Trypanosoma cruzi by human neutrophils. 630 64

The intrapulmonary instillation into rat lung of enzymes that generate oxygen metabolites results in acute lung injury. The injection of xanthine oxidase and xanthine produces acute lung injury that, in the presence of superoxide dismutase, but not in the presence of catalase, can be significantly diminished, suggesting that O2- has the capacity to injure the lung. Instillation of a generator of H2O2, namely glucose oxidase, will, in sufficient quantities, produce acute injury that is not neutrophil-dependent. When either a low dose of glucose oxidase alone or lactoperoxidase alone is employed, little lung injury occurs. However, instilling the combination of the two enzymes produces severe, acute injury that can be blocked in a dose-dependent manner by catalase, but not by superoxide dismutase. Purified human leukocytic myeloperoxidase, but not horseradish peroxidase, will substitute for lactoperoxidase in the model of lung injury. The lung damaging effects of these enzymes cannot be attributed to the presence of contaminating proteases. Acute lung injury produced by the instillation of glucose oxidase and lactoperioxidase progresses to interstitial fibrosis. These studies represent a direct application of generators of oxygen metabolites to the in vivo induction of lung injury. The data suggest that rat lung is susceptible to injury by a variety of oxygen metabolites, including O2-, H2O2 and its lactoperoxidase or myeloperoxidase-produced derivatives. The studies also indicate that lung injury produced by oxygen metabolites can result in interstitial pulmonary fibrosis.
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PMID:In vivo damage of rat lungs by oxygen metabolites. 689 54

A new type of antibody-enzyme conjugate was made, and its possible application to Candida infection was studied. Both lactoperoxidase and xanthine oxidase were conjugated to specific antibody against Candida albicans. In vitro microbiocidal activity of the new antibody-enzyme conjugate, when incubated together with xanthine and minute amount of halides, showed a remarkable level of candidacidal ability. When the new antibody-enzyme conjugate was given to Candida-infected mice, followed by injecting xanthine and a minute amount of halides, about 50% of these heavily infected mice survived, whereas all control nontreated mice died. These data suggest that the further eleboration of this new antibody-enzyme conjugate might lead us to improve our therapeutic methods of clinical medicine.
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PMID:New type of antibody-enzyme conjugate which specifically kills Candida albicans. 699 24

Susceptibility to oxidative stress is increased in erythrocytes of patients with beta-thalassaemia due to the free alpha-chain pool and to the excess of iron. We have investigated the effect of L-propionylcarnitine concentrations on oxidative stress determined by lactoperoxidase-hydrogen peroxide-iodide and by xanthine oxidase-acetaldehyde on erythrocytes of patients with beta-thalassaemia (major and intermedia). L-propionyl carnitine protects the erythrocytes from oxidative stress as measured by cell lysis. The protection is concentration-dependent. L-propionyl carnitine also stabilizes the cell membranes in which a latent peroxidative damage has been produced. These data suggest that L-propionyl carnitine may prove beneficial in protecting in vivo patients in which peroxidative damage of cell structure is increased as in the case of beta-thalassaemic patients.
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PMID:Protection of beta-thalassaemic erythrocytes from oxidative stress by propionyl carnitine. 785 33


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