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)

N-formylmethionyl (F-Met) peptides, when added alone to macrophages or polymorphonuclear leukocytes (PMN), were found to induce a chemiluminescent response of shorter duration than that produced by the commonly employed particulate stimulant, zymosan. The cellular nature of F-Met peptide-induced chemiluminescence was indicated by its dependence on cell concentration, and by its inhibition by cell disruption, heat inactivation, or previous maximal stimulation by the peptides. Comparison of PMN and macrophages from different species showed that the maximal chemiluminescent response seen in the dose-response curve of F-Met- Phe was different in different cell types. Chemiluminescence reached highest values in human PMN, it was intermediate in guinea pig macrophages and PMN, and in rabbit PMN; but it was nonexistent in rabbit alveolar macrophages and very low in rabbit peritoneal macrophages. A definite relationship was observed between peptide structure and chemiluminescent activity. Met-Phe, F- Met and Phe were inactive even at millimolar concentrations, while F-Met-Phe caused chemiluminescence at micromolar concentrations. Four active peptides were tested in guinea pig, rabbit, and human PMN, and in guinea pig alveolar and peritoneal macrophages. The relative activity of these peptides was the same in all cells studied, e.g. F-Met-Leu-Phe >> F-Met-Phe > F-Met-Val > F- Met-Ala. The values of ED50 for each peptide were also comparable to previously reported ED50 values of these peptides in inducing lysosomal enzyme release. These results were seen both in the presence and absence ofthe chemiluminescent oxidant indicator, luminol. Low concentrations of superoxide dismutase (10 mug/ml) completely inhibited chemiluminescence caused by the F-Met peptides, suggesting the involvement of 0(2)(-) or O(2)(-)-derived compounds in this response. Sodium azide, an inhibitor of peroxidase reactions, had either no effect or a slight inhibitory effect on chemiluminescence. However, when the extracellular release of lysosomal enzymes was induced by cytochalasin B, an azide- inhibitable enhancement of chemiluminescence was seen in PMN, but not in macrophages. This effect appears to be correlated with the presence of granule-associated myeloperoxidase. Although azide-inhibitable peroxidases could be a potential source of light, they did not appear to be a significant contributor in these experiments. Based on these results and on those of previous investigators, we postulate that the F-Met-peptides stimulate 0(2)(-) production in addition to stimulating lysosomal enzyme release and chemotaxis. The similar structure- activity relationship which appears to exist for these processes may indicate that they are all initiated by a single receptor mechanism. Since F-Met peptides are formed in bacteria it is likely that their actions represent an important physiologic response.
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PMID:Chemiluminescence of phagocytic cells caused by N-formylmethionyl peptides. 62 35

Aluminum intoxication is currently thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations seen during long-term hemodialysis and aging. The hypothesis that aluminum toxicity is mediated via an increased free radical production was tested by studying the effects of two aluminum and five other metallic compounds on the production of luminol-enhanced chemiluminescence (LECL) by human neutrophils. AlCl3, Al2(SO4)3 and FeCl3 were found to stimulate LECL production by human neutrophils whereas FeCl2, CuCl, CuCl2, AuCl3 were inactive. Metal chelators such as Desferal, EDTA and DETAPA suppressed aluminum-induced stimulation and depressed cell-dependent LECL below basal levels. Sodium azide and Cytochalasin B greatly depressed both basal and aluminum-induced stimulation of LECL production, suggesting that, in this system, most of this stimulation was due to myeloperoxidase. These results suggest that high tissue aluminum concentrations may induce cell-tissue lesions by stimulating local production or release of mediators of tissue damage.
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PMID:Aluminum salts stimulate luminol-enhanced chemiluminescence production by human neutrophils. 190 35

