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

Catalase (H2O2:H2O2 oxidoreductase, EC 1.11.1.6) is of historical interest for having been the subject of some of the earliest investigations of enzymes. A feature of catalase that has been poorly understood for several decades, however, is the mechanism by which catalase remains active in the presence of its own substrate, hydrogen peroxide. We reported recently that catalase contains tightly bound NADPH. The present study with bovine and human catalase revealed that NADPH both prevents and reverses the accumulation of compound II, an inactive form of catalase that is generated slowly when catalase is exposed to hydrogen peroxide. Since the effect of NADPH occurs even at NADPH concentrations below 0.1 microM, the protective mechanism is likely to operate in vivo. This discovery of the role of catalase-bound NADPH brings a unity to the concept of two different mechanisms for disposing of hydrogen peroxide (catalase and the glutathione reductase/peroxidase pathway) by revealing that both mechanisms are dependent on NADPH.
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PMID:The function of catalase-bound NADPH. 380 1

The ability to grow a clone of the cell line, MLA144, which is a constitutive producer of interleukin 2 (IL-2), in serum-free medium permitted the study of the direct effect of various agents on cell growth and IL-2 production in a homogeneous population. Bovine serum albumin (BSA) at 4 mg/ml was optimal for cell growth and IL-2 production. Selenium at 10 ng/ml enhanced IL-2 production nearly twofold and lithium at 42 ng/ml also enhanced IL-2 production by nearly twofold. Neither compound at these levels altered cellular proliferation. Two other compounds, iron and zinc, known to be associated with cellular proliferation and/or immunoregulation did not alter IL-2 production. Catalase or horseradish peroxidase was able to substitute for BSA and maintain the long-term growth of the MLA144 clone with only a 30% decrease in the rate of cellular proliferation and a 50% decrease in IL-2 production compared to cells maintained in the serum-free formulation with BSA. Addition of 0.5 mg of BSA to the catalase serum-free formulation increased the production of IL-2 to 70% of that of cells cultured in the BSA-containing serum-free formulation. The catalase-containing serum-free formulation has the advantage of consisting of only three proteins, catalase, insulin, and transferrin, at a very low protein content. The catalase-containing serum-free medium also supported the long-term growth of a human T-cell line, HSB-2.
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PMID:Modulation of interleukin 2 release from a primate lymphoid cell line in serum-free and serum-containing media. 393 31

A rapid method that employs monolayers of different phagocytic cells, primarily from guinea pigs and mice, has allowed a kinetic determination of (a) ingestion by these cells of labeled particles, (b) fixation of (131)I and (c) microbicidal activity in the cells after periods as short as 5' of exposure of bacteria to phagocytes. Phagocytes so examined included polymorphonuclear leukocytes (PMN) elicited into the peritoneal cavity, elicited peritoneal mononuclear cells (monocytes) (MN), and peritoneal macrophages (MAC) obtained simply by lavage. Circulating PMN from normal human subjects and from children afflicted with chronic granulomatous disease were also studied. The potential for generation of H(2)O(2) (a key component of the iodinating system) of all the normal cells studied, gauged by their content of cyanide-insensitive NADH oxidase, seemed comparable. Peroxidase levels varied widely, and were highest in PMN and almost undetectable in MAC. Catalase was at negligible levels in all the cell types obtained from mice. The fixation of (131)I by phagocytes ingesting (14)C-labeled dead tubercle bacilli appeared to be primarily a function of the cellular peroxidase content. Thus, mouse macrophages, with virtually no peroxidase, displayed no fixation of iodide. PMN proved far more able to fix (131)I during phagocytosis than did MN. In experiments comparing PMN from normal human subjects and from children with chronic granulomatous disease (CGD), a sex-linked condition characterized by a deficiency of H(2)O(2) production during phagocytosis and low microbicidal activity, the iodination ratio of CGD cells was dramatically less than that of normal PMN (by about two orders of magnitude). Capacity for iodination was correlated with bactericidal activity toward E. coli. At low bacterial loads (ca. 5:1), phagocytes killed efficiently, and little discrepancy in ability among cell types was apparent. Under the stress of higher loads of (14)C-labeled E. coli (ca. 100:1), differences in bactericidal activity were exaggerated, and a substantial disparity between MN and PMN was observed in favor of the latter. The hierarchy for killing efficiencies therefore agreed with that for iodination, with one notable exception: mouse MAC were consistently competent in their killing activity, more so than MN, even though they virtually lack peroxidase and the ability to iodinate ingested bacteria.
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PMID:Iodinating ability of various leukocytes and their bactericidal activity. 414 57

