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)

Using peroxidase-labelled antibodies, the ultrastructural localization of IgA immunoglobulins in duodenojejunal biopsies from children with active coeliac disease was investigated. Satisfactory penetration of conjugates was achieved by 20 hour-fixation in 4% formaldehyde and 8 hour-incubation of thick frozen sections in the presence of peroxidase-labelled anti-human alpha heavy chain antibody under continuous mild agitation. In normal duodeno-jejunal mucosa, deposits of IgA were observed at the ultrastructural level in the rough endoplasmic reticulum and the perinuclear space of plasma cells and on lateral cell membranes of villous and crypt epithelial cells. In coeliac mucosa, immuno-electron microscopic studies confirmed the increased cell density of IgA immunocytes and revealed heavy deposits of IgA on the basement membrane of surface epithelial cells and the wall of neighbouring blood vessels.
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PMID:Ultrastructural localization of IgA globulins in normal and coeliac intestinal mucosa using immunoenzymatic methods. 79 8

In an attempt to optimize immunosensors operating with an immobilized antibody as binding protein and an analyte-enzyme conjugate as signal generator that is significantly larger in molecular size than the analyte, in a previous communication (Part I) (S.-H. Paek and W. Schramm (1991) Anal. Biochem. 196) we developed mathematical models for the prediction of performance characteristics. These models are compared in this contribution with experimentally obtained results. As an example, a monoclonal antibody to the steroid hormone progesterone has been used as binding protein, an 125I-progesterone derivative, and a progesterone-horseradish peroxidase derivative as tracers for signal generation. A minimum of parameters needs to be experimentally determined to calculate the performance: the amount of immobilized antibody, the diffusion coefficient of antigens, the thickness of the penetration layer, and the on- and off-rates for binding of the antigen to the antibody. We have described simple methods to obtain these data for the labeled antigen and for the unlabeled analyte that does not provide a signal per se. Kinetic binding curves for antigen-antibody complex formation obtained with the mathematical models correlated well with experimentally obtained results for antigens of different sizes. Although equilibrium of the antigen-antibody complex for the enzyme-labeled analyte conjugate requires about 4 h in the absence of free analyte, dose-response curves can be obtained after 5 min and the relative position of these curves does not change significantly after 30 min. Using a total volume of 200 microliters for the analytical procedure in microtiter wells, agitation as a means to accelerate convective diffusion during an incubation period of 30 min is not necessary with the analyte-enzyme conjugate. However, immunosensors using large analyte-enzyme conjugates as signal generators for the detection of small analytes require strict control of the incubation time if operated within short periods of time (less than 30 min).
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PMID:Modeling of immunosensors under nonequilibrium conditions. II. Experimental determination of performance characteristics. 177 82

A quantitative method was developed for the measurement of micromolar quantities of H2O2 produced in Rogosa broth and peptonized milk broth by vaginal strains of lactobacilli isolated from women. The production of substantial amounts reproducibly was dependent on the growth of the organisms in acid media (pH less than or equal to 6.0) under anaerobic or micro-aerophilic conditions with continuous agitation. The addition to the media of the enzyme inhibitor, 3-amino-1,2,4-triazole, with or without catalase sometimes induced the production of H2O2 especially in non-agitated cultures. However, other agents such as concanavalin and o-dianisidine had no enhancing effect, and catalase or peroxidase alone completely inhibited H2O2 production. The H2O2 produced in the acid media was stable for more than a month at 5 degrees C but not in media at pH greater than or equal to 7.0. Of five strains of lactobacilli tested by the quantitative method and by a chromogenic qualitative method (Rogosa-catalase or -per-oxidase agar), three consistently produced H2O2 measurable by the former method, but none did so after growth of the organisms on Rogosa-catalase/peroxidase agar which suggested that the qualitative method was unreliable. The fact that H2O2 was produced in substantial quantities by some strains and not at all by others enabled H2O2-producers and non-producers to be distinguished easily.
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PMID:Comparison of quantitative and qualitative methods of detecting hydrogen peroxide produced by human vaginal strains of lactobacilli. 224 39

The sizes of the alveolar macrophage (AM) and interstitial macrophage (IM) populations in the lungs of adult Fischer-344 rats were determined during steady state. AM labeled with opsonized erythrocytes during an in situ phagocytic assay were lavaged from excised lungs. The lungs were then dispersed into single-cell suspensions with collagenase and mechanical agitation, and the remaining mononuclear phagocytes were identified following a second labeling step. The size of the AM population was 1.3 X 10(7) cells, or approximately equal to 3% of the total lung cell population. The AM were negative for cytoplasmic myeloperoxidase granules. The size of the IM population was 8 X 10(6) cells, or approximately equal to 2% of the total lung cell population. IM were also negative for myeloperoxidase and, like AM, demonstrated marked Fc gamma R-mediated phagocytic activity. The high cell yields (approximately equal to 4 X 10(8) cells/lung; viability, greater than 85%) and the percentages of type II cells (11%) and ciliated epithelial cells (less than 0.5%) indicated the enzymatic dispersion method resulted in a highly efficient and representative sampling of the lung parenchyma. The collagenase method used in this study to disperse the lung cells into single-cell suspensions, in conjunction with additional cell separation techniques, may be of potential use for isolating enriched populations of IM, as well as other lung cell types, for in vitro study.
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PMID:Pulmonary macrophages: alveolar and interstitial populations. 300 Jul 57

