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)

The formation of HCN from D-histidine in Chlorella vulgaris extracts is shown to be due to the combined action of a soluble protein and a particulate component. Either horse-radish peroxidase (EC 1.11.1.7) or a metal ion with redox properties can be substituted for the particulate component. Ions of manganese and vanadium are especially effective, as are o-phenanthroline complexes of iron. Cobalt ions are less active. The D-amino acid oxidase (EC 1.4.3.3) from kidney and the L-amino acid oxidase (EC 1.4.3.2) from snake venom likewise cause HCN production from histidine when supplemented with the particulate preparation from Chlorella or with peroxidase or with a redox metal ion. The stereospecificity of the amino acid oxidase determines which of the two stereoisomers of histidine is active as an HCN precursor. Though histidine is the best substrate for HCN production, other naturally occurring aromatic amino acids (viz. tyrosine, phenylalanine and tryptophan) can also serve as HCN precursors with these enzyme systems. The relative effectiveness of each substrate varies with the amino acid oxidase enzyme and with the supplement. With respect to this latter property, the particulate preparation from Chlorella behaves more like a metal ion than like peroxidase.
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PMID:Cyanide formation from histidine in Chlorella. A general reaction of aromatic amino acids catalyzed by amino acid oxidase systems. 1 6

The effects of modification of heme carboxylic groups by omega-aminoenantic acid and L-phenylalamine on the peroxidase activity of hemoglobin were studied. For this purpose the peroxidase activities of the original compounds--hemin, hemin-aminoenantic acid, hemin-phenylalanine and hemoglobins prepared from the hemin and globin compounds--hemoglobin, aminoenantyl-hemoglobin and phenylalanine hemoglobin--were determined. The dependence of the peroxidase activity of these compounds on their concentrations and pH was analyzed. It was shown that 40--50% modification of the heme carboxylic groups by amino acids decreases the peroxidase activity of the modified hemins and that of modified hemoglobins reconstructed from these hemins and globin. A decrease of the catalytic activity of the hemoglobin derivatives is due to a lower peroxidase activity (as compared to hemin) of the modified hemins. It is thus concluded that the amino acid modification of the carboxylic groups of heme does not affect the heme-protein interactions in the hemoglobin molecule.
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PMID:[Peroxidase activity of hemoglobin, modified at the carboxylic groups of heme and amino acids]. 3 42

Immunoperoxidase staining for Regan isoenzyme of alkaline phosphatase was performed on cryostat sections of five human tumor tisssues. With a direct immunoperoxidase staining for the localization of Regan isoenzyme at the light and electron microscope levels, sections previously fixed with 0.05 M phosphate-buffered 4% paraformaldehyde were reacted with rabbit antisera to human placenta alkaline phosphatase conjugated to horseradish peroxidase. Comparison of conventional histochemistry and immunohistochemistry for Regan isoenzyme indicated that strong specific immunoperoxidase staining appeared on the cell membrane surface, and a diffuse one, in the cytoplasm of lung and colon cancer tissue cells showing L-phenylalanine-sensitive alkaline phosphatase. No immunoperoxidase reaction was obtained in tumor cells showing sensitivity to L-homoarginine or lacking aklaline phosphatase activity.
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PMID:Direct immunoperoxidase staining for Regan isoenzyme of alkaline phosphatase in human tumor tissues. 18 52

It is commonly postulated that the enzymatic hydroxylation of phenylalanine, tyrosine and tryptophan involves the concomitant oxidation of a tetrahydropteridinic cofactor to an unstable quinonoid product, converted to the initial compound under the catalytic action of dihydropteridine reductase. We now report UV, NMR, mass spectrum and spectroscopic studies of 2-amino-4-hydroxy-6,7-dimethyl-5, 6, 7, 8-tetrahydropteridine oxidation process either by atmospheric O2 or by the H2O2-peroxidase system. No quinonoid form was visualized and, moreover, the spectral characteristics of UV absorbance spectra, initially reported as specific for the quinonoid form, are related to other oxidation products whose formation is explained here.
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PMID:On the mechanism of the tetrahydropteridine cofactor oxidation in aerobic and H2O2-peroxydase media. 47 74

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

In a previous paper we have characterized five plant peroxidases, P1, P2, P3 and P7 of turnip and horseradish isoperoxidase C by peptide mapping studies, and only found two highly homologous sequences present in all. Both contained histidine. The findings supported previous suggestions of two histidine sequences nearthe peroxidase heme prostetic group. In the present paper we present the amino acid sequences around the histidine residues of all four turnip peroxidases, i. e. of 25 residues around the histidine proximal to heme, and 34 residues around the probably distally located histidine, and compare them with the histidine-containing sequences of the complete amino acid sequence of horseradish isoperoxidase C. Substitutions of residues are rare close to these histidines, but more abundant with greater distances. The probably distal sequences of P1, P2, P3, and horseradish peroxidase C all contain two histidine residues, at positions 40 and 42. In P7, however, residue 40 is phenylalanine, a substitution presumably important to its abnormal physio-chemical and enzymic properties. Gel filtration profiles of tryptic digests of the turnip isoperoxidases confirm their previous classification into a P1, and P3 group and a distinct P7 enzyme, but further prove the presence of several sites of carbohydrate attachment in P1, P2 and P3 peroxidases, like in horeseradish peroxidase C which has eight sites. P7 has one such site.
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PMID:Amino-acid sequences of heme-linked, histidine-containing peptides of five peroxidases from horseradish and turnip. 84 40