Sodium nitrite was shown to enhance the metabolism of trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BP-7,8-diol) to 7/8,9,10- and 7,10/8,9-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (tetraols) in phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocytes (PMNs). The production of these tetraols implicates the intermediate formation of the corresponding trans-7,8-dihydroxy-9,10-epoxy-7,8-9,10-tetrahydrobenzo[a]pyrene (anti-BPDE). A 2- to 3-fold increase in the tetraol yield was observed in the presence of nitrite in excess of 1 mM. Sodium azide, an inhibitor of myeloperoxidase and catalase, reduced the nitrite-stimulated metabolism of BP-7,8-diol in PMA-activated leukocytes. Diphenylene iodonium sulphate, a NADPH-oxidase inhibitor, lowered the production of tetraols in PMA-stimulated leukocytes both in the absence and presence of nitrite. Additionally, nitrite markedly enhanced the covalent binding of metabolites derived from [3H](-)-BP-7,8-diol to leukocyte proteins as well as to DNA present extracellularly. The nitrite-stimulated covalent binding to both proteins and DNA was inhibited by the presence of sodium azide. The mechanism underlying the effect of nitrite on the metabolism of BP-7,8-diol to reactive intermediates in PMA-activated human polymorphonuclear leukocytes is not known. However, the results are compatible with a peroxidase-dependent mechanism although other possible pathways may contribute to the enhanced rate of metabolism.
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PMID:Sodium nitrite-stimulated metabolic activation of benzo[a]pyrene 7,8-dihydrodiol in human polymorphonuclear leukocytes. 202 41

Cerastes cerastes venom added in vitro to human whole blood caused a marked inhibitory effect on the luminol-dependent chemiluminescence induced by phorbol myristate acetate (PMA) or opsonized zymosan on phagocyte cells. The inhibitory effect produced by the venom was both dose- and time-dependent when PMA was used as the stimulant of the oxidative burst. Similarly, the venom produced a significant inhibitory effect when added to isolated polymorphonuclear leukocytes (PMNs). Incubation of the isolated PMNs with the highest concentration of the venom used (1000 micrograms/ml), however, did not result in any significant disruption of the membranes of these cells. The effect of the venom on the isolated PMNs was also reversible following washing of the venom-treated cells with phosphate-buffered saline. The scavenger of reactive oxygen species such as superoxide dismutase, catalase and dimethyl sulphoxide potentiated the effect of the venom on the luminol-dependent chemiluminescence of human phagocyte cells. Sodium azide, the myeloperoxidase inhibitor, and sodium benzoate produced a similar potentiating effect. The results suggest that some of the toxicity of the venom may be mediated by an action on the phagocytic immune system.
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PMID:Effect of venom from Cerastes cerastes (Egyptian sand viper) on luminol-dependent chemiluminescence of human blood phagocyte cells. 217 86

We studied in vitro whether human eosinophils (EOS) or neutrophils (PMN), which infiltrate the cardiac lesions of patients with Chagas' disease, have the potential to contribute to pathogenesis upon interaction with Trypanosoma cruzi. Incubation of EOS or PMN with T. cruzi amastigotes in the medium overlaying heart myoblast monolayers for 1-6 hr resulted in myoblast injury denoted by cell detachment (35-85%) accompanied by a small but reproducible degree of cell lysis (less than 15%). Myoblast injury was not due to infection because the amastigotes did not invade these cells. No significant myoblast detachment or lysis occurred when EOS, PMN or parasites were tested separately. Myoblast injury was evidenced by using a radiometric method and was readily confirmed microscopically. Deposits of peroxidase, major basic protein, cationic protein and neurotoxin from EOS granules were found on myoblasts incubated with EOS plus T. cruzi; PMN myeloperoxidase was detected when PMN and parasites were used, implicating granule components from these inflammatory cells in the mechanisms of myoblast injury. These deposits were absent when the myoblasts were incubated with EOS or PMN alone. Sodium azide (EOS peroxidase inhibitor) and the polyanions heparin and dextran sulphate (which neutralize the toxicity of EOS granule cationic proteins) inhibited myoblast injury caused by EOS-T. cruzi co-cultures. Albumin, gelatin (inhibitors of the EOS peroxidase-H2O2-halide system) and catalase (scavenger of H2O2) were also inhibitory. Cell injury caused by PMN-parasite mixtures was inhibited by catalase and by potassium cyanide or sodium azide (myeloperoxidase inhibitors), suggesting that PMN myeloperoxidase mediated cytotoxicity. Myoblast injury appeared to be mediated by EOS and PMN secretion products since supernatants of co-cultures of EOS or PMN with T. cruzi produced detachment, inhibitable by the reagents listed above. These results, and our previous demonstration of deposits of EOS granule components at necrotic chagasic myocardial lesions, point to EOS and PMN as possible contributors to the pathogenesis of Chagas' disease.
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PMID:Interaction of human eosinophils or neutrophils with Trypanosoma cruzi in vitro causes bystander cardiac cell damage. 264 28

