Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Partititon of catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase EC 1.11.1.6) and peroxidase (donor:hydrogen-peroxide oxidoreductase EC 1.11.1.7) activities between the red cell membrane and the cytosol were studied under various experimental conditions. A small but significant amount of catalase (1.6%) was retained on human red cell membranes prepared by hemolysing washed red cells with 30 volumes of 10 mM Tris buffer, pH 7.4. Membrane -bound catalase had a relatively higher peroxidase activity than the soluble enzyme fraction. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate of the solubilized membranes demonstrated catalase to be a single band with a molecular weight of 60 000. Membranes prepared from adenosine triphosphate-depleted red cells depicted a two to three-fold increase in catalase activity, as well as an increase in 60 000 molecular weight band on polyacrylamide gel electrophoresis. The extra amount of retained catalase was a less efficient peroxidase than found in fresh membranes. The binding of catalase to ATP-depleted red cell membranes was dependent upon both pH and hemolysing ratio. Red cells incubated at pH 7.1 demonstrated a decrease in bound catalase, as did membranes prepared from red cells hemolysed at 1:100 dilution. beta-Mercaptoethanol decreased the catalase activity in the membranes and increased the odianisidine peroxidase activity without any significant effect on the 60 000-dalton band.
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PMID:Partition of catalase and its peroxidase activities in human red cell membrane: effect of ATP depletion. 2 Sep 53

The turnover of the plasma membrane proteins of hepatoma tissue culture cells was examined by three different methods--loss of polypeptides labeled in situ by lactoperoxidase-catalyzed iodination, loss of membrane polypeptides labeled with amino acid precursors, and loss from the membrane of fucose-labeled polypeptides. In both logarithmically growing and density-inhibited cells the proteins of the membrane are degraded with a half-life of about 100 hours. This is longer than the half-life of total cell protein, 50 to 60 hours, and longer than the doubling time of the cells, about 30 hours. Similar values for the rate of degradation of the membrane proteins were obtained by each of the three techniques. The same fucose-labeled polypeptides are present in the microsomal and the plasma membrane fractions of hepatoma tissue culture cells as analyzed by electrophoresis in dodecyl sulfate-acrylamide gels. But the fucose-labeled polypeptides were lost from the microsomal fraction at a faster rate than from the plasma membrane. Autoradiographic and double labeling techniques using 125I and 131I, or [3H]leucine and [14C]leucine were used to measure the relative rates of degradation of the proteins in the plasma membrane. All of the leucine-labeled polypeptides and the iodinated polypeptides had similar rates of degradation. These results support a model for the biogenesis of the plasma membrane in which the proteins are incorporated and removed in large structural units.
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PMID:Turnover of the plasma membrane proteins of hepatoma tissue culture cells. 17 63

The interaction between mouse choriomammotropin and mouse mammary glands was examined by radioreceptor assays using ovine prolactin (NIH-P-S9) iodinated by lactoperoxidase as a tracer. Mouse pituitary extracts and placental extracts were subjected to 10% acrylamide gel electrophoresis. Gels were cut into 2-mm segments after electrophoresis, and stored in 1 ml 0.05 M phosphate buffer (pH 7.4) containing 0.05 M NaCl overnight for elution. Lactating mammary tissues from D strain mice were incubated for 120 min in 1 ml Medium 199 containing 6 ng of 125I-prolactin and 0.1 ml of each eluate. Pituitary extracts displaced 125I-prolactin only at the position which coincides with the prolactin band. Displacement was observed at two positions of the gel when placental extracts were used. Relative mobilities (Rm) were 0.21 and 0.71, respectively. The slowly migrating component of choriomammotropin inhibited the binding of 125-I-prolactin more strongly that the rapidly migrating one. Neither of them was identified as a distinct band in stained gels. The molecular weight of ovine prolactin, mouse pituitary prolactin and the slowly migrating component of mouse choriomammotropin was estimated to be 23000 using disc electrophoresis but the ion charges of these hormones were considerably different.
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PMID:Binding of mouse choriomammotropin to prolactin receptors in the mouse mammary gland. 19 Dec 49

