Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glutathione and cysteine bind to the heme of lactoperoxidase, thereby causing a red shift of the Soret band which is reversed upon addition of iodide or guaiacol, two substrates for lactoperoxidase. The rate of formation of the enzyme-thiol complex is enhanced by diiodotyrosine. Binding of diiodotyrosine to lactoperoxidase does not cause a shift of the Soret band which indicates binding to the protein of the enzyme. At neutral pH and low ionic strength, lactoperoxidase is adsorbed on insolubilized diiodotyrosine (diiodotyrosine-agarose). It can be eluted at slightly increased ionic strength which shows that the binding is weak. In the presence of 5 X 10(-4) M glutathione, however, the binding of the enzyme to diiodotyrosine-agarose becomes much stronger so that a high salt concentration is required for elution. Lactoperoxidase is also adsorbed on insolubilized thiols (thiol-agarose). The presence of diiodotyrosine is not required for strong binding. A simple method for the preparation of lactoperoxidase from milk by affinity chromatography is based on the interactions of the enzyme with the two ligands, thiols and diiodotyrosine.
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PMID:Interaction of lactoperoxidase with thiols and diiodotyrosine. 3 12

Exogenous ammonium ions (NH(4) (+)) and amine compounds had a profound influence on the antibacterial activity of the myeloperoxidase-hydrogen peroxide-chloride system against Escherichia coli. The rate of killing increased in the presence of NH(4) (+) and certain guanidino compounds and decreased in the presence of alpha-amino acids, polylysine, taurine, or tris (hydroxymethyl) aminomethane. Myeloperoxidase catalyzed the oxidation of chloride to hypochlorous acid, which reacted either with bacterial amine or amide components or both or with the exogenous compounds to yield chloramine or chloramide derivatives or both. These nitrogen-chlorine derivatives could oxidize bacterial components. Killing was correlated with oxidation of bacterial components. The rate of oxidation of bacterial sulfhydryls increased in the presence of the compounds that increased the rate of killing and decreased in the presence of the other compounds. The reaction of HOCl with NH(4) (+) yielded monochloramine (NH(2)Cl), which could be extracted into organic solvents. The N-Cl derivatives of bacterial components or of polylysine, taurine, or tris(hydroxymethyl)aminomethane could not be extracted. The effect of NH(4) (+) on killing is attributed to the ability of NH(2)Cl to penetrate the hydrophobic cell membrane and thus to oxidize intracellular components. Polylysine, taurine, and tris(hydroxymethyl)aminomethane formed high-molecular-weight, charged, or polar N-Cl derivatives that would be unable to penetrate the cell membrane. These results suggest an important role for leukocyte amine components in myeloperoxidase-catalyzed antimicrobial activity in vivo.
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PMID:Myeloperoxidase-hydrogen peroxide-chloride antimicrobial system: effect of exogenous amines on antibacterial action against Escherichia coli. 3 30

Degradation of myelin basic protein during incubations with high concentrations of horseradish peroxidase has been demonstrated [Johnson & Cammer (1977) J. Histochem. Cytochem.25, 329-336]. Possible mechanisms for the interaction of the basic protein with peroxidase were investigated in the present study. Because the peroxidase samples previously observed to degrade basic protein were mixtures of isoenzymes, commercial preparations of the separated isoenzymes were tested, and all three degraded basic protein, but to various extents. Three other basic proteins, P(2) protein from peripheral nerve myelin, lysozyme and cytochrome c, were not degraded by horseradish peroxidase under the same conditions. Inhibitor studies suggested a minor peroxidatic component in the reaction. Therefore the peroxidatic reaction with basic protein was studied by using low concentrations of peroxidase along with H(2)O(2). Horseradish peroxidase plus H(2)O(2) caused the destruction of basic protein, a reaction inhibited by cyanide, azide, ferrocyanide, tyrosine, di-iodotyrosine and catalase. Lactoperoxidase plus H(2)O(2) and myoglobin plus H(2)O(2) were also effective in destroying the myelin basic protein. Low concentrations of horseradish peroxidase plus H(2)O(2) were not active against other basic proteins, but did destroy casein and fibrinogen. Although high concentrations of peroxidase alone degraded basic protein to low-molecular-weight products, suggesting the operation of a proteolytic enzyme contaminant in the absence of H(2)O(2), incubations with catalytic concentrations of peroxidase in the presence of H(2)O(2) converted basic protein into products with high molecular weights. Our data suggest a mechanism for the latter, peroxidatic, reaction where polymers would form by linking the tyrosine side chains in basic-protein molecules. These data show that the myelin basic protein is unusually susceptible to peroxidatic reactions.
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PMID:Proteolytic and peroxidatic reactions of commercial horseradish peroxidase with myelin basic protein. 7 59

