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PubMed1982

Mild and efficient conjugation of rabbit Fab' and horseradish peroxidase using a maleimide compound and its use for enzyme immunoassay.

A mild and efficient procedure for conjugating rabbit Fab' and horseradish peroxidase using a maleimide compound was developed. The enzyme was treated with N-hydroxysuccinimide ester of N-(4-carboxycyclohexylmethyl) maleimide to introduce maleimide groups. Then, the maleimide-enzyme was allowed to react with thiol groups of Fab', and the conjugate formed was separated from unreacted components by gel filtration with Ultrogel AcA 44. In the peak fraction of the separated conjugate, 98% of peroxidase was associated with Fab' and 90% of antibodies was associated with peroxidase. The recoveries in the conjugate of peroxidase and Fab' incubated for conjugation were 65-74%. The conjugate formed appeared to be largely monomeric. Both the enzyme activity and antigen-binding activity of Fab' were fairly well preserved in the conjugate. The cross-link formed was stable at 4 degrees C at least 6 months. Use of the conjugates obtained by this method gave greater sensitivity in sandwich enzyme immunoassay for human ferritin and human thyroid-stimulating hormone than conjugates prepared by the periodate method. The conjugation using N-hydroxysuccinimide ester of m-maleimidobenzoic acid provided a similar monomeric preparation but was less efficient.

Animals↗
PubMed1984

Comparison of beta-D-galactosidase from Escherichia coli and horseradish peroxidase as labels of anti-human ferritin Fab' by sandwich enzyme immunoassay technique.

beta-D-Galactosidase from Escherichia coli and horseradish peroxidase were compared as labels of anti-human ferritin Fab' by sandwich enzyme immunoassay technique using fluorogenic substrates for enzyme assay. The anti-human ferritin Fab'-peroxidase conjugates gave lower nonspecific bindings and higher specific bindings than the corresponding Fab'-beta-D-galactosidase conjugates. As a result, the former provided more sensitive dose response curves for human ferritin than the latter. However, the peroxidase conjugates were required in a larger quantity, since peroxidase assay was much less sensitive than beta-D-galactosidase assay.

Antibodies↗
PubMed1994

Regulation of pea cytosolic ascorbate peroxidase and other antioxidant enzymes during the progression of drought stress and following recovery from drought.

The molecular mechanism underlying the regulation of the expression of Apxl, the gene encoding cytosolic ascorbate peroxidase, as well as other antioxidant enzymes, was studied during the progression of drought stress and following recovery from drought. Increase in steady-state transcript levels of the cytosolic isozymes of ascorbate peroxidase and Cu/Zn-superoxide dismutase paralleled the increase in stomatal resistance during drought stress, but was even more dramatically enhanced following recovery from drought. Cytosolic Cu/Zn-superoxide dismutase and ascorbate peroxidase and chloroplastic Cu/Zn-superoxide dismutase protein and activity increased during drought stress and following recovery. In contrast, catalase activity increased during drought stress but returned to normal levels following recovery. During recovery from drought stress, cytosolic ascorbate peroxidase expression was regulated post-transcriptionally at the level of protein synthesis. The transcription rate of the Apxl gene, as determined by nuclear run-on assay, increased during drought stress and at 10 h following rewatering.

Ascorbate Peroxidases↗
PubMed1995

Effects of delmopinol on antimicrobial peroxidase systems and lysozyme in vitro and in human whole saliva.

Delmopinol is a new surface-active agent which can reduce plaque formation and gingivitis. This study was aimed to analyze whether delmopinol (0.0032-0.65 mM) interferes with the activity of two surface-active oral antimicrobial enzymes, salivary peroxidase and lysozyme. In addition to human whole saliva (pH 5.0 and 6.0), the experiments were done in 0.1 M phosphate buffer (pH 6.0) with purified lactoperoxidase (LPO) and myeloperoxidase (MPO). LPO and MPO were significantly inhibited in buffer by delmopinol concentrations > 6.5 mM and > or = 3.2 mM, respectively. No such inhibition was found for total peroxidase activity in mixed saliva. In vitro, delmopinol was found to desorb surface-bound peroxidases in an active form to the liquid phase. In further analyses, the possible effect of delmopinol on peroxidase-generated hypothiocyanite (HOSCN/OSCN-) was studied in saliva and buffer. No effect was found in buffer, but salivary HOSCN/OSCN- declined significantly with 6.5 mM delmopinol. This was obviously due to an enhanced decay of hypothiocyanite, rather than its reduced rate of formation. No delmopinol-related inhibition of lysozyme occurred in saliva or buffer. The results suggest that high concentration (6.4 mM -0.2%) of delmopinol may lower the concentrations of antimicrobial HOSCN/OSCN- in saliva but has no effect on human lysozyme.