Extracts of aerobically grown Escherichia coli B exhibit both catalase and dianisidine peroxidase activities. Polyacrylamide gel electrophoresis demonstrates two distinct catalases which have been designated hydroperoxidases I and II (HP-I and HP-II) in order of increasing anodic mobility. HP-I has been purified to essential homogeneity and found to be composed of four subunits of equal size. Its molecular weight is 337,000, and it contains two molecules of protoheme IX per tetramer. Its amino acid composition is unusual, for so large a protein, in lacking half-cystine. HP-I is a very efficient catalase with an activity optimum at pH 7.5, a Km for H2O2 of 3.9 mM, and a turnover number of 9.8 x 10(5) per min. It is also a broad specificity peroxidase capable of acting upon dianisidine, guaiacol, p-phenylenediamine, and pyrogallol. Dianisidine acted as a powerful reversible inhibitor of the catalatic activity of HP-I and as a suicide substrate when HP-I functioned in its peroxidatic mode.
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PMID:Purification of the o-dianisidine peroxidase from Escherichia coli B. Physicochemical characterization and analysis of its dual catalatic and peroxidatic activities. 37 9

Two proteins (ribophorins I and II), which are integral components of rough microsomal membranes and appear to be related to the bound ribosomes, were shown to be exposed on the surface of rat liver rough microsomes (RM) and to be in close proximity to the bound ribosomes. Both proteins were labeled when intact RM were incubated with a lactoperoxidase iodinating system, but only ribophorin I was digested during mild trypsinization of intact RM. Ribophorin II (63,000 daltons) was only proteolyzed when the luminal face of the microsomal vesicles was made accessible to trypsin by the addition of sublytical detergent concentrations. Only 30--40% of the bound ribosomes were released during trypsinization on intact RM, but ribosome release was almost complete in the presence of low detergent concentrations. Very low glutaraldehyde concentrations (0.005--0.02%) led to the preferential cross-linking of large ribosomal subunits of bound ribosomes to the microsomal membranes. This cross-linking prevented the release of subunits caused by puromycin in media of high ionic strength, but not the incorporation of [3H]puromycin into nascent polypeptide chains. SDS-acrylamide gel electrophoresis of cross-linked samples a preferential reduction in the intensity of the bands representing the ribophorins and the formation of aggregates which did not penetrate into the gels. At low methyl-4-mercaptobutyrimidate (MMB) concentrations (0.26 mg/ml) only 30% of the ribosomes were cross-linked to the microsomal membranes, as shown by the puromycin-KCl test, but membranes could still be solubilized with 1% DOC. This allowed the isolation of the ribophorins together with the sedimentable ribosomes, as was shown by electrophoresis of the sediments after disruption of the cross-links by reduction. Experiments with RM which contained only inactive ribosomes showed that the presence of nascent chains was not necessary for the reversible cross-linking of ribosomes to the membranes. These observations suggest that ribophorins are in close proximity to the bound ribosomes, as may be expected from components of the ribosome-binding sites.
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PMID:Proteins of rough microsomal membranes related to ribosome binding. II. Cross-linking of bound ribosomes to specific membrane proteins exposed at the binding sites. 41 74

Optimal conditions were established for specific labelling of the surface proteins of mouse erythrocytes using lactoperoxidase-catalyzed radioiodination. The levels of H2O2 and I-, and cell concentrations required for restriction of haemoglobin labelling to less than 5% of the total 125I-protein, were different for radioiodination employing direct H2O2 addition or generation of H2O2 with glucose oxidase plus glucose. Preparation of mouse erythrocyte ghosts by hypotonic lysis caused loss of some minor labelled proteins present on intact cells and shifts to lower molecular weights of others. It is therefore important to solubilize labelled cells directly in electrophoresis buffer to avoid artifactual degradation of labelled proteins. The extent of labelling internal cell proteins was measured by a procedure suitable for the comparison of a large number of samples: solubilized radioiodinated erythrocytes were electrophoresed on 14% acrylamide gels and the radioactivity determined in the haemoglobin band which migrates separately from other proteins. The major labelled protein on the mouse erythrocytes had an apparent molecular weight of 92,000, and may be analogous to Band 3 of the human erythrocyte.
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PMID:Optimal conditions for lactoperoxidase catalyzed radioiodination of external proteins on mouse erythrocytes. 54 20

