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)

1. In vivo 59Fe absorption from intrinsically labelled Fe-containing fractions of liver and blood were measured in rats by intragastric dosing. All rats were fed on a low-Fe diet for 3 d before dosing in order to standardize the Fe status of the intestinal mucosal cells. 2. An increase in digestion time from 2 to 12 h increased 59Fe absorption (P less than 0.01) from all fractions except ferritin. 3. Fe-deficient rats when compared with essentially Fe-replete rats showed decreased gastric retention for all fractions, but increased 59Fe absorption over 2 h only from ferritin. Ferritin showed several unusual absorption characteristics. 4. Dietary tungsten supplementation of Fe-deficient rats reduced the ferroxidase activity of intestinal mucosal xanthine oxidase. In addition, gastric retention and 59Fe absorption (P less than 0.05) from all fractions were increased.
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PMID:Effects of dietary iron deficiency and tungsten supplementation on 59Fe absorption and gastric retention from 59Fe compounds in rats. 275 11

The effect of peroral administration of xylitol on the absorption of iron and the activities of xanthine oxidase (EC 1.2.3.2) and ferroxidase in rat duodenal wall was studied. Adult male rats were given the basal diet containing 200 g xylitol/kg or the same diet containing no added carbohydrates for 8 weeks. Both feeding groups comprised twelve animals. Xylitol significantly increased serum and liver Fe concentrations with a concomitant, significant increase in the duodenal xanthine oxidase activities, but caused a marginal increase in the duodenal ferroxidase activities. In vitro, sugar alcohols reduced the binding rate of Fe to transferrin. The xylitol-induced increase of Fe absorption may involve the following mechanism: the high intraluminal xylitol concentration of the xylitol-fed rats keeps Fe in the form of a soluble complex for a prolonged period of time, due to the slow absorption of xylitol. The polyol-Fe complex in turn induces xanthine oxidase and ferroxidase formation.
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PMID:Duodenal xanthine oxidase (EC 1.2.3.2) and ferroxidase activities in the rat in relation to the increased iron absorption caused by peroral xylitol. 384 Jun 96

Exposure of human caeruloplasmin, an acute phase protein with antioxidant properties, to a mixture of xanthine/hypoxanthine and xanthine oxidase as a source of reactive oxygen intermediates decreased its ferroxidase and ascorbate oxidase activities and its ability to inhibit lipid peroxidation. Immunological reactivity was also altered. Exposure to hydrogen peroxide mimicked these effects. Exposure to low-intensity u.v. irradiation depressed caeruloplasmin's ability to inhibit iron-catalysed hyaluronic acid degradation. The results may explain the mechanism of the observed inactivation of caeruloplasmin within human rheumatoid synovial fluid.
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PMID:Action of free radical generating systems upon the biological and immunological properties of caeruloplasmin. 654 84

Low density lipoproteins are highly sensitive to oxidation by copper salts, and such peroxidation is accompanied by macrophage scavenger receptor recognition. This study shows that fresh human atherosclerotic material (aneurysms and endarterectomies) can contain detectable amounts of redox active iron and copper that is chelatable from tissue homogenates. Such material is often prooxidant towards lipid peroxidation and deoxyribose degradation. Aneurysms and endarterectomies contain ferroxidase 1 activities, whereas only in aneurysms could caeruloplasmin be immunologically detected. Ferroxidase 2 activity, characteristic of a copper-oxidised lipoprotein complex, could not, however, be detected in any of the atherosclerotic samples. A third ferroxidase activity, attributable to xanthine oxidase, was present in several aneurysms and endarterectomies.
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PMID:Prooxidant iron and copper, with ferroxidase and xanthine oxidase activities in human atherosclerotic material. 763 10

Xanthine oxidase exhibits ferroxidase activity and previously has been shown to catalyze the oxidative incorporation of iron into apotransferrin, the iron transport protein of plasma. These studies demonstrate that xanthine oxidase also efficiently promotes the oxidative incorporation of iron into apoferritin, the major iron storage protein of vertebrates, and that the ferroxidase activity of intestinal xanthine oxidase could be important in determining the fraction of iron within the intestinal mucosa cell partitioned to ferritin versus the iron that remains in a transient pool for rapid transport to plasma.
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PMID:Xanthine oxidase: an efficient promoter of the iron loading of apoferritin. 795 Oct 57

Exposure of cells to oxygen radicals results in cellular injury and protein oxidation. Ceruloplasmin is a plasma antioxidant that increases in concentration during inflammation. Therefore, the ability of ceruloplasmin to protect endothelial cells from neutrophil-mediated injury was investigated. The inhibition of protein oxidation by ceruloplasmin was also examined in neutrophil and endothelial cell proteins by analysis of carbonyl formation. In addition, the iron oxidation state was measured to determine the effect of ceruloplasmin ferroxidase activity in oxygen-radical generating systems. Ceruloplasmin significantly (p < .01) inhibited neutrophil-mediated cytotoxicity of endothelial cells by 48%. Carbonyl formation in phorbol myristate acetate (PMA)-stimulated neutrophil proteins was also significantly (p < .01) reduced by ceruloplasmin from 0.172 +/- 0.028 to 0.086 +/- 0.004 mole carbonyl/mole protein. Even though ceruloplasmin itself had a threefold increase in carbonyl formation (0.452 +/- 0.010 vs. 0.146 +/- 0.018 mole carbonyl/mole protein) in the presence of PMA-stimulated compared with unstimulated neutrophils, no loss of functional activity was detected. In xanthine oxidase-treated endothelial cells, ceruloplasmin significantly (p < .05) reduced carbonyl formation from 0.132 +/- 0.010 to 0.097 +/- 0.009 mole carbonyl/mole protein. Ceruloplasmin also significantly (p < .01) oxidized iron when added to PMA-activated neutrophils, thereby decreasing Fe(II) from 98 +/- 8 to 7 +/- 2 microM. Similarly, ceruloplasmin added to xanthine oxidase/hypoxanthine reactions resulted in significant (p < .01) iron oxidation, decreasing Fe(II) from 99 +/- 1 to 15 +/- 3 microM. The ability of ceruloplasmin to protect both endothelial cells and endogenous neutrophil and endothelial cell proteins from oxidative injury suggests that it may be important in regulating cellular and protein damage by oxygen radicals during inflammation.
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PMID:Ceruloplasmin inhibits carbonyl formation in endogenous cell proteins. 842 18

