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:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study evaluates cerebral entry of mouse interferon alpha/beta (MuIFN alpha/beta) or mouse interferon gamma (MuIFN-gamma) following continuous (3 day), subcutaneous infusion of normal or glioma bearing mice. The intracerebral C57BL/6 mouse glioma-26 (G-26) model was used at days 10-14 post tumor implant, the advanced stage of glioma progression as defined by histology and the median survival time (27 +/- 3.8 days). The infusion of horseradish peroxidase (HRP) in vivo at day 10 or 11 post glioma implant showed strong staining in the tumor bed indicating compromised blood-brain barrier (BBB). In addition, histochemistry with Bandeiraea simplicifolia isolectin B4 demonstrated the accumulation and/or activation of macrophage/microglia. The 3 day infusion of mice (day 11-14 post tumor implant) via subcutaneous (sc) osmotic micro-pumps with MuIFN alpha/beta (8x10(5) - 1.7x10(6) international units [IU]/ml) or with recombinant mouse interferon gamma (rMuIFN-gamma) (1x10(6) IU/ml) resulted in a low but detectable (1-5 IU/ml) cerebral level of IFN. The IFN levels in the blood (20-40 IU/ml) and brain, measured by assay of inhibition of viral cytopathic effect (CPE) or ELISA assay for MuIFN-gamma, showed no difference between normal and glioma bearing mice. The lipoxygenase (LO) activity (dioxygenase) of glioma tissue and contralateral control was evaluated in non-treated and MuIFN alpha/beta continuously (3 day) treated mice. The LO activity in glioma tissue was significantly higher (p < 0.05) than the contralateral control in non-treated mice. However, following sc MuIFN alpha/beta infusion the LO activity of glioma decreased to control level.
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PMID:Interferon entry through the blood-brain barrier in glioma and its effect on lipoxygenase activity. 752 Nov 51

Phenytoin and related proteratogens may be bioactivated by peroxidases to a reactive free radical intermediate that initiates teratogenesis. This study evaluated the potential molecular targets mediating phenytoin teratogenicity. In vitro phenytoin-induced oxidative tissue damage following metabolic activation by prostaglandin H synthase (PHS) and lipoxygenases (LPOs) was quantified in both maternal hepatic microsomes and embryonic 9000g supernatant (S-9) from CD-1 mice, using lipid peroxidation and protein oxidation and degradation as indices. Phenytoin (0-0.2 mM) and the PHS/LPO cofactor arachidonic acid (AA, 0-1.0 mM) were incubated with maternal hepatic microsomes or embryonic S-9 (2 mg) for 0-60 min. Lipid peroxidation was measured by the formation of thiobarbituric acid-reactive substance, protein oxidation quantified by the formation of carbonyl groups in proteins, and protein degradation measured by the release of primary amines. Phenytoin was cooxidized by peroxidases in both maternal hepatic microsomes and embryonic S-9 to initiate oxidative damage to tissue lipids and proteins. The lipid peroxidation and protein oxidation and degradation were dependent on incubation time, AA concentration, and phenytoin concentration (p < 0.05), indicating that peroxidases were involved in phenytoin metabolic activation. Phenytoin-initiated oxidative tissue damage in maternal hepatic microsomes was inhibited by the cyclooxygenase inhibitor indomethacin, confirming that PHS was involved in the reactions. Phenytoin-induced oxidative damage in embryonic S-9 was not reduced by indomethacin, but was by nordihydroguaiaretic acid, an antioxidant and LPO inhibitor, indicating that additional enzymes containing peroxidase activity, such as LPO, may play a substantial role in phenytoin metabolic activation in embryonic tissues. Phenytoin-initiated lipid peroxidation and protein oxidation were early events, preceding protein degradation (10 min versus 60 min), and a lower phenytoin concentration was needed for lipid peroxidation (0.04 mM) and protein oxidation (0.01 mM) than for protein degradation (0.08 mM), suggesting that phenytoin-initiated protein and lipid oxidation may be two potential causes for protein cleavage. These results provide an in vitro basis for the in vivo evidence that embryonic lipid and protein may constitute important molecular targets mediating phenytoin teratogenicity, wherein peroxidase-catalyzed metabolic activation initiates early macromolecular oxidation by reactive oxygen species.
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PMID:Potential molecular targets mediating chemical teratogenesis: in vitro peroxidase-catalyzed phenytoin metabolism and oxidative damage to proteins and lipids in murine maternal hepatic microsomes and embryonic 9000g supernatant. 767 59

