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:1.17.3.2 (xanthine oxidase)
8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In sheep from biogeochemical provinces enriched by molybdenum and copper and in a model form of molybdenum toxicosis in animals, the important role of enzymic and neurohumoral systems in the development of adaptation to excessive uptake of molybdenum and copper has been demonstrated. Adaptive reorganization of the activity of enzymic systems (xanthine oxidase, ceruloplasmin, succinate dehydrogenase, aspartate and alanine aminotransferases) and gradual involvement of neurohumoral mechanisms of the sympathoadrenal and cholinoreactive systems provide for adaptation of some animals in molybdenum and copper-molybdenum biogeochemical provinces. In other sheep, under the same conditions, dystonic disturbances in the vegetative nervous systems are observed together with the development of molybdenum toxicosis.
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PMID:[The enzymatic chemical mechanisms of adaptation]. 183 7

Inflammation increases plasma levels of ceruloplasmin, a copper protein with possible antioxidant function. This paper describes modulation of these increases by copper intake, and describes combined effects of inflammation and copper intake on Cu-Zn and extracellular (EC) superoxide dismutase (SOD) activities. Turpentine injections in rats fed 1 of 4 copper levels increased ceruloplasmin activities, but values were sensitively limited by copper intake. Cu-Zn SOD activities in the liver, but not in erythrocytes or lungs, were reduced by inflammation in each dietary copper group. Inflammation in rats fed a standard mixed feed diet reduced plasma EC superoxide dismutase activities measured by inhibition of pyrogallol autoxidation. Different results were obtained with 3 xanthine oxidase based SOD assays which were each subject to assay interference. Studies in humans found a group of rheumatoid arthritis patients to possess relatively low erythrocyte SOD and relatively high ceruloplasmin activities. Activity levels of SOD, but not of ceruloplasmin, increased after 4 weeks of copper supplementation (2 mg/day). The fate of cellular Cu-Zn SOD activity contents in inflamed tissues is largely uninvestigated. However, interleukin-1, a hormone released at inflammation sites, elevated Cu-Zn SOD activities in cultured fibroblasts.
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PMID:Effects of inflammation on copper antioxidant enzyme levels. 256 Jun 8

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 lipid peroxidation process is enhanced in both hyperoxygenated or underoxygenated tissues though its mechanism of production is different. Because in thyroid functional diseases there are severe disorders in tissue oxygenation we studied the lipid peroxidation process by using the serum level of malondialdehyde (MDA) as indicator. We also determined the serum ceruloplasmin (CP), an enzymatic protein belonging to the circulating system of antioxidative protection and also playing a role in the cell-mediated immunity. We also followed serum level of uric acid (UA). The determinations were performed on serum samples collected from three groups: 1, adult control subjects: 2. adult untreated hyperthyroid patients, and 3. adult hypothyroid thyroidectomized patients to whom replacement therapy was discontinued for at least 15 days. The mean MDA level was significantly higher in both hyperthyroid and hypothyroid patients by comparison to the control group. CP mean level was significantly lower than in controls. It was concluded that in post thyroidectomy hypothyroidism an enhancement of lipid peroxidation does exist and that its consequences are probably aggravated by the low serum CP level. The enhancement of the process occurs by other mechanisms than for hyperthyroid group. At hypothyroid patients there is an ADP excess which is degenerated to xanthine, the substrate of xanthine oxidase resulting in toxic anion superoxide and UA. In contrast with hyperthyroid group, in hypothyroid patients we observed significant higher values of UA in comparison to the controls. The excess of MDA found in hyperthyroid patients is statistically significant, but its consequences are probably less severe because the serum CP is higher than normal, a rather expected finding for an autoimmune disease.
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PMID:Significance of high levels of serum malonyl dialdehyde (MDA) and ceruloplasmin (CP) in hyper- and hypothyroidism. 338 87

The O2-utilizing (type O, oxidase) form of xanthine oxidoreductase is primarily responsible for its ferroxidase activity. This form of xanthine oxidoreductase has 1000 times the ferroxidase activity of the serum ferroxidase caeruloplasmin. It has the ability to catalyse the oxidative incorporation of iron into transferrin at very low Fe2+ and O2 concentrations. Furthermore, the pH optimum of the ferroxidase activity of the enzyme is compatible with the conditions of pH that normally exist in the intestinal mucosa, where it has been proposed that xanthine oxidoreductase may facilitate the absorption of ionic iron. Modification of the molybdenum (Mb) centres of the enzyme in vitro by treatment with cyanide, methanol or allopurinol completely abolishes its ferroxidase activity. The feeding of dietary tungsten to rats, which prevents the incorporation of molybdenum into newly synthesized intestinal xanthine oxidoreductase, results in the progressive loss of the ferroxidase activity of intestinal-mucosa homogenates. Removal of the flavin centres from the enzyme also results in the complete loss of ferroxidase activity; however, the ferroxidase activity of the flavin-free form of the enzyme can be restored with artificial electron acceptors that interact with the molybdenum or non-haem iron centres. The presence of superoxide dismutase or catalase in the assay system results in little inhibition of the ferroxidase activity of xanthine oxidoreductase.
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PMID:Studies of the ferroxidase activity of native and chemically modified xanthine oxidoreductase. 375 93

