Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PEROXIDASES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1983

Immunoelectron microscopy of the bone marrow mononuclears labelling with rabbit anti-mouse brain serum using peroxidase-anti-peroxidase method.

Ultrastructural features of mouse bone marrow mononuclears (BMM) labelled with peroxidase-anti-peroxidase (PAP) complex using rabbit anti-mouse brain serum (RAMBS) and rabbit anti-mouse brain serum, absorbed with thymocytes (RAMBST) were investigated. After incubation of cells with RAMBST which have high activity against mouse pluripotent hemopoietic stem cells (CFUs) about 0.6% of BMM were labelled. According to their fine structure these cells were similar to those described earlier as presumptive pluripotent hematopoietic stem cells (PHSC). After incubation with RAMBS 1.9% of BMM were labelled, including cells marked by RAMBST and typical small lymphocytes with ultrastructure of T-lymphocytes.

Animals↗
PubMed1978

Demonstration of the Fc-receptor of blood cells by soluble peroxidase-anti-peroxidase (PAP) complexes.

The Fc-receptor of normal human leukocytes, of CLL-cells, and of hematopoietic cell lines was demonstrated with soluble peroxidase-anti-peroxidase (PAP) complexes. In about 9% of normal lymphocytes an almost continuous, strong labeling of the cell membrane was established. Some of these lymphocytes were characterized by a peculiar uniform fine structure. The percentage of PAP-labeled monocytes was in the range of 25%, neutrophils nearly 100%, eosinophils 0%, CLL-cells 10%. Labeled portions of the membrane were interiorized from monocytes. The lymphoid cell-line Daudi established from a Burkitt's lymphoma appeared almost negative, the cell line K562 established from a myeloid leukemia in 75% of the cells strongly positive. PAP-labeling was not influenced by preincubation with trypsine or with neuraminidase; it was negative when PAP-F(ab)2 was used. Results of PAP-labeling were not always in agreement with EA-rosettes or with agg-Ig.

Binding Sites↗
PubMed1986

A new method for identification of the animal origin of mosquito bloodmeals by the immunobinding of peroxidase-anti-peroxidase complexes on nitrocellulose.

A method is described for identification of the animal origin of mosquito bloodmeals (MBM). The immunoassay is named DOT-PAP, it makes use of nitrocellulose as solid phase and of peroxidase-anti-peroxidase soluble complexes as detectors. DOT-PAP includes a built-in absorbing system to remove possible cross-reactivities. The sensitivity of the assay is higher than that of precipitin test or ELISA, and it dispenses with machineries for the reading of results. The method requires nanogram amounts of antigen, therefore it lends itself to the identification of incomplete MBM and of 28 h digested MBM as well. The assay can be applied to different hematophagous arthropods and the small volumes of antigen used allow to scan a vast array of possible animal sources on the same bloodmeal.

Animals↗
PubMed1985

Congenital toxoplasmic retinochoroiditis in the mouse--the use of the peroxidase anti-peroxidase method to demonstrate Toxoplasma antigen.

The peroxidase anti-peroxidase immunocytochemical staining method has been used to demonstrate Toxoplasma antigen within paraffin-embedded sections of the eyes of mice congenitally infected with Toxoplasma. Intact Toxoplasma tissue cysts were demonstrated within the retina but in no other ocular structure. No endozoites and no extra-cystic antigens were detected by this technique within any of the eyes examined. The possible implications of these findings in relation to the pathogenesis of toxoplasmic retinochoroiditis are discussed.

Animals↗
PubMed2001

Effect of interfering substances on current response of recombinant peroxidase and glucose oxidase-recombinant peroxidase modified graphite electrodes.

