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)

Virion RNA of poliovirus type 1 has been analyzed for the linkage between genome-protein VPg and the polyribonucleotide chain. Hydrolysis of the linkage with acid or alkali and enzymatic degradation lead to the conclusion that the bond is neither a phosphodiester such as nucleotidyl-(P-O)-serine (or threonine) nor a phosphoramidate such as nucleotidyl-(P-N)-amino acid. VPg-RNA can be iodinated by the Bolton and Hunter reagent [iodinated 3-(4-hydroxyphenyl)propionic acid N-hydroxysuccinimide ester] but not by the chloramine-T or lactoperoxidase procedures, an observation suggesting that VPg does not contain accessible tyrosine. However, VPg can be labeled with [3H]tyrosine in vivo. Hydrolysis of VPg-[32P]pUp with 5.6 M HCl at 110 degrees yielded 32P-labeled O4-(3'-phospho-5'-uridylyl)tyrosine that could be cleaved with micrococcal nuclease to O4-[32P]phosphotyrosine and uridine 3'-[32P]phosphate. These data establish that VPg is linked to the poliovirus genome by a bond between the O4 of tyrosine and the 5'-P atom of the terminal uridylic acid residue. The 5' end of polio genome RNA can now be described as VPg(Tyr-O)-pU-U-A-A-A-A-C-A-G.
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PMID:O4-(5'-uridylyl)tyrosine is the bond between the genome-linked protein and the RNA of poliovirus. 21 3

Polymorphonuclear leukocytes (PMNs) are one of the main sources of enzymes responsible for tissue damage in inflammatory processes. These enzymes are stored in two types of cytoplasmic granules. Azurophil granules contain lysosomal hydrolases, neutral serine proteinases, and bactericidal elements (myeloperoxidase and lysozyme). Specific granules contain collagenase, lysozyme and lactoferrin but lack lysosomal hydrolases. PMNs store all four classes of tissue proteinases, carboxyl, thiol and serine proteinases in the azurophil granules, and metallo proteinases in the specific granules. Three serine proteinases have been identified, elastase, cathepsin G and a third enzyme, which together account for a large proportion of the protein of the azurophil granules. In the course of phagocytic events, all these enzymes are released extracellularly. The neutral proteinases degrade proteoglycans and collagen. In vitro, they stimulate B-lymphocytes, which suggests that they may have immuno-potentiating activity when they are released at sites of chronic inflammation.
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PMID:The polymorphonuclear leukocyte. 34 82

The membrane of kidney microvilli is richly endowed with peptidases. Present information is that there are at least eight examples located in this membrane. Three of the group are known to be among the major proteins that can be identified by dodecyl sulphate electrophoresis of the purified microvillus fraction. These three peptidases, aminopeptidase M, serine peptidase (dipeptidyl peptidase IV) and neutral endopeptidase can be labelled by lactoperoxidase iodination from either the luminal or the inner surfaces of the membrane, a result consistent with the view that the polypeptide chains span the microvillus membrane. The serine peptidase has been purified by two methods, permitting a comparison of the detergent-released and proteinase-released forms. The two forms differ in the presence and absence of the hydrophobic anchor that secures the enzyme to the membrane. Preliminary studies support the view that this hydrophobic domain is relatively small and that it includes the N-terminal region of the polypeptide chain.
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PMID:Kidney microvillus peptidases--are they transmembrane proteins? 61 79

Peroxidase-catalyzed halogenation reactions have been established as being important in the biosynthesis of the hormone thyroxine and in biological defense mechanisms. Recently these reactions have been recognized as valuable tools for the study of proteins as well as their arrangement in macromolecular structures. The pathways of peroxidase catalyses can be accommodated within the framework of the classical Chance-George mechanism. This implies that the initial steps of the reaction invariably involve oxidation of peroxidases by peroxides--and that the resulting derivative, compound I, is the oxidant of the halide ions. Such reactions may result either in the formation of hypohalous acids, or in halogenation of the enzyme apoprotein, followed by transhalogenation to substrate for halogenation. Chloro- and myeloperoxidases catalyze oxidation of all halide ions, except F-; oxidation of bromide and iodide is mediated by lactoperoxidase, but horseradish peroxidase only oxidizes iodide. All of the above enzymes except horseradish will oxidize the pseudo halide thiocyanate. The origins of this differentiation remain to be defined, but they presumably reflect significant variation in oxidation potential of different peroxidase-peroxide derivatives, rather than constraints on the peroxidase-donor interactions. As pointed out above, halogenation of the amino acids tyrosine and histidine or these residues in proteins can take place on the enzyme. This makes lactoperoxidase-catalyzed iodination selective. The amino acid residues in proteins that are iodinated depend not only on reactivity of the amino acid residue but also on its geometric location. Thus lactoperoxidase-catalyzed iodination can be a useful tool in the study of protein structure and function. It is also useful in establishing the geometric position of proteins within macromolecular structures. Thyroid peroxidase catalyzes iodination of thyroglobulin and is involved in a second important step, the coupling of the iodotyrosines to form thyroxine or triiodothyronine. A proposed mechanism for this reaction suggests that the oxidation is mediated by the iodoenzyme derivative mentioned above followed by a prototropic rearrangement and scission to form the ether bound of thyronine and a serine residue on thyroglobulin.
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PMID:Peroxidase-catalyzed halogenation. 78 62