1. Present study reports the ability of partially purified peroxidase and lipoxygenase from human fetal tissues at 10 weeks of gestation to oxidize selected xenobiotics in vitro. 2. Peroxidase was found to oxidize four different chemicals in the presence of H2O2. Sodium azide and potassium cyanide inhibited peroxidase activity towards guaiacol in a concentration-dependent manner. 3. The dioxygenase and co-oxidase activities of lipoxygenase towards linoleic acid and four model xenobiotics, respectively, were observed. Both the catalytic activities of lipoxygenase were significantly inhibited by < 1.0 microM nordihydroguaiaretic acid. 4. These findings suggest that peroxidase and lipoxygenase may be important pathways for peroxidative xenobiotic oxidation in human fetal tissues.
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PMID:Peroxidative xenobiotic oxidation by partially purified peroxidase and lipoxygenase from human fetal tissues at 10 weeks of gestation. 771 49

To avoid fat deterioration in grain products during storage the cereal inherent enzymes lipase, lipoxygenase and peroxidase have to be inactivated. Known methods for the determination of the enzymes activity are tested and their applicability evaluated. Own optimized methods are presented. In laboratory and semiindustrial extrusion tests (laboratory single screw extruder, twin screw extruder, short screw extruder) the degree of enzyme inactivation of wheat bran, rye and maize bran, and oat bran is determined in dependence on the extrusion parameters. The enzymes mentioned already had been inactivated at mild extrusion conditions (temperature < 120 degrees C, moisture 20%, low mechanical stress). Only in brans of high fat content (10-14%) or high moisture (> 25%) minor residual activities of peroxidase and lipase were observed.
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PMID:[Determination of the activities of lipase, lipoxygenase and peroxidase in native and extruded cereal brans]. 783 35

The naturally occurring catechol derivative caffeic acid is a moderate stimulator of prostaglandin H synthase cyclooxygenase activity and a good reducing substrate for prostaglandin H synthase-compounds I and II. The discrepancy between the two properties is explained by a specific peroxidative mechanism that includes the formation of an inhibitory complex of caffeic acid with native enzyme followed by a three-step irreversible ping-pong peroxidation. The concentration of caffeic acid necessary to produce 50% stimulation of 0.2 mM arachidonic acid oxidation is 0.8 +/- 0.1 mM. The rate constant for the reaction of prostaglandin H synthase with hydrogen peroxide, determined from steady-state results, is (5.68 +/- 0.1) x 10(5) M-1 s-1. The rate constant for the reaction of prostaglandin H synthase-compound II with caffeic acid is (1.25 +/- 0.1) x 10(6) M-1 s-1. The dissociation constant of caffeic acid from the inhibitory complex is 35 +/- 10 microM. In diluted enzyme solutions, caffeic acid binding is diminished and the enzyme exhibits higher peroxidase activity. Our results suggest that caffeic acid is not a O-demethylation product of ferulic acid degradation catalyzed by prostaglandin H synthase, nor a chelating agent for the heme iron. The oxidation of caffeic acid could be important in the regulation of both prostaglandin H synthase and lipoxygenase activities and hence prostaglandin and leukotriene biosynthesis.
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PMID:Oxidation kinetics of caffeic acid by prostaglandin H synthase: potential role in regulation of prostaglandin biosynthesis. 784 5

Lipoxygenase (LOX) (EC 1.13.11.12) oxidized a wide range of phenothiazine (Pt) tranquillizers to their corresponding radical cations in the presence of H2O2 by means of an enzymatic chemical second-order mechanism with substrate regeneration similar to that of horseradish peroxidase. The optimum pH of LOX for this hydroperoxidase activity was in the acid range (pH 3.0-4.0), as has been shown for other Pt oxidizing systems, such as peroxidase/H2O2 and haemoglobin. LOX showed Michaelis constants for Pt ranging from 1.4 to 8.5 mM and which, in some cases, e.g. trifluoperazine, displayed substrate inhibition. By contrast, it had a high affinity for H2O2 in the microM to mM range. A new, previously undescribed plot, which relates the enzymatic affinity and the apparent second-order decay of the cation radical, was developed to study the influence of the 2- and 10-substituents in the Pt ring. The implications of this new plot and the LOX-mediated Pt oxidation are also discussed.
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PMID:Enzymatic oxidation of phenothiazines by lipoxygenase/H2O2 system. 803 16

The peroxidative metabolism of N-methylcarbazole emits light independently of the presence of oxygen. It is likely that two chemiexcited transients are formed by electron transfer to the activated peroxidase, the cation radical by one electron transfer and a cation biradical by two electron transfer consistent with the failure to observe horseradish peroxidase-II in the steady state of the reaction. In the spectral range investigated (390-700 nm) the observed emission (570-700 nm) is ascribed to the biradical, as the latter is equivalent to an excited state of the postulated iminium cation. While lipoxygenase has no effect upon N-methylcarbazole, it markedly enhances the emission if peroxidase is present. This effect requires oxygen and is ascribed to an excited product formed by lipoxygenase acting upon an intermediate hydroperoxide of the aerobic process promoted by peroxidase. Our results are of importance on two counts. First they extend to N-methylcarbazole the formation of excited species in the peroxidative metabolism of important xenobiotics. Second, the mechanistic information they provide supports the scheme of metabolism postulated by Kedderis et al. (1986, J. Biol. Chem. 261, 15910-15914).
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PMID:Chemiexcitation in the peroxidative metabolism of N-methylcarbazole: mechanistic implications. 806 26