Induction of luminol-enhanced chemiluminescence (CL) indicative of reactive oxygen formation was studied in glia cell cultures from newborn mice. A burst of CL could be induced by phorbol myristate acetate, zymosan, and antibody-coated bovine red blood cells, whereas Sendai virus and several other agents known to induce CL in myeloid cells were ineffective. Sodium azide failed to inhibit CL, indicating a myeloperoxidase-independent mechanism of light emission. In parallel experiments we identified the cells binding antibody-coated erythrocytes as macrophages characterized by the reduction of nitroblue tetrazolium and phagocytosis of zymosan and latex particles. Brain macrophages may use reactive oxygen intermediates (ROI) as a mechanism of antimicrobial defence; and, on the other hand, ROI formed by these cells may contribute to immuno-pathology in the brain.
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PMID:Murine glia cells in culture can be stimulated to generate reactive oxygen. 282 45

Peritoneal polymorphonuclear neutrophils (PMN) from mice were tested for their ability to kill the yeast form of Blastomyces dermatitidis (Bd) in vitro and for their fungicidal mechanisms. PMN elicited from immune mice by the intraperitoneal injection of non-viable Bd (referred to as immunologically activated PMN or ActPMN) showed significantly enhanced fungicidal activity in comparison with PMN elicited with thioglycollate medium (ThioPMN) [means = 44.7% (SD 12.8%) and 16.4% (SD 9.2%) killed; n = 14; p less than 0.001]. Production of superoxide anion (O2-) by ActPMN after stimulation with phorbol myristate acetate was enhanced in comparison with production by ThioPMN. Superoxide dismutase, which removes O2-, inhibited ActPMN killing by 75% (p less than 0.001) when added to cultures immediately before challenge with Bd (optimal concentration: 6000 U/ml). Sodium azide, which inhibits myeloperoxidase and scavenges singlet oxygen (1O2), and catalase, which breaks down hydrogen peroxide (H2O2), inhibited ActPMN killing by 64% (p less than 0.001) and 52% (p less than 0.001), with optimal concentrations of 1 mM and 10,000 U/ml, respectively. Two agents that both scavenge 1O2 and antagonise hypochlorous acid (HOCl-), histidine and tryptophan, were also powerful inhibitors of ActPMN killing. Quenchers of hydroxyl radical (.OH), dimethylsulfoxide and sodium benzoate, had less effect, and required higher concentrations. These data suggest that the enhanced killing of Bd by ActPMN involves one or more oxidative mechanisms, and that there is a prominent role for O2-, either directly or as a precursor of other active oxygen species, a probable role for H2O2, and possible roles for 1O2, HOCl-, and .OH.
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PMID:Enhanced oxidative mechanisms in immunologically activated versus elicited polymorphonuclear neutrophils: correlations with fungicidal activity. 282 26