Ceruloplasmin (CP), an important serum antioxidant, is a blue copper glycoprotein with ferroxidase and oxidase activities. Among other physiological actions, plasma CP was shown to protect isolated rat hearts and cultured P19 neurons exposed to oxidative stress conditions, raising the possibility of using this protein in the treatment of cardiac and neuronal diseases related to oxidative damage. However, since therapeutic applications of CP must be compatible with restrictions in the administration of blood derivatives to humans, there is a need to produce the protein by genetic engineering. To help in the choice of adequate expression systems, we undertook this study to determine if the carbohydrate moiety on the protein is essential for its functions. CP was completely deglycosylated using N-glycosidase F under nondenaturing conditions. Deglycosylated CP was found to retain most of the conformational, antioxidant, and enzymatic properties of the native protein in vitro. Moreover, both forms of the protein had similar cardioprotective and neuronoprotective effects against oxidative stress as evaluated with isolated rat hearts undergoing ischemia-reperfusion and with cultured P19 neurons exposed to xanthine-xanthine oxidase. The data thus indicate that the carbohydrate moiety of CP is not essential for its enzymatic and protective actions. Accordingly, even the use of expression systems that do not glycosylate mammalian proteins could provide a recombinant CP that retains its therapeutic potential.
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PMID:Deglycosylated ceruloplasmin maintains its enzymatic, antioxidant, cardioprotective, and neuronoprotective properties. 1152 18

In the neonatal period, there is a high iron load, while both the level and molar oxidase activity of ceruloplasmin are low. On the other hand, the neonatal xanthine oxidase (XO) activity is higher than later in life and XO has a significant iron-oxidizing capacity. We therefore studied the physiological contribution of XO to the ferroxidase activity of the plasma in 20 full-term newborn infants. Ferroxidase activity was measured spectrophotometrically, with Fe++ as substrate. The uric acid formed by XO was assayed by means of HPLC, with electrochemical detection. The total ferroxidase activity in the plasma was about one-fourth of the adult level and rapidly increased doubling within 3 days after birth. About 90% of the plasma ferroxidase activity was due to ceruloplasmin, the remainder being accounted for by ferroxidase II. The XO activity underwent a 30% (statistically non-significant) elevation at 24 h, though ferroxidase activity attributable to XO was not detected at any time. Accordingly, XO does not seem to add substantially to the total iron-oxidizing capacity of the plasma in the neonatal period. The high molar ferroxidase activity is probably of importance at the endothelial cell surface.
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PMID:Ferroxidases and xanthine oxidase in plasma of healthy newborn infants. 1176 13

Iron is one of the most important essential metal ions of which significance is well known for ages. This element is a key moiety of several enzymes in iron containing heme or nonheme form and transfer and storage protein, hemoglobin and myoglobin. Several membrane carriers of iron have already been identified. The redox state of iron is determined by xanthine oxidase, cytochromes and Hp or ceruloplasmin and ferroxidase activity of apo-ferritin, respectively. Some vitamins (C, B2-, B3-, B6-, B12) play also a role in the metabolism of iron. The iron content of cells of the organs is well regulated by the iron homeostasis. Iron has a significant role in the immune system by producing oxygen containing free radicals. Anaemia induced by iron deficiency may cause a challenge concerns for pregnant women, babies and adolescent, primarily.
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PMID:[Physiologic and pathologic role of iron in the human body. Iron deficiency anemia in newborn babies]. 1550 4

The MmcO protein of Mycobacterium tuberculosis is a membrane-associated multicopper oxidase. Its natural substrate(s) and its role in pathogenesis are not well characterized. A recent report proposes that MmcO contributes to copper resistance in M. tuberculosis during infection. We have expressed and reconstituted the active enzyme from inclusion bodies in E. coli. MmcO exhibits maximal activity against the experimental substrate 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) or ABTS, at pH 4. The enzyme also exhibits ferroxidase activity at pH 4. Most notable was the finding that MmcO is able to scavenge the reactive oxygen species (ROS) generated by the xanthine/xanthine oxidase enzyme system. This ROS scavenging activity of MmcO was also evident against ROS generated by THP-1 cells. We propose that MmcO protects M. tuberculosis during infection against ROS attack in addition to providing copper resistance to the pathogen.
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PMID:The multicopper oxidase of Mycobacterium tuberculosis (MmcO) exhibits ferroxidase activity and scavenges reactive oxygen species in activated THP-1 cells. 3127 55


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