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)

Cultures of Methylomonas J, an aerobic methylotrophic bacterium, were grown both in Mn-rich and Fe-rich media. Crude extracts of the cultures from the Mn-rich and Fe-rich medium showed a specific activity of 12.2 and 0.6 units/mg by a cytochrome c-xanthine oxidase method and 19.4 and 1.3 units/mg by an ESR method, respectively. We isolated Mn-SOD and Fe-SOD from the bacteria grown in the Mn-rich and Fe-rich mediums, respectively. Specific activity and metal contents of the Mn-enzyme were 2,250 units/mg/g-atom Mn and Mn = 0.98 and Fe = 0.12 (g-atoms/mol dimer), while those of the Fe-enzyme were 61 units/mg/g-atom Fe and Mn = 0.02 and Fe = 1.08. No difference of physicochemical properties of the Fe- and Mn-enzymes were detected. Furthermore, enzyme activity was restored by dialysis of an apoprotein obtained from the Fe-enzyme with either manganese sulfate or ferrous ammonium sulfate.
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PMID:Isolation of Mn-SOD and low active Fe-SOD from Methylomonas J; consisting of identical proteins. 190 19

The perfused isolated kidney is a partial ischemic system that is characterised by glomerular proteinuria and release of glomerular heparan sulfate. Metabolic changes associated with the levels of glutathione, xanthine oxidase and glyceraldehyde 3-dehydrogenase indicated that oxygen radical metabolites were being produced during the perfusion. We have demonstrated that a mixture of oxygen metabolite scavengers containing mannitol, superoxide dismutase and catalase included in the perfusion medium significantly reduced protein excretion. Similar results were obtained with the administration of allopurinol to the rat 24h prior to kidney removal and allopurinol in the perfusion medium. [35S]Heparan sulfate loss from the glomerulus was totally inhibited by the scavenger mixture. These results suggest that reactive oxygen metabolites may be involved in damage to renal capillaries, specifically to heparan sulfate proteoglycan, which leads to proteinuria as a result of partial ischemia produced during perfusion.
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PMID:The inhibitory action of oxygen radical scavengers on proteinuria and glomerular heparan sulphate loss in the isolated perfused kidney. 214 Dec 55

Myofibrils from rat hearts were prepared in conditions maintaining their redox state, and their sulfhydryl groups were measured using a solution of urea and sodium dodecyl sulfate (SDS) as denaturant. The sulfhydryl content was 92 n mol/mg of protein, indicating that cysteins are in reduced form. In the presence of superoxide radicals generated in vitro with purine and xanthine oxidase, the myofibrillar sulfhydryl groups were oxidized.
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PMID:[Assay of sulfhydryl groups in cardiac myofibrillar proteins: effect of oxygen radicals in vitro]. 215 Jul 78

Trolox, a hydrophilic analogue of alpha-tocopherol, was reported to scavenge peroxyl radicals better than vitamin E in sodium dodecyl sulfate micelles and in liposomes. However, it was not known if Trolox protects human cells against oxyradical damage or if it acts as an antioxidant there. Here we demonstrate that Trolox prolonged substantially the survival of human ventricular myocytes and hepatocyte against oxyradicals generated with xanthine oxidase plus hypoxanthine, and prevented lysis of red cells exposed to an azo-initiator (2,2'-azo-bis(2-amidinopropane) HCl). Note that Trolox did not inhibit xanthine oxidase. In each cell type, the protection by Trolox was dose dependent and surpassed those given by such water-soluble antioxidants as ascorbic acid, superoxide dismutase, and (or) catalase, each examined at or near its optimal level in the same system. Using hepatocytes as a model, we further observed that Trolox reduced markedly the quantity of phospholipid conjugated dienes (a chemical imprint of oxyradical damage) in cells despite their exposure to oxyradicals. These data suggested that Trolox behaves as an antioxidant in cells as illustrated in hepatocytes.
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PMID:The cytoprotective effect of Trolox demonstrated with three types of human cells. 226 14

During the reductive process in the tissues, the aerobes generate a number of oxidants. Unless these oxidants are reduced, oxidative damage and cell death would occur. Oxidation of plasma membrane lipids leads to autocatalytic chain reactions which eventually alter the permeability of the cell. The role of oxidative damage in the pathophysiology of diabetic complications and ischemic reperfusion injury of myocardium, especially the changes in the channel activity which may lead to arrhythmia have been studied. Hyperglycemia activates aldose reductase which could efficiently reduce glucose to sorbitol in the presence of NADPH. Since NADPH is also aldose required by glutathione reductase for reducing oxidants, its diversion would lead to membrane lipid oxidation and permeability changes which are probably responsible for diabetic complications such as cataractogenesis, retinopathy, neuropathy etc. Antioxidants such as butylated hydroxy toluene (BHT) and also reductase inhibitors prevent or delay some of these complications. By using patch-clamp technique in isolated frog myocytes, we have shown that hydroxy radicals generated by ferrous sulfate and ascorbate as well as lipid peroxides such as t-butyl hydroperoxide facilitate the entry of Na+ by oxidizing Na+-channels. Increased intracellular Na+ leads to an increase in Na+/Ca2+ exchange. The increased Na+ concentration by itself may produce electrical disturbance which would result in arrhythmia. Increased Ca2+ may affect proteases and may help in the conversion of xanthine dehydrogenase to xanthine oxidase, consequently increased production of super oxide radicals. Increased membrane lipid peroxidation and other oxygen free-radical associated membrane damage in myocytes has been demonstrated.
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PMID:The effect of oxidants on biomembranes and cellular metabolism. 251 41

