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:1.10.3.3 (ascorbate oxidase)
778 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hydroxyproline-rich glycoprotein of plant cell walls is secreted from the cytoplasm as a soluble monomer which slowly becomes insolubilized. A tyrosine derivative, isodityrosine, is formed in the cell wall during this insolubilization and could serve as a protein-protein crosslink. Glycoprotein insolubilization is inhibited by peroxidase inhibitors and free radical scavengers, the most effective of which is L-ascorbate. These data support a hypothesis that the hydroxyproline-rich cell wall glycoprotein forms a covalently crosslinked wall network under the control of an extracellular peroxidase/ascorbate oxidase system.
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PMID:Insolubilization of hydroxyproline-rich cell wall glycoprotein in aerated carrot root slices. 683 3

A uricase-peroxidase coupled system, for the determination of uric acid, applied to a CentrifiChem-500 centrifugal fast analyser is described. Relatively large amounts of ascorbic acid, due to the inclusion of an ascorbate oxidase urine diluent, and hemoglobin appear not to interfere with the procedure while the incorporation of potassium ferrocyanide into the reagents has led to the near-total elimination of bilirubin interference. The incubation period is relatively short compared with other similar procedures and the one reagent system has made the procedure simple to perform. The use of sodium 2-hydroxy-3,5-dichlorobenzenesulfonate and 4-aminoantipyrene in the oxidative coupling reaction has incorporated the advantages of increased sensitivity, over phenol-4-aminoantipyrene systems, as well as the amenability of the reagent towards lyophilization or "dry-fill".
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PMID:The application of a sensitive uricase-peroxidase couple reaction to a centrifugal fast analyser for the determination of uric acid. 729 93

A simple and sensitive colorimetric assay for serum diamine oxidase (DAO) activity was based on a coupled reaction with peroxidase and a new chromogen, 10-(carboxymethyl-aminocarbonyl)-3,7-bis(dimethylamino) phenothiazine sodium salt (DA-67). In the presence of peroxidase and DA-67, peroxidase catalyzes the formation of methylene blue having an absorption maximum at 668 nm. The proposed method eliminates the interferences occurring in serum with use of ascorbate oxidase and stops the reaction with sodium diethyldithiocarbamate, leaving the methylene blue in the reaction mixture stable for about 2 h. Low normal basal values of serum DAO can be determined in the range 2.8-9.0 units/l. Since all reagents are commercially available the method is suitable for the clinical laboratory.
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PMID:Sensitive colorimetric assay of serum diamine oxidase. 807 Jan 35

A method for the detection of ascorbate peroxidase activity in native electrophoretic gels is described. The assay is based on the ability of ascorbate peroxidase to prevent the ascorbate-dependent reduction of nitroblue tetrazolium in the presence of H2O2. The method was found to be both sensitive (detection of less than 0.01 units of ascorbate peroxidase activity) and specific for ascorbate peroxidase activity. The application of the method for the detection of ascorbate peroxidase activity in protein extracts from several plant sources was investigated by comparing staining for activities of ascorbate peroxidase, horseradish peroxidase, and ascorbate oxidase and by immunodetection of ascorbate peroxidase in these extracts.
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PMID:Detection of ascorbate peroxidase activity in native gels by inhibition of the ascorbate-dependent reduction of nitroblue tetrazolium. 821 98

Ole e 1, the major allergen from olive pollen, is a glycoprotein containing a single Asn-linked glycan moiety. Rabbit antiserum against this protein has been obtained; and its immunologic cross-reactivities in Western blotting with ascorbate oxidase, horseradish peroxidase, bromelain, ovalbumin, and honeybee venom phospholipase A2 have been studied. Ascorbate oxidase, peroxidase, and bromelain are recognized by the Ole e 1 antiserum. When these three proteins are deglycosylated by periodate treatment, such an immunologic reaction does not occur. The relative affinities of these proteins have been analyzed by direct and inhibition ELISA experiments. A commercially available antibody against horseradish peroxidase has also been considered in these studies. This antibody reacts with Ole e 1 but not with the periodate-deglycosylated allergen. Horseradish peroxidase, bromelain, and ascorbate oxidase are recognized by the IgE of sera from patients who are hypersensitive to olive tree pollen. This binding is also abolished by periodate treatment. The results are interpreted in terms of the presence of an epitope in the carbohydrate moiety of Ole e 1, which would contain a xylose involved in recognition by both IgE and IgG antibodies.
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PMID:Cross-reactivity between the major allergen from olive pollen and unrelated glycoproteins: evidence of an epitope in the glycan moiety of the allergen. 864 22

