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

Two isozymes of catalase (EC 1.11.1.6), one with typically low peroxidatic activity (CAT-1) and the other with enhanced-peroxidatic activity (EP-CAT or CAT-3) have been purified to electrophoretic homogeneity from tobacco (Nicotiana sylvestris) seedlings and antibodies prepared against each. The isozyme proteins showed no immunological cross-reactivity. The subunit Mr was 55,300 +/- 750 for CAT-1 and 53,300 +/- 850 for CAT-3 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the catalatic reaction, the apparent Km values for CAT-1 and CAT-3 were 0.057 and 0.054 M, respectively, and the kcat values were 4.8 x 10(7) and 3.0 x 10(6) min-1, respectively. In the peroxidatic reaction, both have similar apparent Km's for H2O2. The apparent Km values for CAT-3 for the series methyl, ethyl, propyl, butyl, and allyl alcohols were 2.48, 5.6, 38.6, 429, and 16.3 mM, respectively. For CAT-1, the values were 697, 55.8, no detectable reaction with propyl and butyl, and 163 mM, respectively. Neither isozyme utilized dianisidine or guaiacol in the peroxidatic reaction. Catalase activity (CAT-2) which eluted in an intermediate position between CAT-1 and CAT-3 from a chromatofocusing column was composed of only one subunit whose Mr coincided with CAT-1, and only the antibody to CAT-1 reacted with CAT-2 protein. Thus, CAT-2 and CAT-1 appear closely related while CAT-3 is distinctly different.
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PMID:Purification and characterization of an isozyme of catalase with enhanced-peroxidatic activity from leaves of Nicotiana sylvestris. 227 60

Vanadium compounds are known to stimulate the oxidation of NAD(P)H, but the mechanism remains unclear. This reaction was studied spectrophotometrically and by electron spin resonance spectroscopy (ESR) using vanadium in the reduced state (+4, vanadyl) and the oxidized state (+5, vanadate). In 25 mM sodium phosphate buffer at pH 7.4, vanadyl was slightly more effective in stimulating NADH oxidation than was vanadate. Addition of a superoxide generating system, xanthine/xanthine oxidase, resulted in a marked increase in NADH oxidation by vanadyl, and to a lesser extent, by vanadate. Decreasing the pH with superoxide present increased NADH oxidation for both vanadate and vanadyl. Addition of hydrogen peroxide to the reaction mixture did not change the NADH oxidation by vanadate, regardless of concentration or pH. With vanadyl however, addition of hydrogen peroxide greatly enhanced NADH oxidation which further increased with lower pH. Use of the spin trap DMPO in reaction mixtures containing vanadyl and hydrogen peroxide or a superoxide generating system resulted in the detection by ESR of hydroxyl. In each case, the hydroxyl radical signal intensity increased with vanadium concentration. Catalase was able to inhibit the formation of the DMPO--OH adduct formed by vanadate plus superoxide. These results show that the ability of vanadium to act in a Fenton-type reaction is an important process in the vanadium-stimulated oxidation of NADH.
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PMID:Importance of hydroxyl radical in the vanadium-stimulated oxidation of NADH. 253 40

In previous papers, we have reported that methylguanidine (MG), a known uremic toxin, was synthesized from creatinine (Cr) by active oxygen generated not only by chemical reagents but also by isolated rat hepatocytes. In this paper, we studied whether or not active oxygen generated by stimulated human neutrophils produces MG from Cr. MG was measured after incubating 2 x 10(6) human neutrophils for 2 h in 1 ml of Hanks' balanced salt solution (pH 7.4) containing 100 mg/dl Cr at 37 degrees C after the addition of phorbol myristate acetate (PMA). MG was measured by high pressure liquid chromatography followed by reaction with 9, 10-phenanthrenequinone. MG was synthesized by the stimulated neutrophils and not by the unstimulated ones. MG synthesis reached a plateau (1.11 +/- 0.03 nmol/120 min/2 x 10(6) cells) at a concentration of 0.125 microM PMA and reached a maximum value (1.95 +/- 0.03 nmol/120 min/2 x 10(6) cells) at a concentration of 100 mg/dl Cr. MG synthesis increased depending on the concentration of neutrophils between 1 and 8 x 10(6)/ml and increased depending on the duration of incubation up to 4 h. MG synthesis was strongly inhibited by superoxide dismutase, by the scavengers of hypochloride (taurine and methionine) and by sodium azide. Catalase and the scavenger of the hydroxyl radical (dimethyl sulfoxide) inhibited MG synthesis less effectively. The effects of the scavengers of active oxygen suggest the participation of active oxygen in MG synthesis from Cr in this system. Among the active oxygen species, superoxide anion and hypochloride play an important role in this system.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Methylguanidine synthesis by active oxygen generated by stimulated human neutrophils]. 259 20