Anti-Infective Agents↗
PubMed2004

The investigation of glutathione peroxidase, lactoferrin, myeloperoxidase and interleukin-1beta in gingival crevicular fluid: implications for oxidative stress in human periodontal diseases.

BACKGROUND: Human periodontal diseases are inflammatory disorders that are the result of complex interactions between periodontopathogens and the host's immune response. Two important and interrelated factors are involved in the pathophysiological progression of periodontal diseases, i.e. the activation of immune system and the production of oxygen radicals and their related metabolites. Increased production of oxygen radicals may contribute to oxidative stress, which is reported to be involved in many diseases, including periodontal diseases. OBJECTIVES: The objective of this study was to investigate glutathione peroxidase, lactoferrin and myeloperoxidase, which play an essential role in free radical production and defenses, and the proinflammatory cytokine interleukin-1beta (IL-1beta), which is important in the regulation of immunological and inflammatory reactions in human periodontal diseases. METHODS: Gingival crevicular fluid (GCF) samples were collected from 27 subjects, 19 periodontitis patients and eight healthy controls, ranging in ages from 24 to 62 years. Clinical parameters were recorded. GCF glutathione peroxidase, lactoferrin, myeloperoxidase and IL-1beta were analyzed by enzyme-linked immunosorbent assays (ELISA). RESULTS: The periodontitis sites exhibited significantly greater total amount of glutathione peroxidase, lactoferrin, myeloperoxidase and IL-1beta than healthy sites. Total amount of glutathione peroxidase, lactoferrin, myeloperoxidase and IL-1beta was positively correlated with plaque index, gingival index, probing depth and probing attachment level (p < 0.05). CONCLUSION: The imbalance between the levels of myeloperoxidase/IL-1beta and glutathione peroxidase/lactoferrin could result in tissue damage of reactive oxygen species (ROS) in periodontitis which is initiated and perpetuated by the chronic insults of periodontopathogens.

Adult↗
PubMed1994

Correlation of phospholipid hydroperoxide glutathione peroxidase activity to the sensitivity of rat retinas to photic injury.

We hypothesize that the differential susceptibility to photic injury among different strains of rat retinas may depend on the levels of phospholipid hydroperoxide glutathione peroxidase (PHGPX) activity, one of the endogenous antioxidant enzymes in the retina. The retinas of four inbred strains of albino rat (Fischer, Wistar, Buffalo and Lewis) were analyzed for glutathione peroxidase activity using H2O2, cumene hydroperoxide, and phospholipid hydroperoxide as assay substrates. In all four strains of rat, PHGPX was observed only in the high salt extract of the retina, while peroxidases determined by H2O2 or cumene hydroperoxide were observed mainly in the low salt extract. PHGPX was highest (66.7 mU/mg) in the most light-resistant Fischer strain and lowest in the most light-sensitive Lewis strain (31.9 mU/mg), while the activity levels in the moderately light-sensitive Buffalo and Wistar strains were 46.6 and 38.5 mU/mg, respectively. In contrast, there was no significant difference in peroxidases determined by H2O2 or cumene hydroperoxide among the four strains. These observations suggested that, in rat retina, the membrane-associated PHGPX may have an important role in the defense against light-induced free radical damage.

Animals↗
PubMed1976

The alteration of superoxide dismutase, catalase, glutathione peroxidase, and NAD(P)H cytochrome c reductase in guinea pig polymorphonuclear leukocytes and alveolar macrophages during hyperoxia.

Superoxide dismutase, catalase, glutathione peroxidase and NAD(P)H cytochrome c reductase were quantitated in polymorphonuclear leukocytes (PMN) and alveolar macrophages (AM) obtained from guinea pigs exposed up to 90 h to 85% oxygen. PMN and AM were sonicated and separated into a 16,000-g pellet, a 100,000-g pellet, and a 100,00-g supernate. Superoxide dismutase activity increased in both cells within 18 h, persisted for 66 h and decreased by 90 h. The highest rate of increase was in the 100,000-g pellet containing 3.4% of total enzyme activity in PMN but 28% in AM. The enzyme induction in PMN and AM was partially inhibited by daily intracardiac injections of 50 mg/kg actinomycin D. During oxygen exposure, catalase activity in PMN and AM decreased to 60% of its original activity, and gluthathione peroxidase was reduced in PMN to 60% and in AM to 20% of control values. Although NAD(P)H cytochrome c reductase decreased to 50% in PMN, no change was noted in AM. Upon exposure to superoxide anion, purified catalase, the glutathione peroxidase of the 100,000-g supernate, NADH, and NADPH cytochrome c reductases of the 16,000-g pellet decreased to 66+/-5%, 72+/-4%, 52+/-8%, and 40+/-9%, respectively, of their original activity. This inactivation was prevented by 0.1 mg superoxide dismutase. These in vitro observations could explain the decreased catalase and glutathione peroxidase activity demonstrated in vivo that may lead to an intracellular accumulation of hydrogen peroxide. Increased hydrogen peroxide concentrations have been found to inactivate superoxide dismutase thus impairing the first defense mechanism against superoxide anion.