Graphite electrodes have been modified with different forms of horseradish peroxidase (HRP). These included native HRP, wild-type recombinant HRP, and two single-point recombinant HRP mutants, N70V and N70D. The mediator-less response of these electrodes to H2O2 was studied indicating that electrodes modified with recombinant HRP forms are more stable than those modified with native HRP. Various interfering compounds were investigated for their effect on the current response to H2O2. It was found that interferences such as acetaminophen and dopamine affected the response by mediating the electron transfer (ET) between graphite and peroxidases. The mediating behaviour manifested itself as an increased current of the electrode to H2O2. The interfering effect was less pronounced for the electrodes modified with recombinant HRPs possessing better electronic coupling with the graphite surface. The interfering behaviour of acetaminophen on the response for glucose with the bienzyme electrode containing co-immobilised glucose oxidase and HRP was mainly ascribed to mediation of ET between graphite and HRP. It was experimentally proven that a high efficiency of direct ET between graphite and recombinant HRP substantially reduces the interfering effect of acetaminophen.

Journal Article↗
PubMed1990

Mineralization of C-Ring-Labeled Synthetic Lignin Correlates with the Production of Lignin Peroxidase, not of Manganese Peroxidase or Laccase.

Recently, Mn(II) has been shown to induce manganese peroxidases (MnPs) and repress lignin peroxidases (LiPs) in defined liquid cultures of several white rot organisms. The present work shows that laccase is also regulated by Mn(II). We therefore used Mn(II) to regulate production of LiP, MnP, and laccase activities while determining the effects of Mn(II) on mineralization of ring-labeled synthetic lignin. At a low Mn(II) level, Phanerochaete chrysosporium and Phlebia brevispora produced relatively high titers of LiPs but only low titers of MnPs. At a high Mn(II) level, MnP titers increased 12- to 20-fold, but LiPs were not detected in crude broths. P. brevispora formed much less LiP than P. chrysosporium, but it also produced laccase activity that increased more than sevenfold at the high Mn(II) level. The rates of synthetic lignin mineralization by these organisms were similar and were almost seven times higher at low than at high Mn(II). Increased synthetic lignin mineralization therefore correlated with increased LiP, not with increased MnP or laccase activities.

Journal Article↗
PubMed1995

Lignin Peroxidases, Manganese Peroxidases, and Other Ligninolytic Enzymes Produced by Phlebia radiata during Solid-State Fermentation of Wheat Straw.

The white rot fungus Phlebia radiata 79 (ATCC 64658) produces lignin peroxidase (LiP), manganese peroxidase (MnP), glyoxal oxidase (GLOX), and laccase in the commonly used glucose low-nitrogen liquid medium. However, the enzymes which this fungus utilizes for selective removal of lignin during degradation of different lignocellulosic substrates have not been studied before. Multiple forms of LiP, MnP, GLOX, and laccase were purified from P. radiata culture extracts obtained after solid-state fermentation of wheat straw. However, the patterns of extracellular lignin-modifying enzymes studied were different from those of the enzymes usually found in liquid cultures of P. radiata. Three LiP isoforms were purified. The major LiP isoform from solid-state cultivation was LiP2. LiP3, which has usually been described as the major isoenzyme in liquid cultures, was not expressed during straw fermentation. New MnP isoforms have been detected in addition to the previously reported MnPs. GLOX was secreted in rather high amounts simultaneously with LiP during the first 2 weeks of growth. GLOX purified from P. radiata showed multiple forms, with pIs ranging from 4.0 to 4.6 and with a molecular mass of ca. 68 kDa.

Journal Article↗
PubMed1995

Roles of Lignin Peroxidase and Manganese Peroxidase from Phanerochaete chrysosporium in the Decolorization of Olive Mill Wastewaters.