Normal human neutrophils triggered by precipitating immune complexes (IC), soluble IC (sIC) or heat-aggregated IgG (HAIgG) displayed low levels of cytotoxicity towards nonsensitized target cells. Catalase, but not heated catalase, completely impaired this nonspecific cytotoxicity (NSC), suggesting a key role for hydrogen peroxide (H2O2) in the lysis of target cells. Superoxide dismutase (SOD) and certain HO. and 1O2 scavengers were unable to exert significant effects. Three haem-enzyme inhibitors, sodium azide, sodium cyanide and 3-amino-1,2,4-triazole did not decrease neutrophil NSC, but markedly enhanced it. This data suggest that the mechanism involved was not dependent upon myeloperoxidase (MPO). The analysis of neutrophil-mediated ADCC indicates that oxygen-dependent but MPO-independent mechanisms appeared to be operative in this system. It was also found that the microfilament disrupting agents, cytochalasin B (CB) and dihydrocytochalasin B (dhCB), as well as the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), significantly enhanced NSC. In contrast, these compounds partially inhibited ADCC. This cytotoxic system provides a suitable model to study events that may occur during the course of immune complex diseases and also permits the evaluation of alternative lytic mechanisms triggered through neutrophil Fc gamma receptors.
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PMID:Neutrophil-mediated cytotoxicity triggered by immune complexes: the role of reactive oxygen metabolites. 282 3

Photoradiation therapy with porphyrins and light offers an alternative approach to the management of certain types of cancer. The mechanism of tissue destruction mediated by this modality is poorly understood. In this study, epidermal microsomes incubated in vitro with Photofrin-I (Pf-I) and Photofrin-II (Pf-II) followed by exposure to radiation (approximately 400 nm) resulted in increased (180%) NADPH-supported (enzymatic) as well as ADP/iron-supported (140%) (nonenzymatic) lipid peroxidative damage as measured by malondialdehyde formation. Lipid peroxidation by Pf-I and Pf-II was found to be differentially affected by quenchers of singlet oxygen (2,5-dimethylfuran, histidine, beta-carotene, ascorbic acid, and sodium azide), superoxide anion (superoxide dismutase), and the hydroxyl radical (sodium benzoate, mannitol, and ethanol). Catalase, a quencher of hydrogen peroxide, afforded significant protection only against Pf-II-enhanced lipid peroxidative damage while it had little effect against the Pf-I-mediated reaction. Deuterium oxide, which is known to increase the half-life of singlet oxygen, was found to enhance Pf-I-mediated lipid peroxidation but produced insignificant effects upon Pf-II-mediated photosensitization. Our results indicate that Pf-I and Pf-II, which are employed for the photodynamic therapy of malignant tumors, evoke membrane damage by generating different reactive oxygen species. The Pf-I-mediated photodestruction mainly involves a type II mechanism via singlet oxygen formation, whereas Pf-II-mediated photodestruction preferentially involves a type I mechanism by generating superoxide anions and hydroxyl radicals. Our data indicate that tumor necrosis evoked by porphyrins and light is likely due to the generation of reactive oxygen species.
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PMID:Differential role of reactive oxygen intermediates in photofrin-I- and photofrin-II-mediated photoenhancement of lipid peroxidation in epidermal microsomal membranes. 283 56