Animals↗
PubMedDate not supplied

Effect of propranolol on peroxidase in tracheal epithelial cells.

Propranolol (beta-blocker) was administered to five guinea pigs in doses of 6 mg/day for ten days; five uninjected animals were used as controls. The first or second tracheal ring was cut in round slices. The number of overall epithelial cells facing the airway and the epithelial cells with peroxidase were counted. The mean percentage of peroxidase-positive cells to total epithelial cells was 49% in the control and 11% in animals after the administration of propranolol. This result apparently meant that the peroxidase activity was decreased by the administration of propranolol. The relationship between allergic diseases and the synthesis of peroxidase is discussed.

Animals↗
PubMed1987

Comparison of horseradish peroxidase and alkaline phosphatase-labelled antibodies in enzyme immunoassays.

The periodate method was found to be most effective for preparing horseradish peroxidase-sheep anti-human and horseradish peroxidase-donkey anti-mouse immunoglobulin (IgG) conjugates. The conjugates were improved by carrying out the oxidation of the enzyme at low pH. Anti-human and anti-mouse IgG-peroxidase conjugates (0.5 mg/mL IgG and 0.7 mg/mL IgG, respectively) were used at 1:15,000 and 1:8000 dilutions, respectively, in a sandwich ELISA to detect human and mouse IgG in buffer or in a growth medium containing 20% foetal calf serum. Using the peroxidase conjugates, it was possible to detect human and mouse IgG at concentrations as low as 1 ng/mL. The glutaraldehyde method was found to be much more effective than the periodate method for conjugating alkaline phosphatase to the antibodies. The optimum dilutions for anti/human and anti-mouse IgG-alkaline phosphatase conjugates (0.18 mg/mL IgG and 0.3 mg/mL IgG, respectively) in ELISA were 1:500 and 1:1000, respectively. The detection limit with alkaline phosphatase conjugates was 7 ng/ml for human IgG and 4 ng/ml for mouse IgG.

Alkaline Phosphatase↗
PubMed1976

Arterial hypotension induced by horseradish peroxidase in various rat strains.

The influence of various commercial preparations of horseradish peroxidase upon the arterial pressure has been investigated using direct intra-arterial pressure recordings in Nembutal anesthetized rats of different strains. A marked hypotension was noted in Wistar and Sprague-Dawley rats when sufficiently high doses (5-10 mg/100 g body weight) were injected intravenously. This effect was observed with both highly purified (Sigma type VI, Boehringer Reinheitsgrad I) as well as less pure preparations (Sigma type II, Boehringer Reinheitsgrad II). Prior injection of promethazin, an antihistamine, prevented the drop in arterial pressure. Wistar/Furth rats appeared almost resistant to the hypotensive effect of Sigma preparations but developed moderate to marked hypotension with both types of Boehringer horseradish peroxidase. When instead of Nembutal, ether anesthesia was used only a transient mild hypotension developed and the animals recovered within 7-10 min. No effect was noted in Syrian hamsters receiving injections with the same doses of horseradish peroxidase. Electrophoresis revealed marked variations in the isozyme composition of different horseradish peroxidase preparations. Since the exact nature of the hypotensive agent remains unknown, it is suggested that the arterial pressure be monitored before extensive systematic application of this tracer in vascular permeability studies in rats.

Animals↗
PubMed1978

Use of horseradish peroxidase to block nonspecific enzyme uptake in immunoperoxidase microscopy.

Intrinsic tissue peroxidase activity can be more or less successfully destroyed by methanol-H2O2 treatment. It has been found, however, in our laboratory that horseradish peroxidase (HRP) coupled to antibody will bind to some tissue components on a nonspecific basis and remain to take part in the histochemical stain. This contributes considerably to the background. This difficulty can be largely overcome if the tissues are pretreated with a solution of horseradish peroxidase which binds with nonspecific tissue sites. The adsorbed enzyme, along with the intrinsic peroxidase, can then be successfully inactivated by methanol-H2O2 treatment. By this method of blocking, there is considerable reduction in background staining.

