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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aims of this study were to investigate the interaction between oxygen radicals and mucus secretion from cultured rat gastric mucous cells, and to assess the role of prostaglandin production in the modulation of mucus secretion in vitro. Xanthine oxidase in the presence of hypoxanthine caused a dose-dependent increase in the presence of hypoxanthine caused a dose-dependent increase of mucus secretion, as assessed by release of [3H]glucosamine from prelabeled cells, whereas xanthine oxidase or hypoxanthine alone did not. Xanthine oxidase (10 mU/ml) increased release of [3H]glucosamine by 57 +/- 6% compared with control values (P less than 0.001). Catalase (3,000 U/ml) inhibited xanthine oxidase-induced mucus secretion by 69 +/- 9% (P less than 0.01), whereas superoxide dismutase did not. Pretreatment with deferoxamine, an inhibitor of hydroxyl radical generation through chelating ferric ion, diminished oxygen radical-induced mucus release to control values. Xanthine oxidase dose dependently stimulated prostaglandin E2 (PGE2) production, which was blocked by catalase but not by superoxide dismutase. However, oxygen radical stimulation of mucus secretion was not inhibited by the addition of indomethacin. Moreover, PGE2, exogenously administered, did not significantly accelerate mucus secretion. Stimulation of mucus secretion by oxygen radicals was not accompanied by increased 51Cr release or by leakage of intracellular lactate dehydrogenase. These results suggest that oxygen species, particularly hydroxyl radical, stimulate mucous glycoprotein secretion from cultured rat gastric mucous cells. However, it seems unlikely that prostaglandin production mediates the oxygen species-induced stimulation of mucus secretion.
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PMID:Oxygen metabolites stimulate mucous glycoprotein secretion from cultured rat gastric mucous cells. 192 52

Catalase from Aspergillus niger was purified to homogeneity as judged from the results of ultracentrifugation and polyacrylamide gel electrophoresis. The enzyme had a molecular weight of 385,000 as estimated from sedimentation measurements. Carbohydrate analyses showed that the catalase was a glycoprotein containing about 8.3% neutral sugar and 1.9% glucosamine. Under denaturing conditions, polyacrylamide gel electrophoresis revealed only one band with a molecular weight of 97,000 daltons in gels stained for either protein or sugar, suggesting that the native enzyme consists of four subunits with covalently bound carbohydrate. In the reaction with inhibitors, A. niger catalase showed lower affinity than the "standard" catalases. The pK values for HCN, HN3, and HF were estimated to be 3.4 (at pH 7.4), 2.3, and 1.5 (at pH 4.2), respectively. In addition, the fungal enzyme reacts with methyl hydrogen peroxide in a very unusual way. Even after the addition of a large excess of the peroxide, only catalase compound I was formed, and compound II did not appear. Using this unique property of A. niger catalase, we obtained CD and MCD spectra of compound I uncontaminated by compound II. The magnitude of the positive CD peak of compound I in the Soret region was about half that of the native enzyme. The MCD spectrum obtained was better resolved than that of bovine liver catalase compound I in the visible region.
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PMID:Properties of Aspergillus niger catalase. 715 10