Lactoperoxidase-catalysed iodination was used to label intestinal epithelial cell sheets with 125I. The iodination was carried out under conditions that allowed little penetration of lactoperoxidase into the cells and membrane-bound 125I therefore provided an effective marker for following plasma-membrane fragments through subcellular-fractionation procedures. 2. After homogenization and isopycnic zonal centrifugation through sucrose gradients two peaks of membrane-bound 125I were detected. One coincided with brush border enzymes such as alkaline phosphatase, disaccharidases and L-leucine B-naphthylamidase, whereas the other was coincident with the major peak of (Na++K+)-stimulated ATPase (adenosine triphosphatase), which has been thought to be concentrated in the basolateral plasma membranes of these cells. Neither peak of 125I reflected the distribution of any marker for an intracellular organelle. 3. A larger proportion of the (Na++K+)-stimulated ATPase, and thus of the basolateral plasma-membrane material, was found in a crude 'mitochondrial' fraction. It was not readiily separated from mitochondria by conventional techniques of subcellular fractionation. 4. Treatment of the 'mitochondrial' fraction with digitonin increased the density of basolateral plasma membrane but had little effect on mitochondrial density. A purified preparation of digitonin-loaded basolateral plasma membranes was isolated at a density of 1.20-1.22 by isopycnic centrifugation. 5. The enzymic composition of this preparation of basolateral plasma membranes is compared with previous preparations isolated from intestinal mucosal 'scrape' materials and from isolated cells.
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PMID:Basolateral plasma membranes of intestinal epithelial cells. Identification by lactoperoxidase-catalysed iodination and isolation after density perturbation with digitonin. 12 58

A brain biopsy obtained from a twenty-eight month old boy with ceroidlipofuscinosis was studied by light and electron microscopy. There were widespread intracellular deposits of autofluorescent material taking the fat stains. Cytoplasmic inclusions were plentiful in neurons, astrocytes, oligocytes, M cells and vascular elements. Their substructure ranged from that of variably dense aggregates of essentially homogeneous or granular appearance to that of miscellaneous collections of lamellar pairs and/or tubular structures of variable length. Stacks of 2 to 4 linear profiles with a curved outline were rarely seen and then almost exclusively inside cytosomes of endothelial cells. Similar observations were made in peripheral nerve, skin and liver biopsies. The granules of peripheral blood neutrophilic leukocytes were unremarkable. A small percentage of lymphocytes contained granular cytoplasmic bodies not unlike those known to be an ordinary feature of some lymphocytes of the average blood sample. However, a certain resemblance between these bodies and some of the cytosomes seen in the patient's tissues was also apparent. Myeloperoxidase activity was tested with paraphenylenediamine and was found to be normal on two occasions. The patient's age, cytosome morphology and distribution and results of peroxidase assay add special interest to this case of generalized ceroidlipofuscinosis. However, none of these features, either singly or in combination, warrants creation of a distinct subtype within this group of disorders. Myeloperoxidase deficiency is probably just another phenotypical marker of some patients with generalized ceroidlipofuscinosis rather than the genetic defect of Batten disease.
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PMID:Cytosome morphology and distribution of generalized ceroidlipofuscinosis in a twenty-eight month old boy with normal myeloperoxidase activity. 17 May 59