The effect of polychlorinated biphenyls (PCB) on the state of the antioxidant system and lipid peroxidation in the liver and muscles of two Black Sea fish species-Mullus barbatus and Scorpaena porcus-has been studied. It was found that in the muscles PCB were accumulated in lesser amounts than in the liver. In the liver the activity of antioxidant enzymes did not differ significantly in the fishes kept in sea water, aquarium or aquarium plus PCB, whereas in the muscles there was an increase in the lipoxygenase activity and a decrease in the peroxidase activity. The levels of antioxidants (glutathione, carotenoids, vitamins A, E and K) and the lipid component ratio did not change considerably in control and experimental fishes. In the muscles and livers of fishes exposed to PCB there was a tendency of triene conjugate and lipid hydroperoxide content to increase. There was an increase in the correlations in the sequence: sea water-->aquarium-->aquarium plus PCB between all the parameters under study in the muscles and livers which is suggestive of mobilization of molecular protective mechanisms in response to detrimental factors.
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PMID:[Effect of polychlorinated biphenyls on the activity of antioxidant enzymes and lipid peroxidation in muscles and liver of two species of black sea fish]. 811 36

This study was designed to characterize the role of arachidonate 5-lipoxygenase metabolism during experimental intestinal ischemia-reperfusion (I/R) injury. Canines were subjected to 3 hr of intestinal ischemia followed by 1 hr of normobaric reperfusion. Intestinal ischemia followed by 1 hr of normobaric reperfusion. Intestinal mucosal leukotriene B4 and leukotriene C4 synthesis tripled after ischemia and ischemia-reperfusion, relative to non-ischemic intestinal mucosa. The flux of fluid and protein from the capillary to the lumen also increased 3-fold after I/R. The selective 5-lipoxygenase synthesis inhibitor A-64077 (Ziluten, 5 mg/kg, p.o.) abolished I/R-induced leukotriene synthesis and reduced transluminal protein flux (50%) but did not influence the lumenal accumulation of fluid after I/R. In animals treated with the leukotriene synthesis inhibitor, intestinal vascular resistance significantly declined during the imposed ischemia period and after 60 min of reperfusion. Mucosal myeloperoxidase activity, a biochemical marker for tissue neutrophils, rose significantly after I/R, and these increases were prevented with the 5-lipoxygenase synthesis inhibitor. In other experiments, the lipoxygenase inhibitor nondihydroguaretic acid produced similar results to those of A64077. In an attempt to determine the source of mucosal leukotrienes during intestinal I/R, we imposed in vitro ischemia and reperfusion on normal mucosal tissue in a blood-free environment. Mucosal tissue was incubated in Krebs buffer under oxygen for 3 hr to simulate the control condition, under nitrogen for 3 hr to simulate ischemia and under nitrogen for 2 hr followed by oxygen for 1 hr to simulate I/R.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of the arachidonate 5-lipoxygenase synthesis inhibitor A-64077 in intestinal ischemia-reperfusion injury. 816 54

A new model of local inflammation has been developed: intradermal zymosan-induced mouse ear edema. The symptoms of inflammation induced by injecting zymosan into one of the ears were followed up for 72 h. The ear edema and the local accumulation of polymorphonuclear leukocytes' (PMN) marker enzyme, myeloperoxidase (MPO), were determined. Edema peaked at 4-6 h, while MPO activity peaked at 24 h after zymosan application. The correlation between inflammatory response and concentration of zymosan was also tested. Of the various concentrations tested, 1% suspension has been found optimal. Anti-inflammatory drugs and mediator antagonists were examined in order to establish the selectivity and sensitivity of the assay. A glucocorticoid (dexamethasone), two cyclooxygenase inhibitors (indomethacin, piroxicam) and an interleukin-1 (IL-1) release inhibitor (IX 207-887, Sandoz) all reduced edema and MPO activity as well. However, a lipoxygenase inhibitor (phenidone), a serotonin receptor antagonist (methysergide) and H1 and H2 receptor antagonists (clemastine and cimetidine, respectively) all failed to inhibit the reaction.
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PMID:A new assay for antiphlogistic activity: zymosan-induced mouse ear inflammation. 830 41


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