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)

Synthesized N protein of vesicular stomatitis virus (VSV) is associated with replicated viral genomes in the infected cells. The cytoplasmic side of cell membranes was examined by quick-freezing and deep-etching replica method, in order to clarify the localization of VSV genomes. Control or infected monolayer Vero cells were fixed in 2% paraformaldehyde, scraped and centrifuged to make pellets. A drop of the cell pellet was put between two glass coverslips, which were coated with 3-aminopropyl triethoxy silane and glutaraldehyde. The cells were consequently split open and postfixed in the mixture of glutaraldehyde and paraformaldehyde. Some inside-out cell membranes on the coverslips were immunostained with anti-N monoclonal antibody directly coupled to gold particles. Others were immunostained with anti-N monoclonal antibody and rabbit anti-mouse IgG coupled to peroxidase and fixed again in glutaraldehyde. They were incubated in diaminobenzidine and hydrogen peroxide solution for 1 min. All of them were infiltrated with 10% methanol in distilled water and quickly frozen in a mixture of isopentane and propane cooled by liquid nitrogen. Such preparations were deep-etched and shadowed by platinum and carbon. Although many cell organelles were found to be associated with the cytoplasmic side of cell membranes in the normal Vero cells, few cell organelles were attached to it in the infected cells. On the contrary, special strand structures were identified, which could be immunostained with anti-N monoclonal antibody. It is concluded that platinum replicas have sufficient resolution to identify the VSV genomes coated with N protein and that these nucleocapsids can be associated with the cytoplasmic side of cell membranes in the infected cells.
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PMID:Immunocytochemical study on the cytoplasmic side of cell membranes infected with vesicular stomatitis virus by quick-freezing and deep-etching replica method. 299 6

1-Naphthol was metabolised by horseradish peroxidase (HRP) in a H2O2-dependent reaction to methanol-soluble and covalently bound products. Spectrophotometric and electron spin resonance (ESR) studies established that HRP catalysed the one electron oxidation of 1-naphthol to naphthoxy or a naphthoxy-derived radical. Inclusion of glutathione (GSH) in the reaction caused a dose-dependent inhibition of covalent binding and an increase in the amount of unmetabolised 1-naphthol present at the end of the incubation. gamma-Radiolysis studies suggest that this is due to the reduction of naphthoxy radicals by GSH yielding 1-naphthol and GS.. In agreement with this, HRP-catalysed-oxidation of 1-naphthol in the presence of GSH, was found to stimulate oxidised glutathione (GSSG) formation.
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PMID:Peroxidase activation of 1-naphthol to naphthoxy or naphthoxy-derived radicals and their reaction with glutathione. 301 37

Catalase is an enzyme which can function either in the catabolism of hydrogen peroxide or in the peroxidatic oxidation of small substrates such as ethanol, methanol, or elemental mercury (Hg0). It has been reported that native catalase can peroxidatically oxidize larger organic molecules (e.g. L-dopa) and that catalase maintained at alkaline pH for various lengths of time demonstrates an increase in peroxidase activity using guaiacol as substrate. We have shown, by using two distinct methods of H2O2 introduction for measuring peroxidase activity, that native catalase shows no peroxidatic activity toward these larger organic molecules. We have also shown, through the use of these peroxidase assays and by enzyme absorption spectra, that the peroxidase activity attributed to catalase maintained at alkaline pH is a catalytic but not enzymatic activity associated with a hematin group attached to a denatured catalase monomer. Possible mechanisms for the catalytic and peroxidatic modes of action of catalase involving hydride-ion transfer are discussed.
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PMID:Analysis of the peroxidatic mode of action of catalase. 301 41