Histocytochemistry↗
PubMed1980

Factors affecting the sensitivity and specificity of the cytochemical reaction for the anti-horseradish peroxidase antibody in lymph tissue sections.

Factors which increase the sensitivity and specificity of the cytochemical reaction for the antibody to horseradish peroxidase (HRP) in precursors of plasma cells and in lymphocytes were studied in sections of popliteal lymph nodes of rats. The lymph nodes were removed 3-5 days after a secondary injection of HRP into the footpads and were fixed for 5 hr in a 4% cold formaldehyde solution (Straus W: Histochemistry 53:273, 1977). Brief postfixation of the frozen sections with cold acetone improved the retention of the antigen at the sites of the antibody in the precursor cells, and it improved the quality of fixation without appreciably weakening the antigen-binding capacity of the antibody. The cytochemical reaction for the anti-HRP antibody was intensified by staining with diaminobenzidine (DAB) and H2O2 at pH 5-6, or by staining at pH 7.4 in the presence of imidazole. Imidazole partially inhibited endogenous peroxidase activity. Pretreatment with phenylhydrazine prevented nonspecific background adsorption of HRP. Phenylhydrazine had the additional advantage of inhibiting most of the endogenous peroxidase activity (Straus W: J Histochem Cytochem 20:949, 1972). The intensity of the antibody reaction in the proplasma cells developing in the medullary cords varied greatly depending on the stage of maturation from lymphocytes and blast cells. Many lymphocytes in the cortex of the lymph node showed a strong perinuclear antibody reaction when the tissue sections were postfixed with cold acetone, and the peroxidase complexed to the antibody was visualized by staining with DAB and H2O2 at pH 5-6. The antibody reaction also occurred at the surgace of many lymphocytes when the tissue sections, postfixed with cold acetone, were stained with DAB and H2O2 at pH 7.4 in the presence of imidazole. Other lymphocytes showed a strong surface, perinuclear, and cytoplasmic antibody reaction after staining at pH 5-6 as well as after staining at pH 7.4, while yet other lymphocytes remained unstained.

Animals↗
PubMed1984

Peroxidase activity in human cutaneous mast cells: an ultrastructural demonstration.

An intense and reproducible peroxidase staining in the cutaneous mast cells of two patients with systemic mast cell disease and urticaria pigmentosa is demonstrated at the ultrastructural level. This enzyme activity was demonstrated by use of a cytochemical technique employing 3,3'- diaminobenzicine (DAB) as an oxidizable substrate, after fixation by a tannic acid-aldehyde mixture. Enzyme activity was localized in the perinuclear cisterna and strands of endoplasmic reticulum. Granules appeared unreactive. This peroxidase activity appears sensitive to fixation by aldehydes; it is inhibited by 3-amino-1,2,4-triazole (AMT) and by lack of H2O2 or DAB in the incubation medium. These characteristics are fundamentally different from the peroxidase activity of basophils, and the demonstration of this enzyme is therefore not a further argument for a common ontogenetic origin of both cells. On the other hand, the cytochemical characteristics of this enzyme are very similar to those of platelet peroxidase (P-PO), which has been connected to the synthesis by platelets of prostaglandins. Since the mast cell is known to generate prostaglandins, the relationship between the enzyme described and prostaglandin synthesis by mast cells is discussed.

Cell Nucleus↗
PubMed1986

The development of the resident pattern of endogenous peroxidatic activity in mouse peritoneal macrophages coincides with the expression of the differentiation antigen F4/80. A combined method for immunoperoxidase labeling and endogenous peroxidase cytochemistry.

In the mouse the maturation of mononuclear phagocytes was followed by comparing the ultrastructural pattern of endogenous peroxidatic activity (PA) at different time points during an acute peritonitis induced with newborn calf serum (NCS). Exudate macrophages demonstrate PA only in lysosomes, whereas resident macrophages have reaction product in the nuclear envelope (NE) and rough endoplasmic reticulum (RER). Transitional cells called "exudate-resident" macrophages have PA in the NE, RER, and some virginal lysosomes. In addition, peroxidase-negative macrophages were also present. A monoclonal antibody, F4/80, that specifically recognizes a mouse macrophage differentiation antigen (Austyn and Gordon, 1981) was used in this study. To compare the indirect immunoperoxidase labeling of this antigen and the endogenous peroxidase cytochemistry on the cellular level, a combined method was developed. Finally, the method was applied to the peritoneal cells at different time points after intraperitoneal injection of NCS in mice. The relative numbers of cells demonstrating the different patterns of endogenous PA and the proportions of each subpopulation expressing F4/80 antigen were estimated. It appeared that the expression of the antigen F4/80 coincides with the development of the resident pattern of PA. It is therefore concluded that the macrophages with the resident pattern of endogenous peroxidase are derived from monocyte-like exudate macrophages. In addition, the results indicate that both exudate-resident macrophages and at least a part of the peroxidase-negative macrophages are transitional forms.