The detergent-induced amplification of lucigenin-dependent chemiluminescence of O2-, generated by xanthine oxidase or microsomal NADPH oxidase was studied. An assay system is described which is at least 10 times more sensitive than normal lucigenin-dependent chemiluminescence due to the amplification by high concentrations of octylphenylpolyethylene glycol (Triton X-100). Compared to the superoxide dismutase-sensitive reduction of acetylated cytochrome c, a 3750-fold lower amount of microsomal protein was necessary to produce an O2- signal 10-fold above the background. In contrast to cytochrome c reduction, detergent-amplified chemiluminescence of lucigenin was completely inhibited by superoxide dismutase and therefore more selective for O2-. The membrane-bound and Triton X-100-solubilized NADPH oxidase from microsomes of macrophages was activated by ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid and inhibited by Ca2+ and sodium dodecyl sulfate. The membrane-bound enzyme showed a Km value of 1.35 microM, which decreased to 0.95 microM after the addition of 12% (g/g) Triton X-100. The Km and Vmax values of soluble xanthine oxidase were not influenced by Triton X-100, indicating that the enzyme activities were not impaired by the high concentrations of detergent.
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PMID:Detergent-amplified chemiluminescence of lucigenin for determination of superoxide anion production by NADPH oxidase and xanthine oxidase. 283 20

The effect of superoxide radical on the azide-insensitive ATP-dependent Ca2+-transport by a plasma membrane (PM)-enriched fraction (F2) and an endoplasmic reticulum (ER)-enriched fraction (F3) isolated from pig coronary artery was examined using xanthine oxidase plus xanthine to generate superoxide ions. A preincubation with xanthine oxidase plus xanthine at 37 degrees C preferentially inactivated the oxalate-stimulated Ca2+ uptake by the F3 fraction rather than the phosphate-stimulated uptake by the F2 fraction, indicating that the Ca2+ pump in the ER was more susceptible to this free radical. The inactivation of the Ca2+ uptake depended on the concentrations of xanthine oxidase and xanthine in the preincubation mixture as well as on the preincubation time. Furthermore, the inclusion of superoxide dismutase in the preincubation mixture prevented the inactivation. Thus the inactivation was caused by superoxide radical. Preincubation with xanthine oxidase plus xanthine, however, altered the half-life of efflux of Ca2+ from these vesicles only marginally. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the F3 fraction showed formation of a Ca2+-dependent acid stable phosphoenzyme at 0 degree C predominantly at a protein band corresponding to 100 kDa. The level of the 100-kDa acylphosphate intermediate was inhibited in parallel with the inhibition of the Ca2+ uptake by preincubation with xanthine oxidase plus xanthine. We conclude that superoxide radical inactivates the ER Ca2+ transport by lowering the level of the phosphoenzyme.
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PMID:Effect of superoxide radical on Ca2+ pumps of coronary artery. 284 93

Senescent cell antigen (SCANT) is a "neo antigen" that appears on the surface of normal old cells and initiates IgG binding and cellular removal. To investigate the mechanism by which SCANT is generated from its parent molecule, band 3, we subjected intact human erythrocytes to treatments that have been reported to result in changes in band 3 and/or to mimick aging in vitro. The validity of these treatments as model systems for erythrocyte aging was evaluated using a "red cell aging panel" that provides a biochemical profile of a senescent red cell. Treatments were assessed for their ability to induce in vitro the following changes observed in normal erythrocytes aged in vivo: 1 increased breakdown of band 3 as detected by immunoblotting, 2 decrease in anion transport efficiency as detected with a sulfate self-exchange assay, 3 decrease in total glyceraldehyde 3-phosphate dehydrogenase activity with an increase in membrane-bound activity, and 4 increase in the binding of autologous IgG as detected with a protein A binding assay. Neither incubation with the free radical-generating xanthine oxidase/xanthine system, nor treatment with malondialdehyde, and end product of free radical-initiated lipid (per)oxidation, results in age-specific changes. Loading of the cells with calcium and oxidation with iodate results in increased breakdown of band 3, but does not lead to increased binding of autologous IgG. Only erythrocytes that have been stored for 3-4 weeks show the same structural and functional changes as observed during aging in vivo.
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PMID:Erythrocyte aging: a comparison of model systems for simulating cellular aging in vitro. 317 56

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 dehydrogenase (EC 1.2.1.37) was purified approximately 1000-fold from liver homogenates of adult male Sprague-Dawley rats. Enzyme recovery was good (greater than 20% of the starting activity was obtained), and the homogeneously pure enzyme had a molecular mass of approximately 300,000 Da. The purified protein exhibited a specific activity of 2470 units/mg protein and spectral properties identical to those of the best preparations of this enzyme reported by other investigators. Routine preparations of this enzyme also possess higher dehydrogenase:oxidase ratios (typically between 5 and 6) than do other xanthine dehydrogenase preparations so far reported in the literature. Maximum dehydrogenase:oxidase ratios, greater than 10, could be obtained from this procedure if only peak dehydrogenase fractions from the chromatography columns were saved. The present small-scale purification method, which can be completed in 48-60 h, utilizes ammonium sulfate fractionation, Sephadex G-200 column chromatography, Blue Dextran-Sepharose column chromatography, and preparative gel electrophoresis.
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PMID:Purification of xanthine dehydrogenase from rat liver: a rapid procedure with high enzyme yields. 347 1


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