The relative contributions of lignin peroxidase (LiP) and manganese peroxidase (MnP) to the decolorization of olive mill wastewaters (OMW) by Phanerochaete chrysosporium were investigated. A relatively low level (25%) of OMW decolorization was found with P. chrysosporium which was grown in a medium with a high Mn(II) concentration and in which a high level of MnP (0.65 (mu)M) was produced. In contrast, a high degree of OMW decolorization (more than 70%) was observed with P. chrysosporium which was grown in a medium with a low Mn(II) concentration but which resulted in a high level of LiP activity (0.3 (mu)M). In this culture medium, increasing the Mn(II) concentration resulted in decreased levels of OMW decolorization and LiP activity. Decolorization by reconstituted cultures of P. chrysosporium was found to be more enhanced by the addition of isolated LiP than by the addition of isolated MnP. The highest OMW decolorization levels were obtained at low initial chemical oxygen demands combined with high levels of extracellular LiP. These data, plus the positive effect of veratryl alcohol on OMW decolorization and LiP activity, indicate that culture conditions which yield high levels of LiP activity lead to high levels of OMW decolorization.

Journal Article↗
PubMed1978

Neutralization tests for dengue and Japanese encephalitis viruses by the focus reduction method using peroxidase-anti-peroxidase staining.

Neutralization tests were made on 4 types of dengue (DEN) virus and Japanese encephalitis (JE) virus by incubation of serially diluted antisera and constant amounts of the viruses and then focus assay of surviving virus infectivity with peroxidase-anti-peroxidase (PAP) staining. Neutralization reactions were virtually completed in 2 hr on incubation of serum-virus mixtures at 28 C. A straight regression line was obtained on a probit chart by plotting the focus reduction rates at various dilutions of a given serum against the logarithm of the serum dilution used in the test. The slopes of the probit regression lines for the neutralization for DEN types 1 and 3 were similar, but differed somewhat from those for DEN type 2 and type 4. The slope of the line for JE virus was quite different from those for DEN viruses. Using these relations, the fifty percent focus reduction titer (FR50) of neutralizing antibodies of a given serum could be estimated from the focus reduction rates at several dilutions of the test serum when the latter was between 25-75% of the value of the control.

Animals↗
PubMed1979

A modified PAP (peroxidase-anti-peroxidase) staining technique using sera from patients with dengue hemorrhagic fever (DHF): 4 step PAP staining technique.

BHK-21 cells infected with dengue virus type 1 were stained by a newly developed 4 step PAP (peroxidase-anti-peroxidase) technique using sera from patients with dengue hemorrhagic fever as anti-virus antibody. The intensity of staining of the sera was proportional to the hemagglutination inhibition and neutralization titers. With this new technique using sera from patients it should be possible to use the PAP technique of virus infections.

Animals↗
PubMed1984

Platelet crossmatch tests using radiolabelled staphylococcal protein A or peroxidase anti-peroxidase in alloimmunized patients.

Refractoriness to random-donor platelets as a result of alloimmunization remains a major problem in long-term platelet transfusion therapy despite the use of HLA-matched platelets. We have therefore studied the use of two methods for detection of platelet associated IgG as platelet crossmatch tests for the selection of platelet donors. These methods use radiolabelled staphylococcal protein A (125I-SPA) and peroxidase anti-peroxidase (PAP), respectively. One hundred and ten crossmatch tests using 125I-SPA were performed retrospectively in 18 alloimmunized patients. The results indicated that the predictive value of a positive or a negative test was 87%; the sensitivity was 73% and the specificity was 95%. Results with the PAP test were similar. The HLA types were known for 48 donor-recipient pairs. With few exceptions, there was a correlation between the results of the platelet crossmatch tests and the effectiveness of platelet transfusion regardless of the degree of HLA match. These results indicate that platelet crossmatch tests may be valuable even when closely HLA matched donors are not available. A large-scale prospective study is warranted, particularly in highly immunized patients.

Anemia, Aplastic↗
PubMed1996

Cloning of the murine eosinophil peroxidase gene (mEPO): characterization of a conserved subgroup of mammalian hematopoietic peroxidases.