Localization of peroxidatic catalase in human peripheral blood leukocytes was accomplished by the assessment of alkaline diaminobenzidine reaction in the cytoplasmic granules of normal and acatalasemic leukocytes. A modified cytochemical procedure of Novikoff and Goldfischer (Novikoff AB, Goldfischer S: J Histochem Cytochem 17:675, 1969) and of Fahimi (Fahimi HD:J Cell Biol 43:275, 1969) was employed to improve the specificity of alkaline diaminobenzidine test for catalase. Diaminobenzidine-positive reaction for peroxidative catalase was observed in large and medium-sized granules in the cytoplasm of normal neutrophils, but a striking and notable absence of this reaction was observed in acatalasemic neutrophils. The test for myeloperoxidase, with the diaminobenzide reaction performed at neutrality, disclosed positively stained granules in both normal and acatalasemic neutrophils. Similarities in size and configuration of the positively stained granules for these enzymes suggest that catalase is sequestered in organelles which may be primary or azurophilic granules. Myeloperoxidase has been shown to be localized in the primary granules by others. It is possible that catalase and myeloperoxidase may be sequestered together or separately in these granules, but the present data do not permit us to draw this distinction. The ultrastructural localization of peroxidatic catalase and myeloperoxidase has been attempted in eosinophils, lymphocytes, and platelets, and the observations are compared with those of neutrophilic granules. The localization of peroxidatic catalase in monocytes could not be assessed satisfactorily because of the difficulties encountered in proper sampling of these cells.
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PMID:Ultrastructural localization of peroxidatic catalase in human peripheral blood leukocytes. 17 25

Cationic proteins purified from human polymorphonuclear leukocyte granules exert a cytotoxic effect on mammalian tumor cells. This effect is time and concentration dependent, is inhibited by the anionic agent heparin, and is enhanced by preheating the cationic proteins. Other strongly basic proteins (histone, protamine) also exhibited cytotoxic activity. Myeloperoxidase isolated from human leukocytes is cytotoxic when combined with H2O2 and chloride. Under these conditions, the potency of the myeloperoxidase-mediated system is greater than that of the cationic proteins.
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PMID:Cytotoxicity for tumor cells of cationic proteins from human neutrophil granules. 18 2

Myeloperoxidase, restricted to primary granules, and lactoferrin, restricted to secondary granules, were determined in plasma and neutrophils of peripheral blood in chronic granulocytic leukaemia (CGL). Plasma myeloperoxidase was increased 2-3 times while plasma lactoferrin increased 2-8 times. This discrepancy indicates different modes of release or elimination. A correlation was found between the leucocyte count and plasma myeloperoxidase or lactoferrin. A correlation was also found between cellular and plasma levels of lactoferrin but not for myeloperoxidase indicating the source for plasma lactoferrin to be circulating leucocytes, which may not be the case for plasma myeloperoxidase. Decreased neutrophil lactoferrin was found in 71% of the CGL cases while myeloperoxidase was decreased in 18%. Serial studies on individual CGL subjects showed low cellular lactoferrin during phases with rapidly expanding leucocytosis indicating defective maturation of neutrophils or abnormal release because of prolonged intravascular life-span.
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PMID:Myeloperoxidase and lactoferrin of blood neutrophils and plasma in chronic granulocytic leukaemia. 19 Jun 73

Myeloperoxidase, H2O2, and a halide form a potent antimicrobial and cytotoxic system of the polymorphonuclear leukocyte. A cytotoxic effect of this system on human blood leukocytes is demonstrated, employing 51Cr release and dye exclusion assays. Cytotoxicity is dependent on enzymatically active myeloperoxidase, H2O2, or a peroxide-generating enzyme system and either chloride or iodide. Cell damage is rapid, with maximal levels of 51Cr release occurring within 30--60 min. Approximately equal sensitivity to the peroxidase system is observed for polymorphonuclear leukocytes and mononuclear leukocytes. Since myeloperoxidase and H2O2 are released from polymorphonuclear leukocytes under certain conditions, such as during particle ingestion, it is suggested that peroxidase-mediated leukocyte injury may be an important feature of the inflammatory response.
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PMID:Myeloperoxidase--H2O2--halide system: cytotoxic effect on human blood leukocytes. 19 41

A case is reported of hereditary myeloperoxidase deficiency in a diabetic patient suffering from a Candida albicans hepatic abscess. Myeloperoxidase (MPO) is completely absent from the neutrophils and monocytes, although it is present in the eosinophils. Functional granulocyte studies have revealed normalchemotactic and phagocytic activity, although the bacterial activity is partially diminished with regard to Staphylococcus aureus and is almost nil with regard to Candida albicans. The granulocytic metabolism, when stimulated by zymosan, is characterized by greatly increased oxygen consumption. Genetic investigations have been conducted in 28 members of the patient's family. Cyto- and biochemical determination of MPO is clearly diminished in close relatives of the patient. Genetic analysis indicates recessive autosomal transmission with variable expressivity of the gene for the heterozygote state.
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PMID:[Hereditary myeloperoxidase deficiency. Clinical, biological and genetic study]. 19 39


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