The effect in vitro of the naturally occurring flavonoid silybin on human polymorphonuclear leukocyte (PMN) functions has been studied. Preincubation of PMNs for 10 min at 37 degrees C with silybin inhibited, in a dose-dependent way, the luminol-enhanced chemiluminescence (CL) generated by stimulated cells without affecting the non-enhanced CL or superoxide anion production evaluated by the cytochrome C reduction assay. No significant effect of silybin on PMN phagocytic or chemotactic activities were found. Silybin did not absorb light at the wavelength of luminol-enhanced CL and was not toxic to PMNs at the concentrations used. Catalase, a scavenger of H2O2, inhibited luminol-enhanced CL to a similar degree as silybin; moreover, when incubated together with PMNs, silybin and catalase did not produce an additive inhibition of CL. On the contrary, the simultaneous addition of silybin and sodium azide, an inhibitor of myeloperoxidase, further increased inhibition over that seen with azide alone. These results suggest that inhibition of H2O2 may be the mechanism by which silybin inhibits the luminol-enhanced CL generated by stimulated PMNs. Such results indicate a possible anti-inflammatory activity for silybin even if their clinical relevance remains to be elucidated.
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PMID:Modulation of human polymorphonuclear leukocyte function by the flavonoid silybin. 285 72

Reactivities of benzene metabolites (phenol, catechol, hydroquinone, 1,4-benzoquinone, 1,2,4-benzenetriol) and related polyphenols (resorcinol, pyrogallol, phloroglucinol) with DNA were investigated by a DNA sequencing technique using 32P 5'-end-labeled DNA fragments obtained from human c-Ha-ras-1 protooncogene, and the reaction mechanism was studied by UV-visible and electron-spin resonance spectroscopies. 1,2,4-Benzenetriol caused strong DNA damage even without alkali treatment. Alkali-labile sites induced by 1,2,4-benzenetriol were base residues of guanine and adjacent thymine. Catalase, superoxide dismutase and methional inhibited the DNA damage completely, but sodium formate did not inhibit it. 1,2,4-Benzenetriol-induced DNA damage was inhibited by the addition of a Cu(I)-specific chelating agent, bathocuproine, and was accelerated by the addition of Cu(II). The addition of Fe(III) did not create any significant effects on 1,2,4-benzenetriol-induced DNA damage. Electron-spin resonance studies using spin traps demonstrated that addition of Fe(III) increased hydroxyl radical production during the autoxidation of 1,2,4-benzenetriol, whereas the addition of Cu(II) did not. The results suggest that DNA damage was caused by an unidentified active species which was produced by the autoxidation of 1,2,4-benzenetriol in the presence of Cu(II), rather than by hydroxyl radicals. The possibility that 1,2,4-benzenetriol-induced DNA damage is one of the primary reactions in carcinogenesis induced by benzene is discussed.
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PMID:Human DNA damage induced by 1,2,4-benzenetriol, a benzene metabolite. 290 43

Catalase (hydroperoxidase II or HPII) of Escherichia coli K12 has been purified using a protocol that also allows the purification of the second catalase HPI in large amounts. The purified HPII was found to have equal amounts of two subunits with molecular weights of 90,000 and 92,000. Only a single 92,000 subunit was present in the immunoprecipitate created when HPII antiserum was added directly to a crude extract, suggesting that proteolysis was responsible for the smaller subunit. The apparent native molecular weight was determined to be 532,000, suggesting a hexamer structure for the enzyme, an unusual structure for a catalase. HPII was very stable, remaining maximally active over the pH range 4-11 and retaining activity even in a solution of 0.1% sodium dodecyl sulfate and 7 M urea. The heme cofactor associated with HPII was also unusual for a catalase, in resembling heme d (a2) both spectrally and in terms of solubility. On the basis of heme-associated iron, six heme groups were associated with each molecule of enzyme or one per subunit.
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PMID:Purification and characterization of catalase HPII from Escherichia coli K12. 301 70