1. Oxygen was taken up rapidly when pyruvate was added to mixtures of pyridoxamine and Mn(2+) ions after lag periods that were shortened by peroxidase (donor-hydrogen peroxide oxidoreductase, EC 1.11.1.7). 2. The total oxygen uptake was proportional to the pyridoxamine added and was accompanied by the disappearance of pyridoxamine; the pyruvate acted catalytically and hydrogen peroxide was not formed. 3. At pH6 more than half the pyridoxamine that disappeared was accounted for as pyridoxal and ammonia; it is suggested that the primary reaction is the oxidative deamination of the pyridoxamine. 4. Results were similar when alpha-oxobutyrate or glyoxylate were substituted for pyruvate, except that the reactions were slower and the yield of pyridoxal less. 5. The oxidative decarboxylations of alpha-oxoglutarate and phenylpyruvate are catalysed by Mn(2+) ions and these reactions are activated by peroxidase; pyridoxamine increased both the rates and total oxygen uptakes in these reactions, and ammonia was produced. 6. The lag periods in the oxidation of mixtures of pyridoxamine and alpha-oxo acids, catalysed by Mn(2+) ions, were also shortened by traces of colloidal manganese dioxide. 7. It is suggested that the activating effect of peroxidase depends on its catalysis of manganese oxidation.
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PMID:The oxidation of Schiff bases of pyridoxamine with -oxo acids by manganous ions and peroxidase. 463 37

Phenylalanine hydroxylase was prepared from rat liver and purified 200-fold to about 90% purity. All the enzymic activity of the liver appeared in a single protein of mol.wt. approx. 110000, but omission of dithiothreitol and of a preliminary filtration step to remove lipids resulted in partial conversion into a second enzymically active protein of mol.wt. approx. 250000. The K(m) and V(max.) values of the enzyme for phenylalanine, p-fluorophenylalanine and dimethyltetrahydropterin were measured; p-chlorophenylalanine inhibited the enzyme by competing with phenylalanine. Disc gel electrophoresis at pH7.2 showed a single protein band containing all the enzymic activity, but at pH8.7 the enzyme dissociated into two inactive fragments of similar but not identical molecular weight. The molecule of phenylalanine hydroxylase contained two atoms of iron, one atom of copper and one molecule of FAD; molybdenum was absent. Treatment with chelating agents showed that both non-haem iron and copper were necessary for enzymic activity. The molecule contained five thiol groups, and thiol-binding reagents inhibited the enzyme. Catalase or peroxidase enhanced enzymic activity fivefold; it is postulated that catalase (or other peroxidase) plays a part in the hydroxylation reaction independent of the protection by catalase of enzyme and cofactor from inactivation by a hydroperoxide.
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PMID:The isolation and properties of phenylalanine hydroxylase from rat liver. 485 20

1. Homogenates of guinea-pig polymorphonuclear leucocytes were separated by differential centrifugation into six particulate fractions and a soluble fraction. 2. The distributions in these fractions of protein, DNA, succinate dehydrogenase, beta-glucuronidase, peroxidase, alkaline phosphatase, acid phosphatase (against p-nitrophenyl phosphate and beta-glycerophosphate), cathepsin, and catalase were compared. 3. Almost all of the DNA sedimented in the first two pellets, indicating that the nuclei were relatively intact. 4. The four hydrolases and peroxidase showed different distribution patterns, although these activities were previously reported to be localized mainly in the single ;granule' fraction isolated from leucocytes. 5. The particles containing peroxidase, acid phosphatase and alkaline phosphatase all exhibited latency. Maximum activity for each enzyme was obtained at roughly similar concentrations of Triton X-100. 6. The acid phosphatase of these cells was distributed between two populations of particles that differed in both sedimentation characteristics and density. The acid phosphatase(s) of the two populations showed slightly different substrate specificities. This bimodal distribution was not an artifact of the procedure used to elicit the cells. 7. Catalase was recovered almost entirely in the soluble fraction and showed no latency in freshly prepared homogenates. No urate oxidase was detected. 8. We conclude that the ;granule' fraction of the polymorphonuclear leucocyte, as isolated by previous workers, contains at least three, probably more, populations of particles with different enzyme contents, and that these cells probably do not contain peroxisomes.
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PMID:The distributions of some granule-associated enzymes in guinea-pig polymorphonuclear leucocytes. 541 96

Mice were injected intravenously with beef liver catalase (mol wt 240,000) and very small doses of horseradish peroxidase (mol wt 40,000) and the site of localization of these enzymes in the kidney was studied by ultrastructural cytochemistry. 1 min after injection, catalase was present in glomerular capillary lumina and there was minimal permeation of the basement membrane. After 5-180 min, staining of the basement membrane increased progressively but was usually less than that in capillary lumina. At all time intervals the inner (sub-endothelial) layer of the basement membrane contained more reaction product than the lamina densa and the outer (subepithelial) layer. Catalase permeated the entire thickness of the basement membrane and extended up to the slit pore but not beyond the level of the slit diaphragm and was not seen in the urinary space or tubular lumina. Horseradish peroxidase permeated the whole thickness of the basement membrane within 2 min after injection; however, gradients of staining from the inner to outer layers of the basement membrane were frequently seen. The findings with both enzymes indicate that (a) the basement membrane restricts the passage of proteins over a wide range of molecular size with increasing impediment for larger molecules and (b) the slit pore functions as an additional barrier for molecules that cross the basement membrane.
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PMID:An ultrastructural study of glomerular permeability using catalase and peroxidase as tracer proteins. 551 68

