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)

Bacteria preincubated with myeloperoxidase (MPO) are more readily killed upon the addition of H2O2 and Cl- than controls not subject to prior incubation. This effect was evidenced by decreased requirements of MPO and H2O2 (to approximately 33%) for equivalent bactericidal activity. MPO adsorbed onto the bacterial surface is not accessible to other competing substrates such as guaiacol and [1(-14)C] alanine. It appears that when MPO is adsorbed to the bacteria, it carries out a coupled reaction in which the activated chlorine directly attacks the bacterial cell surface.
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PMID:Enhanced killing of myeloperoxidase-coated bacteria in the myeloperoxidase-H2O2-Cl- system. 20 33

The human red cell hemolysate was found to have 3-(3',4'-dihydroxphenyl)-L-alanine (L-dopa) peroxidase activity. During the purification of glutathione peroxidase and catalase by ammonium sulfate precipitation, ion exchange chromatography. Sephadex gel filtration, and preparative polyacrylamide disc electrophoresis, the L-dopa peroxidase activity was found to be associated with catalase. Both sodium azide, 8 mM, and 3-amino-1,2,4-triazole, 50 mM, besides inhibiting catalase, inhibited the L-dopa peroxidase activity in each fraction. Ethylenediamine tetraacetic acid (EDTA), 4 mM, had no effect on catalase or L-dopa peroxidase activity, indicating that the oxidation of L-dopa is not a nonenzymatic process mediated by metal ions. Although the electrophoretic mobility of catalase, L-dopa peroxidase, and glutathione peroxidase are similar, a homogeneous preparation of glutathione peroxidase was free of L-dopa peroxidase activity. L-Dopa peroxidase in human red cells was co-purified with catalase.
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PMID:L-Dopa peroxidase activity of human erythrocyte catalase. 40 44

Murine neuroblastoma cultures were labeled externally with the cationic reagent N,N,N-[3H]-trimethylamino-beta-alanyl-N-hydroxy-succinimide ester ([3H]Me3N-beta Ala-NSuc) or with 125I/lactoperoxidase. The cells were labeled in the logarithmic and confluent growth phases as well as in a highly differentiated state following treatment with 2% dimethylsulfoxide. The labeled exterior membrane proteins were analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Major changes in the exterior membrane proteins were observed during maturation and differentiation of the cells. Most of these changes were clonal-specific, while others were common to several clones. Two proteins of Mr 55,000 and 65,000 were labeled by both 125I/lactoperoxidase and Me3N-[3H]-beta Ala-NSuc. The level of labeling was dependent on the clonal lines used and the state of the cell maturation. A group of proteins displaying a molecular weight between 150,000 and 200,000 was found to be related to the transition of a culture from logarithmic to confluent growth phases. An additional protein, with an apparent molecular weight of 95,000, was common to differentiated cells of the two inducible clones used. In general the maturation of logarithmic phase cells into confluent cells resulted in a less complex electrophoretic distribution of the pattern of labeling. After dimethyl-sulfoxide treatment, further reduction in the complexity of the externally labeled proteins was observed.
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PMID:Expression of external-surface membrane proteins in differentiated and undifferentiated mouse neuroblastoma cells. 45 51

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

Wistar male-rats receiving by mouth dianobol for 10 days and 9 months and fed on rations with different proportions of protein were investigated. Dianobol is shown to produce under definite conditions changes in the intensity of the protein synthesis in the muscle tissue and liver of the test animals and also to raise the activity of tryptophan-peroxidase and of alanine-amintransferase, the protein level in the ration being here of substantial importance. With its long-term administration to rats dianobol displays an androgenic effect on the gonads and the supernumerally genitals without exercising any stimulating action on the weight gain.
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PMID:[Influence of methandrostenolone on some aspects of protein metabolism in rats in the context of various protein rations]. 119 13

Degradation of methyl mercury (MeHg) and ethyl Hg (EtHg) with reactive oxygens was studied in vitro by using peroxidase-hydrogen peroxide (H2O2)-halide and rose bengal-ultraviolet light A systems. For this purpose, the direct determination method for inorganic Hg was employed. Both systems could effectively degrade EtHg, and MeHg to some extent. Degradation of MeHg and EtHg with the myeloperoxidase (MPO)-H2O2-chloride system was inhibited by MPO inhibitors (cyanide and azide), catalase, hypochlorous acid (HOCI) scavengers (glycine, alanine, serine and taurine), 1,4-diazabicyclo[2,2,2]octane and 2,5-dimethylfuran, but not by hydroxyl radical scavengers (ethanol and mannitol). Iodide was more effective than chloride as the halide component. Lactoperoxidase (LPO) could substitute for MPO in the iodide, but not the chloride system. With MPO-H2O2-chloride, MPO-H2O2-iodide and LPO-H2O2-iodide systems, we observed the increased degradation of EtHg in deuterium oxide (D2O) medium better than that in H2O medium. The D2O effect upon MeHg degradation was extremely weak. These results suggested that HOCl (or HOI) might be also capable of degrading MeHg and EtHg, besides the hydroxyl radical already reported by us. Singlet oxygen could degrade EtHg but not MeHg.
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PMID:Degradation of methyl and ethyl mercury into inorganic mercury by other reactive oxygen species besides hydroxyl radical. 131 15

