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)

In addition to well-known cell wall peroxidases, there is now evidence for the presence of this enzyme at the plasma membrane of the plant cells (surface peroxidase). Both are able to catalyze, through a chain of reactions involving the superoxide anion, the oxidation of NADH to generate hydrogen peroxide. The latter is oxidized by other wall-bound peroxidases to convert cinnamoyl alcohols into radical forms, which, then polymerize to generate lignin. However, there are other enzymes at the surface of plasma membranes capable of generating hydrogen peroxide (cell wall polyamine oxidase), superoxide anion (plasma membrane Turbo reductase), or both (plasma membrane flavoprotein?). These enzymes utilize NAD(P)H as a substrate. The Turbo reductase and the flavoprotein catalyze the univalent reduction of Fe3+ and then of O2 to produce Fe2+ and O2-., respectively. The superoxide anion, in the acidic environment of the cell wall, may then dismutate to H2O2. These superoxide anion- and hydrogen peroxide-generating systems are discussed in relation to their possible involvement in physiological and pathological processes in the apoplast of plant cells.
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PMID:Generation of superoxide anion and hydrogen peroxide at the surface of plant cells. 165 Jul 79

Few nonphagocytic cells are known to generate reactive oxygen intermediates. Based on horseradish peroxidase-dependent, catalase-inhibitable oxidation of fluorescent scopoletin, seven human tumor cell lines constitutively elaborated H2O2 at rates (up to 0.5 nmol/10(4) cells/h) large enough that cumulative amounts at 4 h were comparable to the amount of H2O2 produced by phorbol ester-triggered neutrophils. Superoxide dismutase-inhibitable ferricytochrome c reduction was detectable at much lower rates. H2O2 production was inhibited by diphenyleneiodonium, a flavoprotein binder (concentration producing 50% inhibition, 0.3 microM), and diethyldithiocarbamate, a divalent cation chelator (concentration producing 50% inhibition, 3 microM), but not by cyanide or azide, inhibitors of electron transport, or by agents that inhibit xanthine oxidase, polyamine oxidase, or cytochrome P450. Cytochrome b559, present in human phagocytes and lymphocytes, was undetectable in these tumor cells by a sensitive spectrophotometric method. Mouse fibroblasts transfected with human tyrosinase complementary DNA made melanin, but not H2O2. Constitutive generation of large amounts of reactive oxygen intermediates, if it occurs in vivo, might contribute to the ability of some tumors to mutate, inhibit antiproteases, injure local tissues, and therefore promote tumor heterogeneity, invasion, and metastasis.
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PMID:Production of large amounts of hydrogen peroxide by human tumor cells. 184 17

Rat liver peroxisomal polyamine oxidase activity was determined under various physiological conditions by using the peroxidase method with phenol and 4-aminoantipyrine. N1-Acetylpolyamines such as N1-acetylspermine and N1-acetylspermidine were better substrates than the free polyamines. The polyamine oxidase activity in rat peroxisomes increased significantly when cell proliferation was high. The activity began to appear in fetal liver at the 16th approximately 18th day of pregnancy and peaked in neonatal liver on the first day (approx. 1.7-times higher than in adult liver). In regenerating rat liver, only polyamine oxidase activity among the peroxisomal enzymes tested was increased considerably 12 h after partial hepatectomy (approx. 2.8-fold over the control liver). Finally, the enzyme activity was significantly increased by administration of clofibrate, a peroxisome proliferator, which also causes hepatomegaly. In all cases, the increase in polyamine oxidase activity was not more than 3-fold. Since the level of polyamine oxidase activity in the normal liver is more than adequate in relation to the level of the substrates, the slight but significant increase under conditions of cell proliferation may have a role in modulating levels of polyamines in the proliferating liver tissue.
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PMID:Changes in polyamine-oxidizing capacity of peroxisomes under various physiological conditions in rats. 271 74

A new enzymatic method for the quantitation of spermine in human semen, based on the specific reaction of barley seedling polyamine oxidase with spermine, is described. Small amounts of human semen were incubated with the polyamine oxidase; hydrogen peroxide formed in the oxidase reaction was measured photometrically by coupling 4-aminoantipyrine with N-ethyl-N-(3-methylphenyl)-N'-acetylethylenediamine in the presence of peroxidase. The detection limit of spermine of this method was about 10 nmol per tube. The mean level of spermine in human semen was 2.41 mumol/ml; the levels in vaginal fluid, saliva, serum, and urine were below the detectable limit by this procedure.
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PMID:A new enzymatic method for quantitation of spermine in human semen. 708 Jun 85

