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)

Two fractions of gastric mucosal membranes obtained by Ficoll-sucrose density gradient centrifugation were studied by a variety of techniques to localize the polypeptides. Gel electrophoresis showed the presence of five major polypeptides and several minor ones. Only one of these, 82,000 daltons, was available for iodination in the intact tissue. The two membrane fractions differed in their accessibility to peroxidase. The denser fraction showed two major defined iodination peaks at 82,000 and 102,000 daltons. Freeze-thawing and iodinating with 131-I produced additional labeling of peaks as well as relabeling the 82,000-dalton component, showing it was accessible from both sides of the membrane. The two major components were also sensitive to cross-linking, the 102,000 polypeptide being especially sensitive to --SH oxidation. Proteolysis with trypsin removed both components in the denser membrane fraction, in addition to inhibiting the K+-ATPase and K+-p-nitrophenylphosphatase of that fraction. Phosphorylation with [gamma-32-P]ATP labeled the 102,000-dalton component and K+, HCO3- minus and p-nitrophenylphosphate reduced the level of labeling. Hence the 102,000 region contains a subunit of the ATPase, is readily iodinated in inside-out vesicles, and is the most available for interpeptide S--S cross-linking.
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PMID:Characterization of gastric mucosal membranes. VIII. The localization of peptides by iodination and phosphorylation. 16 6

Compounds were studied that inhibit the oxidative degradation of human serum albumin by peroxidase and the enzyme model, iron hydroxide. Differences between the two oxidants gave clues for the mechanism of inhibition. The inhibitors studied were inorganic anions, phosphate, sulfate, carbonate and molybdate; organic anions, decanoate and glycocholate; and the nonionic species, glycogen. Such inhibitors might be considered as adjuvants in senescence: by decreasing the rate of enzymic oxidation of essential body proteins, they would, in the course of aging, reduce some of the physiological changes occurring as a result of accumulation of degraded protein.
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PMID:Inhibitors of oxidative degradation of protein: gerontological implications. 44 Feb 99

Acute lead encephalopathy was induced in adult guinea pigs with daily oral doses of lead carbonate. Cerebral capillaries were examined by electron microscopy, and the blood-brain barrier (B-BB) evaluated with Evans blue and horseradish peroxidase. Brain lead levels were also determined during the developing encephalopathy. There was no cerebral capillary alteration or demonstrable B-BB dysfunction. Brain lead concentrations increased over the 5-day period. The encephalopathy in the absence of any vascular alteration suggests that lead can produce a primary toxic effect at the neuronal level.
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PMID:Acute lead encephalopathy in the guinea pig. 121 Nov 9

Acute lead encephalopathy was induced in adult guinea pigs by administering daily oral doses of lead carbonate. During the development of the encephalopathy, the structural and functional integrity of the blood-brain barrier was evaluated with electron microscopy and tracer probes. Blood, cerebral gray matter, liver, and kidney were analyzed for lead, calcium, and magnesium content. The animals regularly developed an encephalopathy after four doses of lead. There were no discernible pathomorphologic alterations in the cerebral capillaries or perivascular glial sheaths. Furthermore, no evidence of blood-brain barrier dysfunction was demonstrated with Evans blue-albumin complex or horseradish peroxidase. Blood-brain barrier permeability to radiolead was not increased in the intoxicated animals. During the development of the encephalopathy there was a progressive rise in the lead concentration in all tissues. Concurrently, there was a significant rise in brain calcium. These results suggest that the encephalopathic effects of lead may be mediated directly at the neuronal level.
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PMID:Blood-brain barrier dysfunction in acute lead encephalopathy: a reappraisal. 122 64

Intercalated cells (ICs) in the collecting duct and the connecting tubule (CNT) are involved in H+ secretion and HCO3- reabsorption. H+ secretion is mediated by an H(+)-adenosinetriphosphatase in the apical plasma membrane, whereas a band 3-like Cl(-)-HCO3- exchanger in the basolateral membrane is responsible for HCO3- reabsorption. Recent studies have reported that a band 3-like protein is also present in mitochondria in rabbit ICs. The purpose of this study was to establish the subcellular location of the band 3-like Cl(-)-HCO3- exchanger in rabbit ICs by electron microscopic immunocytochemistry using a monoclonal antibody, IVF12, against erythrocyte band 3 protein. Rabbit kidneys were preserved by in vivo perfusion with a paraformaldehyde-lysine-periodate solution and processed for immunocytochemistry using a horseradish peroxidase preembedding technique. Band 3 immunostaining was observed on the basolateral plasma membrane of ICs in the outer medullary collecting duct and type A cells in the cortical collecting duct (CCD) and CNT. In addition, distinct staining for band 3 was present in numerous small vesicles and in multivesicular bodies in type A ICs in the CCD and CNT. However, there was no evidence of band 3 immunostaining of mitochondria or of the apical plasma membrane in any cells of the collecting duct. These observations suggest that basolateral Cl(-)-HCO3- exchangers in type A ICs in the rabbit kidney are stored in intracellular vesicles and possibly degraded in the vascular-lysosomal system when these cells are in a resting state. The previously reported band 3 immunolabeling of mitochondria could not be confirmed.
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PMID:Intracellular band 3 immunostaining in type A intercalated cells of rabbit kidney. 137 72