The mouse eosinophil peroxidase (mEPO) gene was cloned by screening a random-primed bone marrow cDNA library at reduced criteria using a hEPO cDNA. An mEPO cDNA was subsequently used to isolate the mEPO gene from a lambda-genomic library. The mEPO gene displays a high degree of conservation with its human homologue: the transcription units are approximately the same size, conserve the relative size and position of the 12 exons associated with each gene, and at a nucleotide level the mouse and human EPO genes are 86% identical in the protein coding regions and 66% identical in the 3'-untranslated trailer regions. This strong conservation extends to the encoded proteins which show approximately 90% amino acid identity. Expression of the mEPO gene is restricted to tissues containing eosinophil progenitor cells (e.g., bone marrow and spleen), a pattern similar to the expression of another murine eosinophil granule protein, major basic protein.

Amino Acid Sequence↗
PubMed1981

A light and electron microscopic study of the intraneuronal transport of horseradish peroxidase and wheat germ agglutinin-peroxidase conjugates in the rat visual system.

The ability of horseradish peroxidase (HRP) and the lectin wheat germ agglutinin (WGA) covalently conjugated with HRP to label retrogradely dorsal lateral geniculate nucleus (dLGN) neurons, subsequent to injections of either marker into rat striate cortex, was assessed by counting labelled neurons in the dLGN. Rats injected with either marker in concentrations ranging from 0.1 to 100 micrograms/microliter of HRP either free or coupled to WGA were perfused 24 h later and their brains incubated using the chromagen tetramethyl benzidine. At high concentrations (2-100 micrograms/microliters), comparable numbers of labelled neurons were observed in the dLGN but at low concentrations (0.1-1.0 micrograms/ microliters), WGA-HRP labelled 2-5 times more dLGN neurons than did unconjugated HRP. The sugar N-acetylglucosamine, and free WGA added in excess to WGA-HRP, abolished the retrograde labelling of dLGN neurons. In additional rats, which received striate cortex injections of 100 micrograms/microliters of either free HRP or HRP coupled to WGA, the injection site was studied with electron microscopy after survivals of 30 min to 24 h. Similar organelles in neuronal perikarya, dendrites and axons were labelled by both markers, with the exception that only rats injected with WGA-HRP had labelled GERL in some of their neurons in striate cortex. It was concluded from these studies that: (1) WGA-HRP is a more sensitive retrograde marker than free HRP at low concentrations in the rat visual system; (2) WGA-HRP binds specifically to moieties with terminal N-acetylglucosamine; and (3) WGA-HRP, but not free HRP, is localized to neuronal GERL of striate cortex subsequent to endocytosis.

Acetylglucosamine↗
PubMed1986

Peroxidase activity at nodes of ranvier in lumbosacral ventral spinal roots and in the PNS-CNS transitional region after intramuscular administration of horseradish peroxidase.

The axoplasm of nodes of Ranvier in feline lumbosacral ventral spinal roots was analysed by light and electron microscopy 18-168 h after the injection of horseradish peroxidase (HRP) into the medial gastrocnemius muscle. Three main HRP distribution patterns were distinguished at PNS nodes (bordered by Schwann cells only) of large fibres transporting HRP. The type A pattern, characterized by a distal accumulation of HRP-positive bodies and a proximal system of vesiculotubular membrane profiles. The incidence of this type of node was highest at relatively short survival times. The type B pattern, which appeared somewhat later, resembled the type A node with the addition of a disc-like, proximal accumulation of HRP activity. The type C pattern which contained scattered HRP-positive bodies and delicate strands of membraneous profiles, dominated 72 h after injection. The number of HRP-positive PNS-CNS borderline nodes (bordered by both Schwann cells and glial cells) was less than 5% of the corresponding value in the same fibres of the ventral root proper. A highly segregated state of the axoplasm of PNS-CNS borderline nodes was noted only in two cases. The observations indicate a functional difference between nodal axoplasm at the PNS-CNS borderline and nodal axoplasm in the PNS part of the alpha motor neuron.

Animals↗
PubMed1985

Peroxidase activity at nodes of Ranvier in some commonly used laboratory animals after intramuscular administration of horseradish peroxidase.