We studied the expression of adhesion molecules on the surface of human polymorphonuclear leukocytes (PMNs). The effects of mechanical stimulation were measured with a flow cytometer and pulmonary vascular injury due to accumulation of PMNs in the lungs was assessed by a gravimetric method. The accumulation of PMNs in the lungs was studied by measuring the amount of myeloperoxidase. PMNs were stimulated by gentle agitation in a glass container for 10 s. Mac-1 (CD11b/CD18) was upregulated on the surface of PMNs that were mechanically stimulated. When unstimulated PMNs were exposed to isolated rat lungs, the filtration coefficient did not change from that under baseline conditions. However, when mechanically stimulated PMNs were exposed to isolated rat lungs, the filtration coefficient was about 5 times higher than that measured at baseline. When mechanically stimulated PMNs treated with anti-CD18 antibody were used, the increase in the filtration coefficient was completely blocked. The assay of myeloperoxidase revealed that PMNs stuck to isolated rat lungs only after stimulated PMNs were added. We conclude that when the adhesiveness of PMNs is increased by mechanical stimulation, these cells adhere to pulmonary vessels and increase pulmonary vascular permeability.
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PMID:[Increase in pulmonary vascular permeability caused by increased expression of Mac-1 on the surface of polymorphonuclear leukocytes]. 921 63

Hydrogen peroxide (H2O2) is a well-established cytotoxic agent released by activated neutrophils into the extracellular environment. However, a maximum of only 5 microM H2O2 was detected in the medium when 10(6) neutrophils/ml were activated with opsonized zymosan (OZ), more than 50-fold lower than the concentration of exogenous H2O2 required to produce equivalent killing of a cell line. In addition PMA-activated neutrophils were noncytotoxic, despite the capacity of PMA to generate two- to fourfold as much H2O2 for five times longer. The basis for this discrepancy was explored. NaN3 increased cytotoxicity to >90% only when neutrophils were activated with OZ due in part to inhibition of myeloperoxidase-mediated hydrolysis of H2O2, while catalase completely prevented cytotoxicity of OZ-activated neutrophils. These results indicate that H2O2 was solely responsible for the observed cytotoxicity. OZ-mediated cytotoxicity was prevented by intermittent agitation of the cultures or by the addition of soluble complement receptor type 1, suggesting that a physical association between neutrophils and target cells mediated by OZ was required to generate a cytotoxic environment. Significant numbers of neutrophil-target cell aggregates were observed by microscopic examination only under low hydrodynamic shear conditions. We conclude that the cytotoxic potency of H2O2 produced by neutrophils activated with OZ was due to a localized high concentration of H2O2 to which the target cells were exposed as a result of their labile adherence to OZ. This phenomenon may reflect a mechanism that neutrophils have acquired for maximizing the antimicrobial power of extracellular oxidants toward microbes that escape phagocytotosis.
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PMID:Bridging of neutrophils to target cells by opsonized zymosan enhances the cytotoxicity of neutrophil-produced H2O2. 927 40

The mechanism by which stimulated polymorphonuclear leukocytes and neutrophils (PMNs) damage pulmonary vascular endothelium was investigated. The authors assessed the ability of unstimulated and mechanically stimulated PMNs to adhere to pulmonary endothelial cells and, thereby, alter pulmonary vascular permeability, measured as the pulmonary filtration coefficient (K) and haemodynamics. PMNs were stimulated by gentle agitation in a glass vial for 10 s. Perfusing lungs with the stimulated PMNs (n=6) resulted in significant accumulation of PMNs within the lungs, assessed by myeloperoxidase levels, and elicited a 4-fold increase in K and a 2-fold increase in pulmonary vascular resistance as compared to lungs perfused with unstimulated cells (n=6). The increases in K were completely blocked by GF109203X, a protein kinase C inhibitor (n=6); however, GF109203X only partially attenuated the increase in vascular resistance and had little effect on the accumulation of stimulated PMNs. An agonist of protein kinase C, phorbol myristate acetate, elicited dose dependent increases in both K and pulmonary vascular resistance even in the absence of PMNs (n=6). These findings indicate that the increases in pulmonary filtration coefficient and pulmonary vascular resistance induced by polymorphonuclear neutrophils result from endothelial cell injury mediated by activation of protein kinase C within the endothelial cells themselves.
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PMID:Endothelial signal transduction system enhances neutrophil-induced pulmonary vascular permeability. 1075 36