The binding to concanavalin A (Con A) by pyridylaminated oligosaccharides derived from bromelain (Manalpha1,6(Xylbeta1,2) Manbeta1, 4GlcNAcbeta1,4(Fucalpha1,3)GlcNAc), horseradish peroxidase (Manalpha1,6(Manalpha1,3) (Xylbeta1,2)Manbeta1, 4GlcNAcbeta1,4(Fucalpha1,3) GlcNAc), bee venom phospholipase A2 (Manalpha1,6Manbeta1,4GlcNAcbeta1,4GlcNAc and Manalpha1,6(Manalpha1,3)Manbeta1,4GlcNAcbeta1,4 (Fucalpha1,3)GlcNAc) and zucchini ascorbate oxidase (Manalpha1,6(Manalpha1,3) (Xylbeta1,2)Manbeta1,4 GlcNAcbeta1,4GlcNAc) was compared to the binding by Man3GlcNAc2, Man5GlcNAc2 and the asialo-triantennary complex oligosaccharide from bovine fetuin. While the fetuin oligosaccharide did not bind, bromelain, zucchini, Man2GlcNAc2 and horseradish peroxidase were retarded (in that order). The alpha1,3-fucosylated phospholipase, Man3GlcNAc2 and Man5GlcNAc2 structures were eluted with 15 mM alpha-methylmannoside. It is concluded that core alpha1,3-fucosylation has little or no effect on ConA binding while xylosylation decreases affinity for ConA. In a parallel study comparing the endoglycosidase D (Endo D) sensitivities of Man3GlcNAc2, IgG-derived GlcNAcbeta1, 2Manalpha1,6(GlcNAcbeta1,2Manalpha1,3)Manbeta1,+ ++4GlcNAcbeta1,4(Fucalpha1,6)GlcNAc, the phospholipase Manalpha1,6(Manalpha1,3) Manbeta1, 4GlcNAcbeta1,4(Fucalpha1,3)GlcNAc, and horseradish and zucchini pyridylaminated N-linked oligosaccharides, it was found that only the Man3GlcNAc2 structure was cleaved. The IgG structure was sensitive only when beta-hexosaminidase was also present. Thus, in contrast to core alpha1,6-fucosylated structures, such as those present in mammals, the presence of core alpha1,3-fucose, as found in structures from plants and insects, and/or beta1,2-xylose, as found in plants, causes resistance to Endo D.
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PMID:Concanavalin A binding and endoglycosidase D resistance of beta1,2-xylosylated and alpha1,3-fucosylated plant and insect oligosaccharides. 955 83

Cultured cells of tobacco BY2 secrete more than 100 proteins into culture medium. Six major proteins were purified, and partial protein sequences were determined. Five of them were found to be similar to an ascorbic acid oxidase, three peroxidase isozymes and a beta-1,3-exoglucanase, respectively. A cDNA clone encoding the remaining polypeptide, whose amino acid sequence showed no similarity with earlier reported proteins, was isolated. It encoded a putative 27 kDa protein of 242 amino acids with resemblance to WCI-5, a wheat protein induced by benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) which activates genes involved in systemic acquired resistance. Transcripts of this clone accumulated upon tobacco mosaic virus infection, mechanical wounding and drought treatment, an induction profile that satisfies the definition of pathogenesis-related (PR) proteins by van Loon et al. (Plant Mol. Biol. Rep. 12 (1994) 245). No similar PR proteins have so far been reported, and therefore our newly designated NtPRp27 points to the existence of a novel PR protein family in tobacco plants.
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PMID:Secreted proteins of tobacco cultured BY2 cells: identification of a new member of pathogenesis-related proteins. 1079 17