During retrograde transport of intramuscularly administrated horseradish peroxidase (HRP) nodal axon segments of rabbit, rat, and mouse peripheral nerve fibers became HRP-positive and showed a striking proximodistal segregation of certain axoplasmic organelles. HRP-positive bodies and HRP-negative vesiculotubular membrane profiles were seen just distal and proximal to the nodal midlevel, respectively. This appearance was similar to that found earlier in HRP-transporting feline muscle nerve fibers. Some mechanisms that might explain the segregated appearance are briefly discussed.

Animals↗
PubMed1988

Activation of carcinogens by peroxidase. Horseradish peroxidase-mediated formation of benzenediazonium ion from a non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene (Sudan I) and its binding to DNA.

Horseradish peroxidase in the presence of hydrogen peroxide (HRP/H2O2) oxidizes a carcinogenic non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene (Sudan I) to the ultimate carcinogen, which binds to calf thymus DNA. The principal product of Sudan I oxidation by the HRP/H2O2 system is the benzenediazonium ion. Minor products are hydroxy derivatives of Sudan I, in which the aromatic rings are hydroxylated. The principal oxidative product (the benzenediazonium ion) is responsible for the carcinogenicity of Sudan I, because this ion, formed from this azo dye, binds to DNA.

Animals↗
PubMed1983

Zero-field splitting of Fe3+ in horseradish peroxidase and of Fe4+ in horseradish peroxidase compound I from electron spin relaxation data.

From the temperature dependence of the Orbach relaxation rate of the paramagnetic center in horseradish peroxidase (HRP), we deduce an excited-state energy of 40.9 +/- 1.1 K. Similar studies on the broad EPR signal of HRP compound I indicate a much weaker Orbach relaxation process involving an excited state at 36.8 +/- 2.5 K. The strength of the Orbach process in HRP-I is weaker than one would normally estimate by 2-4 orders of magnitude. This fact lends support to the model of HRP-I involving a spin 1/2 free radical coupled to a spin 1 Fe4+ heme iron via a weak exchange interaction. Such a system should exhibit an Orbach relaxation process involving delta E, the excited state of the Fe4+ ion, but reduced in strength by (Jyy/delta E)2, where Jyy is related to the strength of the exchange interaction between the two spin systems.

Electron Spin Resonance Spectroscopy↗
PubMed2001

Crystal structure of Nitrosomonas europaea cytochrome c peroxidase and the structural basis for ligand switching in bacterial di-heme peroxidases.

The crystal structure of the fully oxidized di-heme peroxidase from Nitrosomonas europaea has been solved to a resolution of 1.80 A and compared to the closely related enzyme from Pseudomonas aeruginosa. Both enzymes catalyze the peroxide-dependent oxidation of a protein electron donor such as cytochrome c. Electrons enter the enzyme through the high-potential heme followed by electron transfer to the low-potential heme, the site of peroxide activation. Both enzymes form homodimers, each of which folds into two distinct heme domains. Each heme is held in place by thioether bonds between the heme vinyl groups and Cys residues. The high-potential heme in both enzymes has Met and His as axial heme ligands. In the Pseudomonas enzyme, the low-potential heme has two His residues as axial heme ligands [Fulop et al. (1995) Structure 3, 1225-1233]. Since the site of reaction with peroxide is the low-potential heme, then one His ligand must first dissociate. In sharp contrast, the low-potential heme in the Nitrosomonas enzyme already is in the "activated" state with only one His ligand and an open distal axial ligation position available for reaction with peroxide. A comparison between the two enzymes illustrates the range of conformational changes required to activate the Pseudomonas enzyme. This change involves a large motion of a loop containing the dissociable His ligand from the heme pocket to the molecular surface where it forms part of the dimer interface. Since the Nitrosomonas enzyme is in the active state, the structure provides some insights on residues involved in peroxide activation. Most importantly, a Glu residue situated near the peroxide binding site could possibly serve as an acid-base catalytic group required for cleavage of the peroxide O--O bond.

Amino Acid Sequence↗