Degradation of methyl mercury (MeHg) and ethyl Hg (EtHg) with reactive oxygens was studied in vitro by using peroxidase-hydrogen peroxide (H2O2)-halide and rose bengal-ultraviolet light A systems. For this purpose, the direct determination method for inorganic Hg was employed. Both systems could effectively degrade EtHg, and MeHg to some extent. Degradation of MeHg and EtHg with the myeloperoxidase (MPO)-H2O2-chloride system was inhibited by MPO inhibitors (cyanide and azide), catalase, hypochlorous acid (HOCI) scavengers (glycine, alanine, serine and taurine), 1,4-diazabicyclo[2,2,2]octane and 2,5-dimethylfuran, but not by hydroxyl radical scavengers (ethanol and mannitol). Iodide was more effective than chloride as the halide component. Lactoperoxidase (LPO) could substitute for MPO in the iodide, but not the chloride system. With MPO-H2O2-chloride, MPO-H2O2-iodide and LPO-H2O2-iodide systems, we observed the increased degradation of EtHg in deuterium oxide (D2O) medium better than that in H2O medium. The D2O effect upon MeHg degradation was extremely weak. These results suggested that HOCl (or HOI) might be also capable of degrading MeHg and EtHg, besides the hydroxyl radical already reported by us. Singlet oxygen could degrade EtHg but not MeHg.
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PMID:Degradation of methyl and ethyl mercury into inorganic mercury by other reactive oxygen species besides hydroxyl radical. 131 15

An enzyme-linked immunosorbent assay (ELISA) for quantitation of natural and recombinant plasminogen activators containing the serine protease domain (B-chain) of urokinase-type plasminogen activator (u-PA) was developed, based on two murine monoclonal antibodies, MA-4D1E8 and MA-2L3, raised against u-PA and reacting with non-overlapping epitopes in the B-chain. MA-4D1E8 was coated on microtiter plates and bound antigen was quantitated with MA-2L3 conjugated with horseradish peroxidase. The intra-assay, inter-assay and inter-dilution coefficients of variation of the assay were 6%, 15% and 9%, respectively. Using recombinant single-chain u-PA (rscu-PA) as a standard, the u-PA-related antigen level in normal human plasma was 1.4 +/- 0.6 ng/ml (mean +/- SD, n = 27). The ELISA recognized the following compounds with comparable sensitivity: intact scu-PA (amino acids, AA, 1 to 411), scu-PA-32k (AA 144 to 411), a truncated (thrombin-derived) scu-PA comprising AA 157 to 411, and chimeric t-PA/u-PA molecules including t-PA(AA1-263)/scu-PA(AA144-411), t-PA(AA1-274)/scu-PA(AA138-411) and t-PA(AA87-274)/scu-PA(AA138-411). Conversion of single-chain to two-chain forms of u-PA or inhibition of active two-chain forms with plasminogen activator inhibitor-1 or with the active site serine inhibitor phenyl-methyl-sulfonyl fluoride, did not alter the reactivity in the assay. In contrast, inactivation with alpha 2-antiplasmin or with the active site histidine inhibitor Glu-Gly-Arg-CH2Cl resulted in a 3- to 5-fold reduction of the reactivity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:An enzyme-linked immunosorbent assay for urokinase-type plasminogen activator (u-PA) and mutants and chimeras containing the serine protease domain of u-PA. 137 17

Serum samples from 83 patients (42 women, 41 men, mean age 41 [19-85] years) with chronic inflammatory bowel diseases (ulcerative colitis: n = 41, Crohn's disease: n = 42) of differing degrees of activity were tested for antineutrophil cytoplasmic antibodies (ANCA) by immunofluorescence microscopy and various ELISA techniques. Seven patients with ulcerative colitis and one with Crohn's disease were suffering from associated primary sclerosing cholangitis. ANCA were detected in 18 sera, 13 from patients with ulcerative colitis (31.7%) and five from patients with Crohn's disease (11.9%). Six of the eight patients with primary sclerosing cholangitis were ANCA-positive. Nine sera showed a cytoplasmic (c-ANCA-) pattern and 9 others showed a partially atypical perinuclear (p-ANCA-) pattern. Among the ANCA-positive sera, ELISA techniques showed that two had antibodies against serine proteinase 3, two against lactoferrin, two against elastase and one against myeloperoxidase. There was no correlation between the anatomical pattern or activity of the disease and the presence of ANCA. The antineutrophil cytoplasm antibodies demonstrable in chronic inflammatory bowel disease appear to be directed against so far unknown antigens. They are particularly frequent in patients with associated primary sclerosing cholangitis.
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PMID:[Antineutrophil cytoplasmic antibodies in chronic inflammatory bowel diseases]. 139 27