A method has been developed which allows the analysis of glycoproteins separated by SDS-PAGE. The procedure, though applicable to N-glycosylated glycoproteins of any origin, is particularly devised for glycoproteins potentially containing fucose in alpha1,3-linkage to the reducing GlcNAc as may be found in plants and invertebrates, e.g., insects and parasitic helminths. Starting with an established procedure for mass spectrometric peptide mapping, the analysis of N-glycans by matrix-assisted laser desorption/ionization mass spectrometry involved the use of peptide:N-glycosidase A, a triphasic microcolumn for sample cleanup, and a new matrix mixture consisting of 2,5-dihyhydroxybenzoic acid, 1-hydroxyisoquinoline, and arabinosazone. The method was tested on proteins with N-glycans of known structure, i.e., as horseradish peroxidase, zucchini ascorbate oxidase, soybean agglutinin, honeybee venom hyaluronidase, bovine ribonuclease B, and bovine fetuin. An electrophoretic band corresponding to 4 microg of glycoprotein was generally sufficient to allow detection of the major N-glycan species. As an additional benefit, a peptide mass map is generated which serves to identify the analyzed protein. The method was applied to glycoprotein allergens whose glycan structures were unknown. Ara h 1 and Ole e 1, major allergens from peanut and olive pollen, respectively, contained mainly xylosylated N-glycans with the composition Man(3(-4))XylGlcNAc(2) in the case of Ara h 1 and GlcNAc(1-2)Man(3)XylGlcNAc(2) in the case of Ole e 1 where also some GlcNAc(0-2)Man(3)XylFucGlcNAc(2) was found.
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PMID:N-Glycan analysis by matrix-assisted laser desorption/ionization mass spectrometry of electrophoretically separated nonmammalian proteins: application to peanut allergen Ara h 1 and olive pollen allergen Ole e 1. 1099 64

Ascorbic acid (vitamin C) is an abundant component of plants. It reaches a concentration of over 20 mM in chloroplasts and occurs in all cell compartments, including the cell wall. It has proposed functions in photosynthesis as an enzyme cofactor (including synthesis of ethylene, gibberellins and anthocyanins) and in control of cell growth. A biosynthetic pathway via GDP-mannose, GDP-L-galactose, L-galactose, and L-galactono-1,4-lactone has been proposed only recently and is supported by molecular genetic evidence from the ascorbate-deficient vtc 1 mutant of Arabidopsis thaliana. Other pathways via uronic acids could provide minor sources of ascorbate. Ascorbate, at least in some species, is a precursor of tartrate and oxalate. It has a major role in photosynthesis, acting in the Mehler peroxidase reaction with ascorbate peroxidase to regulate the redox state of photosynthetic electron carriers and as a cofactor for violaxanthin de-epoxidase, an enzyme involved in xanthophyll cycle-mediated photoprotection. The hypersensitivity of some of the vtc mutants to ozone and UV-B radiation, the rapid response of ascorbate peroxidase expression to (photo)-oxidative stress, and the properties of transgenic plants with altered ascorbate peroxidase activity all support an important antioxidative role for ascorbate. In relation to cell growth, ascorbate is a cofactor for prolyl hydroxylase that posttranslationally hydroxylates proline residues in cell wall hydroxyproline-rich glycoproteins required for cell division and expansion. Additionally, high ascorbate oxidase activity in the cell wall is correlated with areas of rapid cell expansion. It remains to be determined if this is a causal relationship and, if so, what is the mechanism. Identification of the biosynthetic pathway now opens the way to manipulating ascorbate biosynthesis in plants, and, along with the vtc mutants, this should contribute to a deeper understanding of the proposed functions of this multifaceted molecule.
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PMID:Ascorbic acid in plants: biosynthesis and function. 1100 3

Pycnogenol, an extract from French maritime pine bark (PBE), is a complex mixture of bioflavonoids with reported protective effects against disease. PBE is an effective scavenger of reactive oxygen species, and its main constituents are procyanidins of various chain lengths. To find out the biochemical basis of action of PBE on enzyme activity, involvement of its redox activity and direct binding to the enzyme in its subsequent action on enzyme activity have been investigated. PBE dose-dependently inhibited the activities of xanthine oxidase, xanthine dehydrogenase, horseradish peroxidase, and lipoxygenase, but it did not affect the activities of glucose oxidase, ascorbate oxidase, or elastase. To characterize the mechanism of PBE action, studies were focused on xanthine oxidase and glucose oxidase. Under non-denaturing conditions, PBE changed the electrophoretic mobility of xanthine oxidase but not of glucose oxidase. Gel filtration chromatography confirmed higher molecular weight complexes of xanthine oxidase and xanthine dehydrogenase in the presence of PBE. It was found that hydrophobic bonding might be the dominant mode of interaction between PBE and xanthine oxidase. The importance of the binding in the effect of PBE on enzyme activity was supported by the observation that PBE binds to and inhibits catalase, but not superoxide dismutase. However, no correlation was found between superoxide/hydroxyl radical scavenging activity and the inhibitory effect on xanthine oxidase activity of PBE, various purified flavonoids, or other complex mixtures of bioflavonoids. The results indicate that PBE selectively inhibits xanthine oxidase through binding to the enzyme rather than by the redox activity.
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PMID:Enzyme inhibition and protein-binding action of the procyanidin-rich french maritime pine bark extract, pycnogenol: effect on xanthine oxidase. 1108 30


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