| The reaction of coumarins with horseradish peroxidase. | |
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MedLine Citation:
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PMID: 16659024 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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The peroxidase catalyzed oxidation of indole-3-acetate is inhibited by naturally occurring coumarins such as scopoletin. This inhibition is due to the preferential reactivity of the coumarins with the peroxidase compounds I, II, and III. In view of the possible growth regulatory role of coumarins in plants, the mechanism of oxidation of scopoletin by horse-radish peroxidase has been investigated.Peroxidase catalyzed coumarin oxidation requires either an electron donor and molecular oxygen or hydrogen peroxide. If peroxide is present, the reaction is mediated by peroxidase compound II which reacts rapidly and stoichiometrically with scopoletin. Different oxidation products are formed, depending on whether IAA or hydrogen peroxide promotes the reaction. A scopoletin-free radical intermediate has been isolated from the peroxide reaction mixture but was not detected in the peroxide-free system.When indole-3-acetate is the electron donor, reduced peroxidase combines with molecular oxygen to give peroxidase compound III. Added scopoletin is cooxidized with indole-3-acetate. Compared to the scopoletin peroxidation, this reaction is slower and yields fewer coumarin oxidation products. The differences observed between the two scopoletin oxidation pathways reflect: (a) the competition between indole-3-acetate and scopoletin for peroxidase compounds; (b) the lower reactivity of scopoletin with peroxidase compound III compared with peroxidase compound II. The peroxide-promoted reaction is eliminated by catalase, while the indole-3-acetate initiated oxidation is not affected by excess quantities of either catalase or superoxidase dismutase. |
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Authors:
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R W Miller; J C Sirois; H Morita |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Plant physiology Volume: 55 ISSN: 0032-0889 ISO Abbreviation: Plant Physiol. Publication Date: 1975 Jan |
Date Detail:
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Created Date: 2010-06-29 Completed Date: 2010-06-29 Revised Date: 2010-09-14 |
Medline Journal Info:
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Nlm Unique ID: 0401224 Medline TA: Plant Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 35-41 Citation Subset: - |
Affiliation:
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Chemistry and Biology Research Institute and the Soil Research Institute, Research Branch, Agriculture Canada, Ottawa KIA OC6, Ontario, Canada. |
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