Vanadate-dependent peroxidase A.n.I, the main isoenzyme (M(r) = 100 kDa) from the seaweed, Ascophyllum nodosum, contains 2 V per enzyme molecule (as shown by ICP-MS metal analysis) after complete reconstitution with vanadate (V), possibly distributed in a 1:1 ratio between the surface and active site. VO2+ is only weakly associated to the surface of A.n.I. There is no transport channel for VO2+. The EPR spectrum of the reduced holoenzyme is anisotropic (axial) already at room temperature, with EPR parameters similar to those of VO2+ complexes of small model peptides such as Ala-His, Gly-Tyr, Gly-Ser, Gly-Glu, Ser-Gly and Phe-Glu. The complex formation between Ala-His and H2VO4- in water has also been investigated (by 51V NMR); the formation constant at pH 7.2 amounts to 266(28) M-1.
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PMID:(Model) studies on vanadate-dependent bromo/iodoperoxidase from Ascophyllum nodosum. VO2+ is not incorporated into the active site. 131 46

Two site-directed mutants of human promyeloperoxidase, MPO(His416----Ala) and MPO(His502----Ala), have been expressed in Chinese hamster ovary cells and purified. Overall purification yields and apparent molecular masses of the mutant proteins were similar to those of the wild-type enzyme. Both mutant species were analyzed spectroscopically to check the presence of the hemic iron in the proteins and were assayed for peroxidase activity. The data show that substitution of His502 leads to the loss, or to an inappropriate configuration, of the heme together with the loss of activity, suggesting that this residue could be the proximal His involved in the binding to the iron centers. On the other hand, substitution of His416 by alanine had no effect on either of the studied parameters.
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PMID:Site-directed mutants of human myeloperoxidase. A topological approach to the heme-binding site. 132 26

A clone, lambda Prx6.1, coding for a barley seed peroxidase (BP; EC 1.11.1.7), was isolated from a genomic library using a cDNA coding for the barley seed peroxidase, BP 1, as a probe. The nucleotide sequence coded for a BP showing 73% amino acid (aa) sequence identity with BP 1 and less than 50% similarity with other sequenced plant peroxidases. The aa composition is 92% identical to that determined for BP 2 purified from mature barley grains, and therefore the gene product is named BP 2A. The alignment suggests that the coding region is interrupted by a 76-bp intron having the consensuses GT and AG, at the 5' and 3' ends, respectively. Alignment with BP 1 suggests that BP 2A has a leader peptide of 36 aa and the mature protein is 319 aa. Alanine and leucine account for 50% of the residues of the leader peptide. Of the codons used 90% have a C or G in the third position. The promoter shows a putative abscisic acid-response element, 5'-GTACGTGTC, 115 bp upstream from the start codon. The BP 2A-encoding gene was RFLP-mapped on barley chromosome 3, and we suggest for this peroxidase locus the name Prx6.
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PMID:Structure and chromosomal localization of the gene encoding barley seed peroxidase BP 2A. 135 62

Aspirin selectively acetylates Ser-530 of prostaglandin endoperoxide (PGH) synthase-1. This causes inactivation of the cyclooxygenase activity of the enzyme, but does not appreciably affect its peroxidase activity. Although the aspirin-acetylated enzyme is inactive, we found that PGH synthase-1 in which Ser-530 had been replaced with an alanine was catalytically active; accordingly, we proposed that aspirin inhibits cyclooxygenase activity by placing a larger than normal side chain at position 530 thereby interfering with arachidonate binding (DeWitt, D.L., El-Harith, E. A., Kraemer, S. A., Andrews, M. J., Yao, E. F., Armstrong, R. L., and Smith, W. L. (1990) J. Biol. Chem. 265, 5192-5198). As a further test of this hypothesis we have used site-directed mutagenesis and transient expression in cos-1 cells to prepare and characterize five additional substitutions of Ser-530. Consistent with our proposal, the presence of amino acids with bulky side chains at position 530 inhibited cyclooxygenase activity and decreased the apparent affinity of the enzyme for arachidonate. In related work, we characterized a series of mutant PGH synthases-1 having substitutions at residues adjoining Ser-530, including Phe-529, Leu-531, Lys-532, and Gly-533, in order to evaluate the contributions of each residue to cyclooxygenase catalysis. The most significant conclusion of this part of the study is that residues 529-533 all are important for the peroxidase activity as well as the cyclooxygenase activity of PGH synthase-1. Phe-529, in particular, was found to be critical for PGH synthase-1 structure and catalysis; some substitutions at this position led to the production of proteins lacking about 100 amino acids from their COOH termini.
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PMID:Prostaglandin endoperoxide synthase. The aspirin acetylation region. 160 97


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