We previously established that normal articular chondrocytes, like macrophages, express class II major histocompatibility antigens, present antigen, and induce mixed and autologous lymphocyte stimulation. In a recent study using the trapped indicator 2',7'-dichlorofluorescein diacetate, we were able to measure levels of intracellular hydrogen peroxide within normal articular chondrocytes (J Immunol 245:690-696, 1990). In the present study, we utilized the technique of chemiluminescence and the biochemical method of quantitating hydrogen peroxide release to measure the production of reactive oxygen intermediates by articular chondrocytes. Chondrocytes, in suspension or adherent to coverslips, showed luminol-dependent chemiluminescence that was dependent on the number and viability of cells. There was a dose-dependent increase in chemiluminescence in response to soluble stimuli, such as phorbol myristate acetate (PMA), concanavalin A (ConA), and f-Met-Leu-Phe (FMLP). Azide inhibited chemiluminescence, suggesting that the light emission in chondrocytes is myeloperoxidase dependent. The antioxidant, catalase, inhibited chemiluminescence but superoxide dismutase had no effect, suggesting that luminol-dependent chemiluminescence in chondrocytes mostly measured hydrogen peroxide. Chemiluminescence was also observed in fragments of live cartilage tissue, indicating that chondrocytes that are cartilage matrix bound can generate the respiratory burst response. Using the scopoletin oxidation assay, we confirmed the release of increasing amounts of hydrogen peroxide by chondrocytes exposed to interleukin-1, rabbit interferon, and tumor necrosis factor alpha. Tumor necrosis factor alpha had both priming and enhancing effects on reactive oxygen intermediate production by chondrocytes. Reactive oxygen intermediates have been shown to play a significant role in matrix degradation. We suggest that reactive oxygen intermediates produced by chondrocytes play an important role in the degradation of matrix in arthritis.
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PMID:Release of oxygen radicals by articular chondrocytes: a study of luminol-dependent chemiluminescence and hydrogen peroxide secretion. 128 Sep 2

D-Penicillamine inhibited oxidant secretion from human neutrophils after activation by the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe), as assessed by luminol dependent chemiluminescence. In contrast, this drug had little effect on either intracellular oxidant production or lucigenin dependent chemiluminescence activated by the same agonist. The drug was shown to scavenge both H2O2 and HOCl in a cell free luminol chemiluminescence system, though its ability to scavenge HOCl was greater than that for H2O2. Both these oxidants could oxidise the drug, but again HOCl was more potent than H2O2. When D-penicillamine was oxidised by exposure to H2O2 it could no longer serve as a scavenger of secreted oxidants from neutrophils. These data suggest that in vivo the preferential scavenging of HOCl may be important under pathological conditions where secreted myeloperoxidase may be functional.
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PMID:Inhibition of neutrophil oxidant secretion by D-penicillamine: scavenging of H2O2 and HOCl. 131 9

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

The activation of guinea-pig eosinophils was studied by measuring the production of superoxide anion (O2-) and the secretion of eosinophil peroxidase (EPO). Phorbol myristate acetate (PMA), calcium ionophore, plasma-activated zymosan, concanavalin A and recombinant human anaphylatoxin C5a induced the release of varying amounts of EPO. Some of these same activators, as well as platelet-activating factor, and aggregated homologous IgG, either by themselves or after a brief priming of the cells with low concentrations of PMA, also caused the formation of O2-. Formyl-methionyl-leucyl-phenylalanine (FMLP) failed to induce either of these reactions in freshly isolated cells. It was found serendipitously, however, that cells which had been maintained in culture overnight secreted EPO upon challenge with FMLP, and, if they were primed with PMA, they also produced O2-. The conversion from unresponsive to responsive cells ('facilitation') depended on the presence of mononuclear cells or mononuclear cell-conditioned medium in the overnight cultures. Although there also was a shift in the density of the majority of the eosinophils after overnight culture to a density lower than 1.085, this shift was not dependent on the inclusion of monocytes or of monocyte-conditioned medium (MCM) in the cultures and thus was not sufficient to impart responsiveness to FMLP. Responses of eosinophils to other activators were qualitatively unchanged after overnight facilitation. Binding studies using radiolabelled FMLP revealed that, during facilitation, binding of FMLP to guinea-pig eosinophils increased about sixfold overall and suggested the expression of a high affinity receptor. This change may explain the basis for the facilitation phenomenon.
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PMID:FMLP is a potent activator of guinea-pig eosinophils but its activity is dependent on the prior overnight in vitro culture of the cells (facilitation). 131 50


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