Colonization in the respiratory tracts of cystic fibrosis (CF) patients by mucoid Pseudomonas aeruginosa correlates with the progression of bronchial airway pathology. There is a direct correlation between the incidence of Pseudomonas colonization and age, clinical score, extent of pulmonary disease, severity of radiographic changes, and level of serum immunoglobulins. The central propensity to Pseudomonas colonization in patients with CF is not freely understood, but we discuss the acquisition and persistence of P aeruginosa in the CF airway. Elucidation of pathogenetic mechanisms of CF inflammatory airways disease is the first essential step to initiating novel therapies. It has been difficult to prove that the ability of P aeruginosa to adhere to the respiratory epithelium and provide selective advantage for this gram-negative bacillus over other potential pathogens for infection in the CF airway. However, flexible filaments (pili) extending from the Pseudomonas cell wall are thought to medicate epithelial cell adherence for nonmucoid P aeruginosa, and similarly, the gelatinous exopolysaccharide alginate produced by mucoid variants of P aeruginosa seems to be the adhesive to tracheal cells. Following the signal event of adherence, this bacterial pathogen competes successfully for iron cofactor and multiplies, releasing proteases with broad substrate specificities that dramatically alter the airway antiprotease screen, and the pathogen creates defects in local antibacterial defenses. Lung inflammation in CF is characterized by massive neutrophil infiltration. Although critical to host defense, neutrophils also cause progressive airway damage by release of bioactive lipids, oxygen metabolites, and granule enzymes such as hydrolases, myeloperoxidase (MPO), lysozyme, and neutral serine proteases. The necessarily circumscribed discussion that follows will focus narrowly on the host cell-derived factors (macrophages and neutrophils) proposed as important components in this pathogenetic scheme.
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PMID:Emergence and persistence of Pseudomonas aeruginosa in the cystic fibrosis airway. 147 41

We previously constructed plasmids for synthesis of glutathione-peroxidase (GPx) mutants in an Escherichia coli expression system. In these recombinant proteins either cysteine ([Cys]GPx mutant) or serine ([Ser]GPx mutant) were present in place of the active-site selenocysteine (SeCys) of the natural enzyme. We have now investigated GPx activity of [Cys]GPx and [Ser]GPx mutants. Enzyme assays performed on preparations of these partially purified proteins demonstrated that the [Cys]GPx mutant exhibited a significant GPx activity, unlike the [Ser]GPx mutant. Purification of [Cys]GPx was performed in two steps of ion-exchange chromatography giving a 98% homogenous protein in 50% yield. The purified [Cys]GPx protein was shown to be a symmetrical tetramer by the means of gel-filtration HPLC and SDS/PAGE. Two isoelectric points were found (6.8 and 7.2) which may reflect two different oxidation states of the mutant protein. The GPx activity of the [Cys]GPx mutant was optimal at pH 8.5. The [Cys]GPx mutant had a specific activity approximately 1000-fold smaller than that of the natural enzyme, and was very easily inactivated by hydroperoxides. Inhibition of the activity with iodoacetate determined a pKa of 8.3, presumably that of the active-site cysteine. Unlike that of SeGPx, the GPx activity of [Cys]GPx was only slightly inhibited by mercaptosuccinate. We discuss hypothetical mechanistic constraints of either catalytic cycle, which may explain such results.
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PMID:Purification and properties of a recombinant sulfur analog of murine selenium-glutathione peroxidase. 157 13

Anti-neutrophil antibodies have been shown in sera from patients with a variety of inflammatory diseases. Those reacting with components of neutrophil cytoplasm are associated with systemic vasculitis. Both nuclear and perinuclear staining patterns on human neutrophils have been reported using sera from patients with inflammatory bowel disease. We have evaluated the reactivity against human neutrophils of sera from 100 patients with inflammatory bowel disease, 14 disease controls, and 20 normal volunteers. Altogether 27/50 (54%) sera from patients with ulcerative colitis contained antibodies that reacted with cytospun ethanol fixed neutrophils compared with 5/50 (10%) from Crohn's disease (p less than 0.001) and 0/34 control sera (p less than 0.001). All seven sera from patients with proctitis alone were negative (p less than 0.01). There was no correlation between presence or titre of anti-neutrophil antibodies and either disease activity or treatment. Positive sera gave three different staining patterns on human neutrophils. The predominant pattern was perinuclear (17/32); 12 sera gave a cytoplasmic and three a homogeneous nuclear staining pattern. None of the patients or the controls had antibodies to myeloperoxidase, elastase, or serine proteinase 3, all of which are recognised by anti-neutrophil cytoplasmic antibodies. Only 2/27 sera positive by indirect immunofluorescence reacted with an extract of neutrophil primary granules. In conclusion, anti-neutrophil antibodies occur more commonly in ulcerative colitis than in Crohn's disease or control subjects and the anti-neutrophil antibodies found in inflammatory bowel disease are different from those associated with vasculitis.
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PMID:Anti-neutrophil antibodies in inflammatory bowel disease: prevalence and diagnostic role. 161 85


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