We have developed immunocytochemical staining methods for the simultaneous phenotypic and karyotypic characterization of individual cells. Following a mild hypotonic pretreatment, isolated cells are cytocentrifuged on poly-L-lysine coated slides, fixed in formol buffered acetone, and subsequently labeled with monoclonal antibodies utilizing indirect immunoenzymatic staining procedures with horseradish peroxidase (HRP) or alkaline phosphatase monoclonal anti-alkaline phosphatase (APAAP) as second antibodies. Preparations are refixed consecutively in methanol and 45% acetic acid and counterstained with either "Stains-all" (HRP labeled preparations) or Giemsa (APAAP labeled preparations). C-banding or weak G-banding, which allows the identification of individual chromosomes, can be induced in labeled as well as unlabeled mitotic cells by Ba(OH)2 and/or 2 X SSC treatment after refixation, respectively. Our method has been successfully tested with a variety of monoclonal antibodies against lymphoid, myeloid, erythropoietic, and thrombopoietic cell surface antigens. It is fast, allows the adjustment of the intensity of cell surface staining, and results in permanent preparations suitable for light microscopic analysis.
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PMID:Immunoenzymatic staining methods for simultaneous demonstration of chromosomes and cell surface markers. 303 39

Plasma membranes of Plasmodium chabaudi-infected erythrocytes contain seven major neoproteins with apparent molecular masses of 154, 145, 90, 72, 67, 52, and 33 kDa, respectively. These neoproteins, with the exception of the two larger ones, can be metabolically labelled with [14C]isoleucine. The seven neoproteins are antigenic as revealed by Western blotting using hyperimmune sera obtained from two different mouse strains. None of the parasite proteins is accessible from the outside in intact P. chabaudi-infected erythrocytes as determined by lactoperoxidase-mediated radioiodination, indirect immune fluorescence microscopy, or post-embedding immunoelectron microscopy. These methods, however, identify parasite proteins in host cell plasma membranes when the latter are artificially changed either during isolation or by methanol fixation. We conclude therefore that parasitic proteins are cryptically arranged in intact host cell plasma membranes of P. chaubaudi-infected erythrocytes.
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PMID:Cryptic disposition of antigenic parasite proteins in plasma membranes of erythrocytes infected with Plasmodium chabaudi. 304 Dec 77

Various fixatives and treatments such as acetone, methanol, Bouin fixative, modified Bouin fixative, 10% Formalin, modified methacarn, periodate-lysine-paraformaldehyde, acetone-methyl benzoate-xylene, and EDTA were evaluated for their effect on the immunoreactivity of Coxiella burnetii in paraffin-embedded tissues by using the avidin-biotin-peroxidase complex and the peroxidase-antiperoxidase procedure. C. burnetii antigen was shown to be present in liver, spleen, and uterus tissues of experimentally infected mice by all methods of fixation and treatment. A positive immunoreaction was seen in cytoplasmic vacuoles of macrophages, as extracellular rod-shaped organisms, and as residual particulate extra- and intracellular debris. Immunoreactivity and cellular preservation, however, varied substantially with the individual fixatives. Optimal immunostaining of C. burnetii was achieved by EDTA treatment and Bouin and acetone fixation. The avidin-biotin-peroxidase technique proved to be slightly more sensitive than the peroxidase-antiperoxidase procedure when primary antibody dilution was used as the criterion for sensitivity.
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PMID:Evaluation of different fixatives and treatments for immunohistochemical demonstration of Coxiella burnetti in paraffin-embedded tissues. 305 60

Binding sites for horseradish peroxidase (HRP), with unusual properties, were detected on the surface of cultured and isolated cells after the cells (on cover slips) had been quickly dried, fixed in cold methanol, and post-fixed in a paraformaldehyde solution. The reaction for surface-bound HRP was suppressed by micromolar concentrations of glycoproteins such as invertase, equine luteinizing hormone (eLH) or human chorionic gonadotropin (hCG). The reaction was also suppressed by 20 mM CDP, UDP, GTP, NAD, and ribose 5-phosphate. Two to six times higher concentrations of GMP, fructose 1-phosphate, galactose 6-phosphate, mannose 6-phosphate, fructose 6-phosphate, and glucose 6-phosphate were required to suppress the binding reaction. AMP, ATP, heparin, mannan, and eight non-phosphorylated sugars showed relatively low competing potencies but fucoidin and alpha-lactalbumin were strong inhibitors. No addition of Ca2+ was required for the binding of HRP to the cell surface. However, calcium-depleted, inactive HRP did not compete with the binding of native (calcium-containing) HRP whereas H2O2-inactivated HRP suppressed the binding. GTP, NAD, ribose 5-phosphate, and EGTA accelerated the release of previously-bound HRP from the cell surface whereas glycoproteins (invertase, eLH, and hCG) did not do so. Addition of Ca2+ to GTP, NAD, ribose 5-phosphate or to EGTA prevented the accelerated release of HRP from the cell surface. It is suggested that calcium, present either in the surface membrane or in HRP itself, is involved in the binding of HRP to the cell surface and in the inhibition of binding by GTP, NAD, and ribose 5-phosphate. It is also suggested that alpha-lactalbumin, GTP, UDP, and CDP compete with the binding of HRP to a glycosyltransferase on the cell surface.
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PMID:Unusual binding sites for horseradish peroxidase on the surface of cultured and isolated mammalian cells. Suppression of binding by certain nucleotides and glycoproteins, and a role for calcium. 309 11