The lactoperoxidase-thiocyanate-hydrogen peroxide (LP) system inhibited the growth of enterotoxigenic Escherichia coli strains responsible for scouring in neonatal and post-weaning piglets. An enzymatic system for hydrogen peroxide generation (glucose oxidase, GO; 0.1 U/ml) and a chemical source (sodium carbonate peroxyhydrate, SCP; 90 mg/l) were used in the LP system to test 19 strains in a 6-h growth assay at 37 degrees C. Only three strains were highly sensitive to the LP/GO system, while all exhibited significant growth inhibition with the LP/SCP system. Hydrogen peroxide alone had less effect than the complete system. The bactericidal activity of the LP/GO system towards a previously resistant strain was greatly increased by increasing the level of glucose oxidase in the system by three- or five-fold.
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PMID:In vitro antibacterial activity of the lactoperoxidase system towards enterotoxigenic strains of Escherichia coli. 145 45

Two populations of intercalated cells, type A and type B, are present in the rat cortical collecting duct (CCD). Type A cells are involved in proton secretion and contain an apical H(+)-adenosinetriphosphatase (ATPase) and a basolateral Cl(-)-HCO3- exchanger. Type B cells are believed to be involved in HCO3- secretion, which is mediated by a Cl(-)-HCO3- exchange process and is Cl- dependent. The aim of this study was to examine the morphological and immunocytochemical response of type B intercalated cells in the rat to increased delivery of Cl- to the CCD. This was accomplished by chronic infusion of a loop diuretic, bumetanide (30 mg.kg body wt-1.day-1), via an osmotic minipump, and simultaneous administration of 0.9% sodium chloride in the drinking water for 6 days. The kidneys were preserved by in vivo perfusion with a periodate-lysine-paraformaldehyde fixative and processed for horseradish peroxidase and protein A gold immunocytochemistry, using rabbit polyclonal antibodies against carbonic anhydrase II, proton ATPase, and band 3 protein. Chronic infusion of bumetanide in combination with a high salt intake was associated with significant changes in the intercalated cells. Type B cells were increased in size and exhibited numerous apical microvilli, increased basolateral membrane area, and marked cytoplasmic and basolateral labeling for H(+)-ATPase. In contrast, type A cells were small and had sparse apical microprojections. H(+)-ATPase immunolabeling was observed primarily over apical tubulovesicles, and there was decreased basolateral immunolabeling for band 3 protein and occasional labeling for band 3 in lysosome-like structures. These observations support the hypothesis that increased delivery of Cl- to the CCD is associated with stimulation of type B intercalated cells to secrete HCO3-. The observations in type A cells are consistent with the cells being in a resting or inactivated state.
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PMID:Immunocytochemical response of type A and type B intercalated cells to increased sodium chloride delivery. 153 33

Components of the lactoperoxidase system were measured during incubation in Isosensitest broth, with enzymatic (glucose oxidase, GO) or chemical (sodium carbonate peroxyhydrate, SCP) means to generate H2O2. When low levels of thiocyanate (SCN-) were used in the GO system, H2O2 was detected and lactoperoxidase (LP) was inactivated when SCN- was depleted. With 10-fold higher SCN-, LP remained active and H2O2 was not detectable. The oxidation product of the LP reaction, most likely hypothiocyanite, was present in low concentrations. When SCP was used for the immediate generation of H2O2 in a system employing low SCN-, half the LP activity was lost within minutes but thereafter it remained stable. Low concentrations of oxidation product were measured and H2O2 was not detected during the course of the experiment. At high SCN- levels, relatively high concentrations of oxidation product were produced immediately, with H2O2 undetectable. The results suggest that the final product of the LP reaction depends on the method of H2O2 generation and the relative proportions of the substrates. Antibacterial activity of the two LPS was tested against an enterotoxigenic strain of Escherichia coli. Both systems showed bactericidal activity within 4 h incubation at 37 degrees C.
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PMID:Studies on the lactoperoxidase system: reaction kinetics and antibacterial activity using two methods for hydrogen peroxide generation. 155 38

The effects of culture media of various compositions on chemiluminescence developing in peroxidase oxidation of luminol with hydrogen peroxide were under study. The findings evidence that the presence of carbonate and bicarbonate ions in the medium results in a two-staged chemiluminescence kinetics and in more intensive chemiluminescence in the peroxidase-luminol-hydrogen peroxide system. This fact has brought the authors to a conclusion that carbonate and bicarbonate-containing media are more effective for the detection of low peroxidase concentrations by the chemiluminescence technique.
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PMID:[Chemiluminescence in the peroxidase oxidation of luminol with hydrogen peroxide in various media]. 172 38

The flow rate and composition of whole saliva were analyzed in 11 women using low dose oral contraceptives in comparison with 11 menstruating women and 10 men. Paraffin-stimulated whole saliva samples were collected Monday, Wednesday and Friday mornings for 1 cycle or 1 month in all subjects, checked for pH and buffer effect (Dentobuff method, Orion Diagnostics, Espoo, Finland, a measure of bicarbonate content) immediately, and frozen for later assay of salivary lysozyme, amylase, peroxidase, thiocyanate, sialic acid, total protein, IgA, IgG, IgM, Mutans streptococci, Lactobacilli, yeasts and aerobic bacteria. The oral contraceptives taken were Marvelon (Organon, Holland) by 4 subjects, Microgynon (Leiras, Finland) by 1, and Trikvilar (Leiras) by 6. The only significant differences between subject groups of cycle phases was a higher salivary buffer effect in oral contraceptive users than that seen in non-users, who resembled male controls. There was a wide individual variation in most values, but less variation in pH and buffer effect. Salivary buffer effect, which is correlated with HCO3-content and salivary flow, is also higher in late pregnancy.
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PMID:Effects of low-dose oral contraceptives on female whole saliva. 183 83


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