1. Oxygen was taken up rapidly when pyridoxal or pyridoxal phosphate was added to mixtures of pea-seedling extracts and Mn(2+) ions. 2. The increases in total oxygen uptake were proportional to the pyridoxal or pyridoxal phosphate added and were accompanied by the disappearance of these compounds. 3. In addition to Mn(2+) ions, the reactions depended on two factors in the extracts, a thermolabile one in the non-diffusible material and a thermostable one in the diffusate; these factors could be replaced in the reactions by horse-radish peroxidase (donor-hydrogen peroxide oxidoreductase, EC 1.11.1.7) and amino acids respectively. 4. When pyridoxal phosphate was added to mixtures of amino acids and Mn(2+) ions oxygen uptake was rapid after a lag period of 30-90min.; the lag period was shortened to a few minutes by peroxidase, particularly in the presence of traces of p-cresol, or by light. 5. When pyridoxal replaced pyridoxal phosphate relatively high concentrations were required and peroxidase had only a small activating effect. 6. Pyridoxal or pyridoxal phosphate disappeared during the reactions and carbon dioxide and ammonia were formed. 7. With phenylalanine as the amino acid present, benzaldehyde was identified as a reaction product. 8. It is suggested that the reactions are oxidations of the Schiff bases formed between pyridoxal or pyridoxal phosphate and amino acids, mediated by a manganese oxidation-reduction cycle, and resulting in oxidative decarboxylation and deamination of the amino acids.
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PMID:The oxidation of Schiff bases of pyridoxal and pyridoxal phosphate with amino acids by manganous ions and peroxidase. 594 50

Current evidence suggests that bleomycin toxicity may be attributable to its DNA degradative activity possibly via generation of free radicals and O2 metabolites as mediators. Since lipopolysaccharide (LPS) has been known to provide protection against O2 toxicity, which is correlated with increased activity of O2 metabolite-detoxifying enzymes, the effect of this agent on bleomycin-induced pulmonary fibrosis was examined. Endotracheal bleomycin administration caused increased lung collagen synthesis. A single intraperitoneal injection of LPS (500 micrograms/kg) at day zero significantly decreased these increases. Total bleomycin-induced lung collagen increase was also significantly reduced. LPS alone had no significant effect on total lung catalase activity. Glutathiione peroxidase activity, however, was significantly decreased by 15.8% compared to untreated animals at 2 days after LPS treatment and remained unchanged at other time points. In addition, superoxide dismutase activity was significantly elevated by 30% above untreated animals only at 14 days after LPS administration and remained unchanged at other time points. Endotracheal bleomycin administration alone caused significant reductions in catalase activity at 2 days and 2 weeks after treatment, whereas glutathione peroxidase activity increased above control untreated animals at 2 and 4 weeks, respectively. Superoxide dismutase activity was unaffected by bleomycin treatment. Pretreatment with LPS before bleomycin prevented these reductions or caused increases in the activities of these enzymes at 2 days. Glutathione peroxidase was increased and was significantly greater than those animals treated with bleomycin alone. Catalase also was higher in the LPS plus bleomycin group (by 22.2%, p less than 0.05) than the bleomycin group alone. Compared to the effects on lung collagen synthesis and content, LPS treatment resulted in much less dramatic changes in total lung antioxidant enzyme activities. This discrepancy between the intensity of LPS effects on lung O2 metabolite-detoxifying enzymes and that on pulmonary fibrosis implies that the LPS-ameliorating effect on pulmonary fibrosis could not be totally explained by increased ability to detoxify O2 metabolites. Rather, the data would favor the possibility that LPS inhibits bleomycin-induced pulmonary fibrosis either by its known immunosuppressive effects or some other unknown mechanism. The former would be in agreement with previous data which suggest that an intact immune response is necessary for complete expression of the fibrogenic response to bleomycin.
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PMID:Inhibition of bleomycin-induced pulmonary fibrosis by lipopolysaccharide. 620 76

Changes in the activities of the enzymes catalase and peroxidase were studied in the excised leaves of ragi (Eleusine coracana Gaertn. cv PR 202) plants belonging to different ages. Catalase exhibited a positive and peroxidase a negative correlation with the changes in chlorophyll. Catalase and peroxidase were negatively correlated with each other. Peroxidase exhibited an age-related drift in its activity. Kinetin could maintain the levels of chlorophyll and catalase, and also caused an increase in peroxidase activity. Both indoleacetic acid and gibberellic acid had no effect on the changes of chlorophyll but increased peroxidase activity. Catalase levels were maintained by indoleacetic acid but gibberellic acid had no effect on this enzyme.
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PMID:Age-related changes in catalase and peroxidase activities in the excised leaves of Eleusine coracana Gaertin. cv PR 202 during senescence. 632 Dec 15


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