Naturally contaminated corn and cottonseed samples were screened for aflatoxin B1 (AFB1) by a direct competitive enzyme-linked immunosorbent assay (ELISA). Samples were blended 5 min in an extraction solvent of methanol-water-dimethylformamide (70 + 29 + 1) and filtered. Filtrates were assayed by direct competition between AFB1 in the corn and cottonseed samples and AFB1-peroxidase conjugate for binding to specific antibody adsorbed to a solid phase microtiter plate. Standard curves prepared using the extract of AFB1-free corn and cottonseed samples, and extraction solvent only, showed negligible interference by the sample extract in the performance of ELISA. The AFB1 content in corn and dehulled cottonseed samples as determined by ELISA ranged from 7 to 422 micrograms/kg and 7 to 3,258 micrograms/kg, respectively. When ELISA estimates of AFB1 in corn were compared with values obtained by thin layer chromatography (CB method), the correlation coefficient (n = 10) was 0.95. Average interassay and subsample coefficients of variation for ELISA in corn were 21.4 and 22.0%, respectively. When ELISA estimates of AFB1 in cottonseed were compared with values obtained by liquid chromatography (Pons method), the correlation coefficient (n = 15) was 0.96. Using this ELISA, 36 duplicate sample extracts can be screened for AFB1 in less than 2 h.
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PMID:Enzyme-linked immunosorbent assay of aflatoxin B1 in naturally contaminated corn and cottonseed. 309 11

The effects of temperature (20 to -38 degrees C), pressure (normal pressures to 1.2 kbar) and solvent (water, 60% DMSO and 50% methanol) on the reaction of hydrogen peroxide or ethyl peroxide with horseradish peroxidase were studied. The formation of compound I was followed at 403 nm in a stopped flow apparatus adapted for high pressure and low temperature work. As with the alkaline form (Job and Dunford 1978), the neutral form of the peroxidase binds peroxide substrates in two steps. It was the combined use of organic solvents and low temperatures which revealed saturation kinetics: (Formula: see text) compound I, where E = horseradish peroxidase and S peroxide substrate. In water and organic solvents at temperatures above -10 degrees C, K1 was too small and k2 too large to be measured, here K1 X k2 was obtained. k-2 was too small for measurement under all conditions. Whereas K1 was insensitive to the peroxide substrate and solvent composition, k2 was very sensitive. The thermodynamic parameters delta H, delta S and delta V for K1 and k2 were obtained under different experimental conditions and the data are interpreted within the available thermodynamic theories.
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PMID:Thermodynamics of the two step formation of horseradish peroxidase compound I. 359 44

Upon the addition of hydrogen peroxide or ethyl hydroperoxide to sperm whale metmyoglobin (MbIII) in the presence of ethanol, MbIII was converted to oxymyoglobin (MbIIO2) under aerobic conditions and carboxymyoglobin (MbIICO) under CO-saturated conditions. MbIIO2 and MbIICO were also formed when ethanol was added to ferryl myoglobin (MbIV) which had been formed from the reaction of MbIII with hydrogen peroxide. From the stoichiometry, the primary reaction was formulated as follows. MbIV + ethanol----MbII + acetaldehyde The reaction was optimal at pH 7.0-7.5. Sperm whale ferryl myoglobin was reduced less effectively by methanol and n-butanol, but not at all by sec- and tert-butanols. The reduction of ferryl hemoproteins by ethanol was slower with horse heart myoglobin and was not observed with bovine hemoglobin or horseradish peroxidase.
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PMID:The 2-electron reduction of sperm whale ferryl myoglobin by ethanol. 378 63


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