Luminol-dependent photonic burst from phorbol ester-treated single neutrophil was visually investigated by using an ultrasensitive photonic image intensifier microscope. Neutrophils stimulated by phorbol myristate acetate (0.1 microgram/ml) alone produced a negligible level of photonic activities in the presence of luminol (10 micrograms/ml). The additional application of 0.1 microM Ca2+ ionophore A23187 induced explosive changes of photonic burst corresponding to the distribution of neutrophils, and these photonic activities were gradually spread to extracellular space. Sodium azide, which prevents myeloperoxidase activity, inhibited Ca2+ ionophore-induced photonic burst from phorbol ester-treated neutrophil. These findings suggest a prerequisite role of degranulation and myeloperoxidase release in luminol-dependent photoemission from stimulated neutrophils.
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PMID:Luminol-dependent photoemission from single neutrophil stimulated by phorbol ester and calcium ionophore--role of degranulation and myeloperoxidase. 284 75

If H2O2 is one of the major mediators of the 'oxygen effect' in biological systems then catalase, which enzymically decomposes H2O2 should have a significant influence on radiation damage, particularly under oxygenated conditions. The post-irradiation (300 Gy gamma rays) effect of catalase was, therefore, assessed on barley seeds of about 4 per cent moisture content under oxygenated and oxygen-free conditions at varying temperatures. Catalase affords concentration-dependent radioprotection under oxygenated condition at both 25 degrees C and 4 degrees C. The level of protection at 4 degrees C is less than at 25 degrees C. This is obviously due to a decrease in catalase activity at low temperature. Under oxygen-free conditions, catalase enhances radiation damage at 4 degrees C while at 25 degrees C it has no effect. This has been substantiated by data on the frequency of chromosomal aberrations and on peroxidase activity. Sodium azide, a catalase inhibitor, was found to eliminate the radioprotective action of catalase. The study supports the view that the 'oxygen effect' is mediated largely through peroxides in irradiated biological systems. However, the observations made particularly at 4 degrees C under oxygen-free condition seem to involve physicochemical reactions.
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PMID:Post-irradiation modification of oxygen-dependent and independent damage by catalase in barley seeds. 349 10

The myeloperoxidase (MPO)-mediated decarboxylation of amino acids and the MPO-mediated oxidation of methionine, two potential bactericidal mechanisms, were compared. In the presence of the MPO system (MPO, 50 mU/ml; H(2)O(2), 0.1 mM; Cl(-), 75 mM), 50% of alanine (0.1 mM) was decarboxylated, whereas only 5% of methionine (0.1 mM) was decarboxylated. In contrast, under similar conditions, 80% of methionine was oxidized to methionine sulfoxide. Once methionine was oxidized to methionine sulfoxide, it was decarboxylated (75%) by the MPO system. Methionine at 0.1 mM completely inhibited the decarboxylation of alanine, whereas alanine at a concentration 200 times that of methionine had no effect on the MPO-mediated oxidation of methionine. Sodium azide, an MPO inhibitor, inhibited the decarboxylation of alanine and the oxidation of methionine to the same extent. Tryptophan markedly inhibited the oxidation of methionine, whereas histidine stimulated it. Alanine, glycine, and taurine had no effect. In contrast, all of these amino acids and taurine markedly inhibited the MPO-mediated decarboxylation of alanine. NaN(3), tryptophan, and methionine, which inhibited the MPO-mediated oxidation of methionine, also inhibited the killing of Staphylococcus aureus or Klebsiella pneumoniae by the MPO system; whereas histidine, alanine, and glycine, which did not inhibit the oxidation of methionine, had less or no effect on the killing of these two bacteria by the MPO system. Results suggest that methionine is preferentially oxidized to methionine sulfoxide by the MPO system. Once methionine is oxidized to methionine sulfoxide, it is then readily decarboxylated by the MPO system. The agent responsible for the oxidation of methionine may play an important role in the MPO-mediated killing of bacteria.
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PMID:Myeloperoxidase-mediated oxidation of methionine and amino acid decarboxylation. 628 Nov 85


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