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)

Effect of IAA (10(-10)-10(-3) M) on photophosphorylation, NADP reduction and the oxygen exchange is investigated. It is shown that low concentrations of IAA (10(-10)-10(-7) M) increase the photophosphorylation reaction and the flow of electrones to NADP under the phosphorylation conditions in the chloroplasts, and their effect on the O2 exchange is not the same in different types of photophosphorylation. It is supposed that the effect of IAA on the photophosphorylation is connected with H292 metabolism in chloroplasts and with catalase and peroxidase functions.
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PMID:[Effect of IAA on the photophosphorylation of pea isolated chloroplasts]. 0 32

Peroxidase and indole acetic oxidase (IA oxidase) activities in seeds of Cicer arietinum L. were studied at 72 h of germination. Both activities behaved differently in relation to optimum pH, stability against temperature and time of storage of 4 degrees C. Disc electrophoresis on polyacrilamide gel showed the existence of five anionic and three cationic isoenzymes with peroxidase activity by using benzidine as substrate; three of the anionic isoenzymes and one cationic isoenzyme possessed a simultaneous IAA oxidase activity as well.
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PMID:Peroxidase and IAA oxidase in germinating seeds of Cicer arietinum L. 712 73

Tomato fruit (Lycopersicon esculentum Mill cv. Walters) peroxidase was purified to apparent homogeneity by a three step procedure: hydrophobic chromatography, DEAE Sephacel chromatography and semi-preparative electrophoresis. A purification of 71 fold and a yield of 52% relative to crude extract were obtained. The pure enzyme was brown in color and showed a molecular weight of 45,000 as estimated from SDS disc gel electrophoresis and gel filtration on Ultrogel AcA 34. The pH optimum of tomato peroxidase varied with substrate dyes used and the enzyme may have some hydrophobic properties near its active site. The optimum temperature was 35 degrees C for this enzyme, and IAA oxidase activity was evident in the presence of 2,4-dichlorophenol and manganese. The apparent KM for IAA was measured to be 0.24 mM.
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PMID:Preparation of a homogeneous tomato fruit peroxidase. 744 33

Cultures of C. pendulus were maintained on hormone free and hormone supplemented (NAA 1.0 mg/l and kinetin 0.5 mg/l) Murashige and Skoog medium. During the growth period, hormone free cultures had higher phenolic content, polyphenol oxidase activity and less protein content, peroxidase and IAA oxidase activity. Activity of all the three oxidising enzymes and phenolic content were high at 16 days growth. Total lipid content was higher (2.7-folds at 15 days) in hormone free cultures. Phospholipid content of both cultures was not markedly dissimilar except PC and DGDG contents. Thus it is evidenced that both the tissues were similar metabolically.
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PMID:Changes in phospholipids, fatty acids, oxidative enzymes, phenolics and protein levels during growth of normal and habituated tissues of Cocculus pendulus. 811 78

Indole-3-acetic acid (IAA) is a powerful plant growth regulator. The oxidative decarboxylation of IAA by plant peroxidases is thought to be a major degradation reaction involved in controlling the in vivo level of IAA. Horseradish peroxidase isoenzyme C and an anionic tobacco peroxidase isolated from transgenic Nicotiana sylvestris have been used in experiments in vitro designed to determine the mechanism of IAA oxidation. In particular, the initial reduction of ferric to ferrous enzyme, a key step in previously proposed mechanisms, has been investigated by rapid-scan stopped-flow spectrophotometry under strictly anaerobic conditions and at defined oxygen concentrations. The data provide the first evidence for a ternary complex comprising peroxidase, IAA and oxygen that is kinetically competent both at the initiation stage and during the catalytic cycle of IAA oxidation. A general scheme describing the oxidative cycles of both anionic and cationic peroxidases is proposed that includes native ferric enzyme and compound II as kinetically competent intermediates. For anionic peroxidases, addition of hydrogen peroxide switches on the oxidative cycle thereby promoting IAA oxidation. 2-Methyl-IAA is not a substrate of the oxidase reaction, suggesting a specific interaction between plant peroxidases and IAA.
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PMID:Mechanism of indole-3-acetic acid oxidation by plant peroxidases: anaerobic stopped-flow spectrophotometric studies on horseradish and tobacco peroxidases. 861 Nov 64