This thesis describes new and original experimental results on Cu-dependent amine oxidases (CAOs), which show that these enzymes can be conveniently and specifically detected in situ using a peroxidase-coupled activity staining method with 4-Cl-1-naphtole as hydrogen donor substrate. Even more sensitive in situ detection can be achieved using a chemiluminescence-based coupled peroxidase assay which was applied to show that human placenta CAO activity is confined to maternal vessels. A general purification scheme for CAOs is described, and applied to purification of different CAOs. Peptide maps and immunological crossreactivity studies with monoclonal antibodies raised against the purified enzymes showed that they were closely related. Amino acid sequence data for the bovine serum CAO showed that they form a separate group (E.C. 1.4.3.6) with no homology to other enzymes. A cDNA sequence was obtained on the basis of the amino acid sequence data, and this was found to encode a bovine lung CAO, related to bovine serum CAO. The genes for bovine lung and bovine serum CAO are characterized, and Southern blotting analysis of bovine chromosomal DNA shows the existence of a least one more bovine CAO. The purification of human neutrophil CAO is attempted, but it is described how lactoferrin, a protein with many properties in common with CAOs, and with a low degree of sequence identity can account for many observations on human neutrophil CAO. The products of bovine serum CAO oxidation of polyamines are characterised, and 3-aminopropanal is found to be the principal aminoaldehyde produced. Finally, a polyamine-stimulated binding of human placenta CAO to single-stranded DNA is described, and it is reported that the DNA-bound CAO is enzymically active and that the oxidation of DNA-bound polyamines leads to degradation of DNA. In addition to the experimental results, the properties of polyamines and Cu-dependent amine oxidases are reviewed. The polyamines spermidine and spermine interact specifically with nucleic acids and several other molecules. They are synthesised from putrescine, which is a key regulatory molecule formed from ornithine by ornithine decarboxylase, a highly inducible and regulated enzyme. The polyamines can be converted to putrescine by CAOs or spermidine/spermine acetyltransferase and polyamine oxidase. Putrescine is degraded by CAOs, which are also involved in degradation of histamine, a mediator of inflammatory processes. CAOs catalyse the general reaction: R1CH2NHR2 + O2 + H2O-->R1CHO + R2NH2 + H2O2 and in addition to the catabolism of putrescine and histamine CAOs are involved in regulation of growth and apoptosis by to the generation of aminoaldehydes and hydrogen peroxide which have growth inhibitory properties. Several homologous CAOs have been purified and characterized and they form a family with two subgroups. They are homodimers with a relative molecular weight of 180,000 and contain Cu2+ and a modified tyrosine, topaquinone, in the active site. CAOs are present in most tissues with highest amounts in intestine, kidneys, liver and placenta, but the cellular distributions and functions of CAOs are still poorly described, partly due to the use of many different assays and partly due to a broad substrate specificity of the enzymes. However, polyamines and CAOs seem to form a universal system contributing to regulation of growth, differentiation, and apoptosis.
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PMID:Mammalian Cu-containing amine oxidases (CAOs): new methods of analysis, structural relationships, and possible functions. 1066 4

Hydrogenperoxide (H(2)O(2)) is an end product of diamine and polyamine oxidation by their respective oxidase enzymes. A new sensitive assay method is based on a H(2)O(2)-titanium (Ti) complex formation as an indicator of H(2)O(2) production due to polyamine oxidation. The orange-yellow coloured H(2)O(2)-Ti complex was measured at 410 nm in a Shimadzu spectrophotometer. The assay conditions for maximum diamine oxidase (DAO) and polyamine oxidase (PAO) as standardized here using the hypocotyl tissues of Vigna catjang Endl. cv Pusa Barsati consisted of pH 7.4 (40 mM potassium phosphate buffer), 3 mM substrate (putrescine or spermine), 37 degrees C incubation temperature and 30 min incubation time in the presence of catechol (10(-2) M) used as an inhibitor of both peroxidase and catalase activity. The method described here was significantly more sensitive than the starch-iodide method [T.A. Smith, Biochem. Biophys. Res. Commun. 41 (1970) 1452-1456], which could be improved further if measured under the same assay conditions as described for the H(2)O(2)-Ti method. Sensitivity of the present method was tested by assaying DAO/PAO activity in auxin treated hypocotyls of Vigna and comparing it with the starch-iodide method in two other plant samples.
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PMID:A rapid and sensitive assay method for measuring amine oxidase based on hydrogen peroxide-titanium complex formation. 1096 Jul 28

An electron-microscopic cytochemical method was used to localize diamine oxidase (DAO) in pea and polyamine oxidase (PAO) in maize (Zea mays L.). The method, based on the precipitation of amine-oxidase-generated H2O2 by CeCl3, was shown to be specific for DAO and PAO and permitted their localization in plant tissues with a high degree of resolution. Both enzymes are localized exclusively in the cell wall. Both DAO- and PAO-activity staining is most intense in the middle lamellar region of the wall and in cells exhibiting highly lignified walls. The oxidases could provide H2O2 for peroxidase-mediated cross-linking reactions in the cell wall and may, in this capacity, play a role in the regulation of plant growth.
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PMID:Electron-microscopic cytochemical localization of diamine and polyamine oxidases in pea and maize tissues. 1153 70