Liginin peroxidase (ligninase) of the white rot fungus Phanerochaete chrysosporium Burdsall was discovered in 1982 as a secondary metabolite. Today multiple isoenzymes are known, which are often collectively called as lignin peroxidase. Lignin peroxidase has been characterized as a veratryl alcohol oxidizing enzyme, but it is a relatively unspecific enzyme catalyzing a variety of reactions with hydrogen peroxide as the electron acceptor. P. chrysosporium ligninases are heme glycoproteins. At least a number of isoenzymes are also phosphorylated. Two of the major isoenzymes have been crystallized. Until recently lignin peroxidase could only be produced in low yields in very small scale stationary cultures owing to shear sensitivity. Most strains produce the enzyme only after grown under nitrogen or carbon limitation, although strains producing lignin peroxidase under nutrient sufficiency have also been isolated. Activities over 2000 U dm(-3) (as determined at 30 degrees to 37 degrees C) have been reported in small scale Erlenmeyer cultures with the strain INA-12 grown on glycerol in the presence of soybean phospholipids under nitrogen sufficiency. In about 8 dm(3) liquid volume pilot scale higher than 100 U dm(-3) (as determined at 23 degrees C) have been obtained under agitation with immobilized P. chrysosporium strains ATCC 24725 or TKK 20512. Good results have been obtained for example with nylon web, polyurethane foam, sintered glass or silicon tubing as the carrier. The immobilized biocatalyst systems have also made large scale repeated batch and semicontinuous production possible. With nylon web as the carrier, lignin peroxidase production has recently been scaled up to 800 dm(3) liquid volume semicontinuous industrial production process.
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PMID:Production of Phanerochaete chrysosporium lignin peroxidase. 1454 34

The white-rot fungus Coriolus hirsutus strain 075 excretes considerable amounts of laccase and Mn-peroxidase into culture broth over a brief production time. The effects of agitation speed, temperature, aeration and inoculum amount on laccase production using a 10-l fermentor were studied. The optimum fermentation conditions were a 15% inoculum, an aeration rate of 0.88 vvm, an agitation speed of 160 rpm, and a temperature of 28 degrees C. By optimizing the fermentation conditions, the laccase activity reached 80+/-3 U/ml in 3 d and the purified enzyme output was 30 mg/l. The laccase and Mn-peroxidase were purified by means of isoelectrofocusing and ion-exchange chromatography. The pIs of the laccase isoenzymes were 4.2 and 4.5. Mn-peroxidase had only one isoenzyme with a pI of 3.2. The optimum pH was 4.5 for laccase with syringaldazine as the substrate and 5.0-5.3 for Mn-peroxidase with Mn(+2) and H2O2 as the substrates. The laccase and Mn-peroxidase retained 50% of their activities at 50 degrees C after 55 h and 12 h of incubation time, respectively.
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PMID:Laccase and Mn-peroxidase production by Coriolus hirsutus strain 075 in a jar fermentor. 1623 31

A highly basic peroxidase isoenzyme was shown to be released to the culture medium of tomato (Lycopersicon esculentum) hairy roots grown in Murashige-Skoog (MS) liquid medium when it was supplemented with 100 mM NaCl. In this paper we demonstrate that this enzyme is ionically bound to cell walls and that the release was a consequence of the continuous agitation of the tissue in a high ionic strength medium with salt addition. In order to establish the physiological role of this isoenzyme we partially purified it, and we analysed its kinetic properties as coniferyl alcohol peroxidase. The peroxidase isoenzyme showed a high catalytic efficiency for this substrate, which suggests that it would be associated with the ligno-suberization process. To confirm the involvement of this isoenzyme in that process, we studied the pattern of ligno-suberization of the tissue under different conditions of growth. Our results suggest that this basic peroxidase would be indeed involved in ligno-suberization since its leakage from cell walls, induced by 100 mM NaCl in liquid MS, caused less ligno-suberization of exo and endodermis. On the contrary, more ligno-suberization was seen in cell walls when the hairy roots were grown in a salt-supplemented MS solid medium without contact with it, a condition in which the release of the isoenzyme would be avoided. Thus, through the changes produced by the release of the enzyme from its site of action, we could demonstrate the physiological role of this peroxidase in the processing of root cell walls, being part of control mechanisms of ion and water fluxes through the root.
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PMID:Changes in ligno-suberization of cell walls of tomato hairy roots produced by salt treatment: the relationship with the release of a basic peroxidase. 1661 85


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