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

The nonceruloplasmin enzyme located in the intestinal mucosa which promotes the incorporation of iron into transferrin has been resolved into a small, heat-stable component and a heat-labile protein component. The small, heat-stable component was purified from the high-speed supernatant of intestinal mucosal homogenates by ion-exchange chromatography and gel filtration and identified as xanthine. The heat labile protein component was purified from the high-speed supernatant of intestinal mucosal homogenates by heat treatment, gel filtration, and ion-exchange chromatography. The physical, spectral, and kinetic properties of the heat-labile protein component strongly suggest that it is xanthine oxidase. By promotion of the oxidation and incorporation of iron into transferrin, intestinal xanthine oxidase could perform a similar function in iron absorption as ceruloplasmin serves in the mobilization of iron from liver stores.
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PMID:Purification and characterization of the intestinal promoter of iron(3+)-transferrin formation. 625 34

Superoxide (.O-2) is demonstrated to participate at the prostaglandin phase swelling (2-4 h) of carrageenan paw edema. Superoxide production is inhibited in vitro by typical anti-inflammatory drugs, but these drugs did not scavenge superoxide which was produced by xanthine oxidase. Phosphate, pyrophosphate, ATP, ADP and sulfate were essential for superoxide production by macrophages. These anions can induce paw swelling and are reported to increase in rheumatic patients. A mixture of macrophages and lymphocytes from BCG sensitized guinea-pigs was cultured for 2 days with SOD or D-mannitol. Nitroblue tetrazolium reduction (formazan formation) was inhibited by these agents, suggesting that the hydroxyl radical (.OH) is necessary for metabolic activation of macrophage. Lympholine-like factor of which production or release is enhanced by hydroxyl radical, activates macrophage. Production of oxygen radicals may increase rapidly by this chain cycle reaction. Possible relations of oxygen radicals to prostaglandin(s) biosyntheses, chemotaxis, lysosomal enzyme release protease participation, were discussed. Endogenous SOD, epinephrine, ceruloplasmin, blood plasma proteins, inflammatory fluid, may modulate the amount of superoxide by their superoxide scavenging capacities.
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PMID:Inflammation and superoxide production by macrophages. 626 69

Superoxide anion radicals have been implicated recently as mediators of inflammation and tissue injury. Protection from superoxide anion radicals is provided primarily by a copper-containing, intracellular enzyme (superoxide dismutase) (SOD) that catalyzes the dismutation of superoxide to hydrogen peroxide and oxygen. We have found that the action of cytoplasmic SOD to scavenge superoxide and thereby to inhibit superoxide-mediated reactions can be mimicked by the copper-containing plasma protein and acute-phase reactant, ceruloplasmin. Ceruloplasmin, at concentrations present in normal plasma, inhibited reduction of both cytochrome c and nitroblue tetrazolium (NBT) mediated by the aerobic action of xanthine oxidase on hypoxanthine (a superoxide-generating system). Ceruloplasmin neither inhibited formation of uric acid by xanthine oxidase nor accelerated autooxidation of cytochrome c. Furthermore, in an experimental system in which contact between ceruloplasmin and indicator was prevented by a relatively impermeable lipid membrane barrier, ceruloplasmin inhibited reduction of NBT trapped within liposomes exposed to xanthine oxidase and hypoxanthine. Ceruloplasmin also inhibited reduction of cytochrome c and NBT mediated by the aerobic action of xanthine oxidase on acetaldehyde (another superoxide-generating system) and mimicked the activity of purified human erythrocyte SOD by inhibiting photoreduction of NBT and by accelerating aerobic photooxidation of dianisidine. Ceruloplasmin could be separated from purified human erythrocyte SOD by electrophoresis on alkaline 12% polyacrylamide gels and identified by its superoxide-scavenging activity. These results suggest that ceruloplasmin may function as a circulating scavenger of oxygen-derived free radicals.
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PMID:Ceruloplasmin: an acute phase reactant that scavenges oxygen-derived free radicals. 628 6

It has been known that there is remarkable antioxidant activity in the human sera, especially those in inflammation and pregnancy. In the present investigation, various sera were examined for the antioxidant activity with the aid of cultured cells. It was recognized that the serum added to the culture medium protected cells from harmful action of active oxygen generated by a hypoxanthine-xanthine oxidase (HX-XO) system. The inflammatory serum has the greatest protective power, followed by pregnant and normal sera in this order. The antioxidant activity of the serum was inversely related to the Fe concentrations. The addition of ceruloplasmin with SOD action could not inhibit the tissue damage, while addition of catalase or hemoglobin with catalase activity could inhibit it. The protective effect was valid against not only HX-XO, but also H2O2. These results show that the chief active oxygen to cause cell damage is H2O2 and the scavenger antioxidants in the serum are hemoglobin and catalase.
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PMID:Protective effect of the serum against cellular damage by active oxygen in culture. 654 44


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