The kinetics of binding the enzymes glucose oxidase, trypsin, and peroxidase and also bovine gamma-globulin to the macroporous carriers dialdehyde cellulose, diazotized amino polystyrene, acrolein-acrylamide copolymer, and isothiocyanate groups carrying CPG-glass was studied. It was found empirically that the increase in protein content and--if there occurred no inactivation of enzyme during binding reaction--of enzymatic activity of the enzyme-carrier complex with the reaction time can be described by saturation curves (first order hyperbolas), which represent straight lines after suitable transformation. Thereby it is possible to calculate protein content or specific activity of the enzyme-carrier complex for any moment during binding reaction. From intercepts of the obtained straight lines with the ordinate and with the abscissa, respectively, one can determine the maximum binding capacity and the maximum specific activity and from their slope the reaction rate can be obtained. If there result no straight lines for plotting enzymatic activity of the enzyme-carrier complex against binding time after transformation, then this is an indication for partial inactivation of the free or already insolubilized enzyme. From kinetic measurements it is concluded that in all cases studied by use the preceding stage in chemical fixation of the enzyme to carrier is an adsorption equilibrium. Limitation of reaction rate by diffusion as in loading an ion exchanger could not be observed.
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PMID:[Synthesis and properties of carrier-fixed enzymes. VIII. Kinetic studies of the binding velocity of enzymes to macroporous carriers]. 61 87

The effect of atmospheric oxygen on the viability of 13 strains of anaerobic bacteria, two strains of facultative bacteria, and one aerobic organism was examined. There were great variations in oxygen tolerance among the bacteria. All facultative bacteria survived more than 72 h of exposure to atmospheric oxygen. The survival time for anaerobes ranged from less than 45 min for Peptostreptococcus anaerobius to more than 72 h for two Clostridium perfringens strains. An effort was made to relate the degree of oxygen tolerance to the activities of superoxide dismutase, catalase, and peroxidases in cell-free extracts of the bacteria. All facultative bacteria and a number of anaerobic bacteria possessed superoxide dismutase. There was a correlation between superoxide dismutase activity and oxygen tolerance, but there were notable exceptions. Polyacrylamide gel electropherograms stained for superoxide dismutase indicated that many of the anaerobic bacteria contained at least two electrophoretically distinct enzymes with superoxide dismutase activity. All facultative bacteria contained peroxidase, whereas none of the anaerobic bacteria possessed measurable amounts of this enzyme. Catalase activity was variable among the bacteria and showed no relationship to oxygen tolerance. The ability of the bacteria to reduce oxygen was also examined and related to enzyme content and oxygen tolerance. In general, organisms that survived for relatively long periods of time in the presence of oxygen but demonstrated little superoxide dismutase activity reduced little oxygen. The effects of medium composition and conditions of growth were examined for their influence on the level of the three enzymes. Bacteria grown on the surface of an enriched blood agar medium generally had more enzyme activity than bacteria grown in a liquid medium. The data indicate that superoxide dismutase activity and oxygen reduction rates are important determinants related to the tolerance of anaerobic bacteria to oxygen.
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PMID:Factors related to the oxygen tolerance of anaerobic bacteria. 69 63

Cytochrome P-450 in mouse liver microsomes was characterized by SDS-polyacrylamide gel electrophoresis after intraperitoneal injection of 80 mg phenobarbital, 4.5 and 45 mg acrylamide and 60 and 600 mg methylmethacrylate per kg body weight each day for four days. Four different forms of cytochrome P-450 with molecular weights of 47,000, 50,000, 54,000 and 56,000 were identified by staining for peroxidase activity and protein. The amount of cytochrome P-450 with a molecular weight of 47,000 (MLvMcP-450(47) decreased in the phenobarbital group and in both acrylamide groups. After methylmethacrylate treatment, this form increased at the low dose but was totally repressed at the high dose. The cytochrome P-450 form with a molecular weight of 50,000 (MLvMcP-450(50) was significantly increased only in the phenobarbital group. An increase in the total amount of cytochrome P-450 was only observed following treatment with phenobarbital.
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PMID:Qualitative alterations of cytochrome P-450 in mouse liver microsomes after administration of acrylamide and methylmethacrylate. 71 47

The elctrophoretic separation in polyacrylamide gel of laccase and peroxidase isoenzymes of the lignin-degrading fungus Pleurotus ostreatus was investigated. The optimal electrophoretic conditions were found: in the electrode buffer tris-diethyl barbituric acid pH 7.0 in the gradient gel-4-10% acrylamide. Seven peroxidase isoenzymes oxidizing base benzidine and guaiacol were identified and five laccase isoenzymes reacting with specific substrates-p-phenylene diamine, alphs-naphthol, pyrogallol, hydroquinone were determined.
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PMID:[Study of oxidative enzymes of the lignin-degrading fungus Pleurotus ostreatus]. 81 2


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