| Peroxidative oxidation of leuco-dichlorofluorescein by prostaglandin H synthase in prostaglandin biosynthesis from polyunsaturated fatty acids. | |
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MedLine Citation:
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PMID: 8555252 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Prostaglandin H synthase can oxidize arachidonic acid with leuco-dichlorofluorescein as reducing cosubstrate. Addition of 0.5 mM phenol increases the oxidation of leuco-dichlorofluorescein to dichlorofluorescein 5-fold, probably by acting as a cyclic intermediate in the oxidation. Tetramethyl-p-phenylenediamine is also oxidized as cosubstrate. Its oxidation is not influenced by phenol. A stoichiometry of close to one mole of tetramethyl-p-phenylenediamine or leuco-dichlorofluorescein consumed per mole of arachidonic acid was found in the initial phase of the reaction. In the presence of phenol + leuco-dichlorofluorescein, the oxidation rate of arachidonic acid is about 40% lower than with phenol alone as cosubstrate. Since dichlorofluorescein has a molar extinction coefficient of 91 . 10(3) at 502 nm, the oxidation of less than 1 microM leuco-dichlorofluorescein can be detected spectrophotometrically. The rate of extinction change with leuco-dichlorofluorescein (at 502 nm) is about 4-fold more rapid than with tetramethyl-p-phenylenediamine (at 611 nm). With this spectrophotometric assay we have confirmed that arachidonic acid, linolenic acid, adrenic acid, gamma-linolenic acid, eicosapentaenoic acid, are substrates for prostaglandin H synthase with decreasing reaction rates in the mentioned order. The same order of reaction rates were found when oxygen consumption was measured. The assay also shows that docosahexaenoic acid is substrate for the enzyme. The reaction rate of the enzyme evidently is decreased both by a n-3 double bond and by deviation from a 20 carbon chain length of the fatty acid substrate. |
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Authors:
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L N Larsen; E Dahl; J Bremer |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 1299 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 1996 Jan |
Date Detail:
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Created Date: 1996-02-26 Completed Date: 1996-02-26 Revised Date: 2005-11-17 |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 47-53 Citation Subset: IM |
Affiliation:
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Institute of Medical Biochemistry, University of Oslo, Norway. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cyclooxygenase Inhibitors / pharmacology Fatty Acids, Unsaturated / metabolism* Fluoresceins / chemistry* Horseradish Peroxidase Hydrogen Peroxide Hydrogen-Ion Concentration Indomethacin / pharmacology Male Oxidation-Reduction Phenol Phenols / pharmacology Prostaglandin-Endoperoxide Synthases / chemistry, metabolism* Prostaglandins / biosynthesis* Serum Albumin, Bovine / pharmacology Sheep Spectrophotometry Substrate Specificity |
| Chemical | |
Reg. No./Substance:
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0/Cyclooxygenase Inhibitors; 0/Fatty Acids, Unsaturated; 0/Fluoresceins; 0/Phenols; 0/Prostaglandins; 0/Serum Albumin, Bovine; 108-95-2/Phenol; 2044-85-1/diacetyldichlorofluorescein; 53-86-1/Indomethacin; 7722-84-1/Hydrogen Peroxide; EC 1.11.1.-/Horseradish Peroxidase; EC 1.14.99.1/Prostaglandin-Endoperoxide Synthases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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