The localization and activities of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4) together with polyamine levels have been investigated in developing grains of barley (Hordeum vulgare L.). DAO (pH 7.5) is present mainly in vascular tissue and its neighbouring cells, namely chalazal cells and nucellar projection, while PAO (pH 6.0) is mainly localized in the chlorenchymatous cells of the crease and at the base of the vascular tissue. Activities of both these enzymes appear to be independently-regulated, as DAO activity increased steadily throughout grain development while PAO activity was higher during the early stages of grain filling, declined thereafter and again increased towards maturity. The maximum activities of DAO coincided with the maximum content of putrescine while the levels of PAO did not seem to be directly correlated with spermidine or spermine contents. Isoelectric focusing (IEF) of DAO and PAO activities revealed the presence of bands at 30 and 45 DPA. The possible involvement of DAO and PAO in the supply of H(2)O(2) to peroxidase-catalysed reactions in the chalazal cells during grain filling is discussed.
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PMID:Diamine oxidase is involved in H(2)O(2) production in the chalazal cells during barley grain filling. 1188 87

In this study, the specific contribution of polyamine oxidase (PAO), a hydrogen peroxide (H2O2)-producing enzyme, to the oxidative burst induced in maize mesocotyl by the phosphatase inhibitor cantharidin was examined. For this purpose, a pharmacological approach was applied using, either in vitro or in vivo, two strong inhibitors of maize PAO (MPAO), N-prenylagmatine (G3) and its structural analogue Ro5, as well as diphenyleneiodonium (DPI), an inhibitor of the phagocyte NAD(P)H oxidase. DPI was shown to be a good MPAO inhibitor in vitro. G3, Ro5, and DPI were very effective in inhibiting in vivo the extracellular accumulation of H2O2 that is released by mesocotyl segments upon spermidine supply. G3 and Ro5 did not show any inhibition in vitro of either horseradish peroxidase or barley oxalate oxidase. Moreover, G3 and Ro5 did not inhibit the extracellular accumulation of superoxide radical that is released in vivo upon NADH supply. G3, Ro5, and DPI strongly affected H2O2 production induced in maize mesocotyl by cantharidin. Histochemical localization of H2O2 in cantharidin-treated mesocotyl cross-sections revealed an increase of H2O2-specific staining in the epidermal and subepidermal tissues. The effect was also inhibited by G3 and DPI. Moreover, an increase in MPAO activity was observed in the same tissues upon cantharidin treatment. All these data suggest that G3 and Ro5 behave as powerful and selective inhibitors of MPAO activity either in vitro or in vivo and that MPAO activity contributes to a major part of the cantharidin-induced H2O2 synthesis in the apoplastic milieu of maize mesocotyl.
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PMID:Flavin-containing polyamine oxidase is a hydrogen peroxide source in the oxidative response to the protein phosphatase inhibitor cantharidin in Zea mays L. 1683 49

Hydrogen peroxide (H(2)O(2)) is involved in plant defense responses that follow mechanical damage, such as those that occur during herbivore or insect attacks, as well as pathogen attack. H(2)O(2) accumulation is induced during wound healing processes as well as by treatment with the wound signal jasmonic acid. Plant polyamine oxidases (PAOs) are H(2)O(2) producing enzymes supposedly involved in cell wall differentiation processes and defense responses. Maize (Zea mays) PAO (ZmPAO) is a developmentally regulated flavoprotein abundant in primary and secondary cell walls of several tissues. In this study, we investigated the effect of wounding on ZmPAO gene expression in the outer tissues of the maize mesocotyl and provide evidence that ZmPAO enzyme activity, protein, and mRNA levels increased in response to wounding as well as jasmonic acid treatment. Histochemically detected ZmPAO activity especially intensified in the epidermis and in the wound periderm, suggesting a tissue-specific involvement of ZmPAO in wound healing. The role played by ZmPAO-derived H(2)O(2) production in peroxidase-mediated wall stiffening events was further investigated by exploiting the in vivo use of N-prenylagmatine (G3), a selective and powerful ZmPAO inhibitor, representing a reliable diagnostic tool in discriminating ZmPAO-mediated H(2)O(2) production from that generated by peroxidase, oxalate oxidase, or by NADPH oxidase activity. Here, we demonstrate that G3 inhibits wound-induced H(2)O(2) production and strongly reduces lignin and suberin polyphenolic domain deposition along the wound, while it is ineffective in inhibiting the deposition of suberin aliphatic domain. Moreover, ZmPAO ectopic expression in the cell wall of transgenic tobacco (Nicotiana tabacum) plants strongly enhanced lignosuberization along the wound periderm, providing evidence for a causal relationship between PAO and peroxidase-mediated events during wound healing.
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PMID:Involvement of polyamine oxidase in wound healing. 1799 45


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