Peroxidase activity in neutrophils is higher than in thioglycollate macrophages, while in lymphocytes this enzyme activity is very low. Indole-3-acetic acid is oxidized by peroxidase and the role of this enzyme in the cytotoxic effect of the compound was evaluated by measuring oxygen consumption, light emission and cell death in neutrophils, macrophages and lymphocytes. The increase in light emission, oxygen consumption and rate of cell death in cells cultured in the presence of indole-3-acetic acid presented a direct correlation with the peroxidase activity of the cells as follows: neutrophils > thioglycollate macrophages > resident macrophages > lymphocytes. Indeed, in lymphocytes that possess very low peroxidase activity, indole-3-acetic acid did not result in an increase in light emission or oxygen consumption and it was not cytotoxic.
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PMID:Peroxidase activity may play a role in the cytotoxic effect of indole acetic acid. 906 8

Indol-3-yl acetic acid (IAA, auxin) is a plant hormone whose degradation is a key determinant of plant growth and development. The first evidence for skatolyl hydroperoxide formation during the plant peroxidase-catalysed degradation of IAA has been obtained by electrospray MS. Skatolyl hydroperoxide degrades predominantly non-enzymically to oxindol-3-yl carbinol but in part enzymically into indol-3-yl methanol via a peroxidase cycle in which IAA acts as an electron donor. Skatolyl hydroperoxide is degradable by catalase. Horseradish peroxidase isoenzyme C (HRP-C) and anionic tobacco peroxidase (TOP) exhibit differences in their mechanisms of reaction. The insensitivity of the HRP-C-catalysed reaction to catalase is ascribed to the formation of HRP-C Compound III at the initiation step and its subsequent role in radical propagation. This is in contrast with the TOP-catalysed process in which skatolyl hydroperoxide has a key role. Indol-3-yl aldehyde is produced not via the peroxidase cycle but by catalysis involving ferrous peroxidase. Because indol-3-yl aldehyde is one of the main IAA-derived products identified in planta, we conclude that ferrous peroxidases participate in IAA catalytic transformations in vivo. A general scheme for peroxidase-catalysed IAA oxidation is presented.
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PMID:Identification of skatolyl hydroperoxide and its role in the peroxidase-catalysed oxidation of indol-3-yl acetic acid. 963 83

Indole-3-acetic acid (IAA) can be oxidized via two mechanisms: a conventional hydrogen-peroxide-dependent pathway, and one that is hydrogen-peroxide-independent and requires oxygen. It has been shown here for the first time that only plant peroxidases are able to catalyse the reaction of IAA oxidation with molecular oxygen. Cytochrome c peroxidase (CcP), fungal peroxidases (manganese-dependent peroxidase, lignin peroxidase and Arthromyces ramosus peroxidase) and microperoxidase were essentially inactive towards IAA in the absence of added H2O2. An analysis of amino acid sequences allowed five structurally similar fragments to be identified in auxin-binding proteins and plant peroxidases. The corresponding fragments in CcP and fungal peroxidases showed no similarity with auxin-binding proteins. Five structurally similar fragments form a subdomain including the catalytic centre and two residues highly conserved among 'classical' plant peroxidases only, namely His-40 and Trp-117. The subdomain identified above with the two residues might be responsible for the oxidation of the physiological substrate of classical plant peroxidases, IAA.
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PMID:Oxidation of indole-3-acetic acid by dioxygen catalysed by plant peroxidases: specificity for the enzyme structure. 1035 40

Indole-3-acetic acid (IAA) and some derivatives can be oxidised by horseradish peroxidase (HRP) to cytotoxic species. Upon treatment with IAA/HRP, liposomes undergo lipid peroxidation, strand breaks and adducts are formed in supercoiled plasmid DNA, and mammalian cells in culture lose colony-forming ability. IAA is only toxic after oxidative decarboxylation; no effects are seen when IAA or HRP is incubated independently in these systems at equivalent concentrations. Toxicity is similar in both hamster fibroblasts and some human tumour cells. The effect of IAA/HRP is thought to be due in part to the formation of 3-methylene-2-oxindole, which may conjugate with DNA bases and protein thiols. Our hypothesis is that IAA/HRP could be used as the basis for targeted cancer therapy involving antibody-, polymer-, or gene-directed approaches. HRP can thus be targeted to a tumour allowing non-toxic IAA delivered systemically to be activated only in the tumour. Exposure to newly synthesised analogues of IAA shows a range of four orders of magnitude difference in cellular toxicity but no structure-activity relationships are apparent, in contrast to well-defined redox dependencies of oxidation by HRP intermediates or rates of decarboxylation of radical-cation intermediates.
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PMID:Oxidative activation of indole-3-acetic acids to cytotoxic species- a potential new role for plant auxins in cancer therapy. 1116 27

Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.
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PMID:Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays. 1153 38


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