The metabolic disorder, alkaptonuria, is distinguished by elevated serum levels of 2,5-dihydroxyphenylacetic acid (homogentisic acid), pigmentation of cartilage and connective tissue and, ultimately, the development of inflammatory arthritis. Oxygen radical generation during homogentisic acid autoxidation was characterized in vitro to assess the likelihood that oxygen radicals act as molecular agents of alkaptonuric arthritis in vivo. For homogentisic acid autoxidized at physiological pH and above, yielding superoxide (O2-)2 and hydrogen peroxide (H2O2), the homogentisic acid autoxidation rate was oxygen dependent, proportional to homogentisic acid concentration, temperature dependent and pH dependent. Formation of the oxidized product, benzoquinoneacetic acid was inhibited by the reducing agents, NADH, reduced glutathione, and ascorbic acid and accelerated by SOD and manganese-pyrophosphate. Manganese stimulated autoxidation was suppressed by diethylenetriaminepentaacetic acid (DTPA). Homogentisic acid autoxidation stimulated a rapid cooxidation of ascorbic acid at pH 7.45. Hydrogen peroxide was among the products of cooxidation. The combination of homogentisic acid and Fe3+-EDTA stimulated hydroxyl radical (OH.) formation estimated by salicylate hydroxylation. Ferric iron was required for the reaction and Fe3+-EDTA was a better catalyst than either free Fe3+ or Fe3+-DTPA. SOD accelerated OH. production by homogentisic acid as did H2O2, and catalase reversed much of the stimulation by SOD. Catalase alone, and the hydroxyl radical scavengers, thiourea and sodium formate, suppressed salicylate hydroxylation. Homogentisic acid and Fe3+-EDTA also stimulated the degradation of hyaluronic acid, the chief viscous element of synovial fluid. Hyaluronic acid depolymerization was time dependent and proportional to the homogentisic acid concentration up to 100 microM. The level of degradation observed was comparable to that obtained with ascorbic acid at equivalent concentrations. The hydroxyl radical was an active intermediate in depolymerization. Thus, catalase and the hydroxyl radical scavengers, thiourea and dimethyl sulfoxide, almost completely suppressed the depolymerization reaction. The ability of homogentisic acid to generate O2-, H2O2 and OH. through autoxidation and the degradation of hyaluronic acid by homogentisic acid-mediated by OH. production suggests that oxygen radicals play a significant role in the etiology of alkaptonuric arthritis.
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PMID:Homogentisic acid autoxidation and oxygen radical generation: implications for the etiology of alkaptonuric arthritis. 312 48

Campylobacters isolated in Scotland and the north of England from bovine (497 isolates) and ovine (51 isolates) faeces were studied in order to determine which simple methods would be useful for identification of groups and species. By means of the catalase test, growth and microscopic characteristics, coccal transformation and nalidixic acid (Nal) and cephalothin sensitivity, isolates were separated into 3 groups: C. jejuni - C. coli, C. hyointestinalis - C. fetus and C. fecalis - C. sputorum subsp. bubulus. Hippurate hydrolisis was used to differentiate C. jejuni (positive) from all the other Campylobacter spp (negative). The production of hydrogen sulphide in Triple Sugar Iron was used to separate C. hyointestinalis and the C. fecalis - C. sputorum subsp. bubulus group (positive) from C. fetus (negative). The production of hydrogen sulphide in iron-bisulphite-pyruvate (FBP) medium was used to separate the C. fecalis - C. sputorum subsp. bubulus group (positive) from most C. hyointestinalis isolates (96.4% were negative). Additional characteristics useful for identification of the C. fecalis - C. sputorum subsp. bubulus group were: adherent sticky growth; inhibition of growth by FBP or ferrous sulphate and sodium metabisulphite; and inversion of Nal resistance on FBP agar. Catalase test was used to separate C. fecalis (positive) from C. sputorum subsp. bubulus (negative), although these two species should be regarded as a single species with a variable catalase test. Bovine C. hyointestinalis isolates were serologically classified as type 1 (related to the porcine C. hyointestinalis standard strain NCTC 11562) and type 2 (unrelated). Based on the above criteria, isolates in cattle were classified as: 229 C. jejuni, 66 C. coli, 112 C. hyointestinalis type 1, 53 C. hyointestinalis type 2 and 37 C. fetus. In sheep they were: 25 C. jejuni, 11 C. coli, 12 C. fecalis and 3 C. sputorum subsp. bubulus.
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PMID:Identification of campylobacters from bovine and ovine faeces. 317 20


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