Animals↗
PubMed2003

Thiol-dependent peroxidases care little about homology-based assignments of function.

Thiol-dependent peroxidase systems are reviewed with special emphasis on their potential use as drug targets. The basic catalytic mechanism of the two major thiol-peroxidase families, the glutathione peroxidases and the peroxiredoxins, are reasonably well understood. Sequence-based predictions of substrate specificities are still unsatisfactory. GPx-type enzymes are not generally specific for GSH but may specifically react with CXXC motifs as present in thioredoxins or tryparedoxins. Inversely, the peroxiredoxin family that was believed to be specific for CXXC-type proteins, also comprises glutathione peroxidases. Since structure-based predictions of function are also limited by small data bases, the increasing number of sequences emerging from genome projects require enzymatic characterization and genetic proof of relevance before they can be classified as drug targets.

Animals↗
PubMed1976

Thyroid iodine organification defects: a case with lack of thyroglobulin iodination and a case without any peroxidase activity.

Two patients (G2, G3) with iodine organification defect were studied. The first patient (G2), a 25-year-old women with no clinical hypothyroidism, had had her goiter for 10 years; 62% of the thyroidal iodine was released by perchlorate indicating iodine organification defect. The thyroid tissue obtained at thyroidectomy contained a normal concentration of thyroid peroxidase (I2 formation from I-) when tested after solubilization of the enzyme by trypsin and digitonin treatment of the particulate material. 1. The enzymatic activity (G2-TPO) behaved on DEAE cellulose chromatography very differently from those of hog (P-TPO) or another human goiter peroxidase (G1-TPO) (Pommier, et al., J Clin Endocrinol Metab 39: 69, 1974): the molarity of elution was 2M NaCl instead of 0.15 mM. 2. Both P-TPO and G2-TPO catalyzed iodide peroxidation (I- leads to I2) but the Km (iodide) value for G2-TPO was much lower (2.3 x 10(-2) M) when compared with that of P-TPO (3.7 x 10(-3) M) or G1-TPO (3.5 x 10(-3) M). In addition, the optimum pH for this reaction differed markedly (pH 6.1 instead of 7.9). 3. G2-TPO was poorly efficient in catalyzing the oxidation of gaiacol to tetragaiacol. 4. G2-TPO was unable to perform the iodination of non-iodinated goiter thyroglobulin whatever the pH and the iodide concentration. 5. Thyroglobulin from this goiter (G2) was almost not iodinated (0.0014%), i.e., 0.07 atoms iodine/mole thyroglobulin), and its total content in the gland was very low (0.3-4 g/1000 g wet tissue instead of 25 g). A clear discrepancy was thus shown between the euthyroid state of this patient and the total lack of iodinating activity of the isolated peroxidase. The second patient (G3), a 17-year-old man with clinical hypothyroidism, had had his goiter for 5 years. 100% of the thyroidal iodine was released by perchlorate indicating a complete iodine organification defect. The thyroid tissue obtained at thyroidectomy contained no peroxidase activity when tested before and after treatment of the particulate material by trypsin and digitonin and even in the presence of hematin. Thyroglobulin from this goiter, which was almost non-iodinated (0.0014%), was present in normal amounts in the gland (congruent to 25 g/1000 g).

Adolescent↗
PubMed1985

In vitro effect of estrogens on the peroxidase activity of human endometrium.

The effect of estrogen on the induction of human endometrial peroxidase was studied in vitro. When 17 beta-estradiol was added to the incubation medium, endometrial peroxidase activity was markedly increased, and the highest enzymatic activities were reached at about 12 h of incubation. The ability of estrogen and related compounds to increase peroxidase activity at a concentration of 10(-7) M was 17 beta-estradiol greater than estrone greater than 17 alpha-ethynylestradiol greater than estriol = diethylstilbestrol. Mestranol, progesterone, and testosterone had almost no activity. The induction of peroxidase by 17 beta-estradiol was inhibited by actinomycin D or cycloheximide. This method may be useful for determining the direct estrogenic effect of compounds in human endometrium.

Cycloheximide↗