| Semidehydroascorbic acid as an intermediate in norepinephrine biosynthesis in chromaffin granules. | |
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MedLine Citation:
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PMID: 1649168 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We investigated whether semidehydroascorbic acid was an intermediate in norepinephrine synthesis in chromaffin granules and in electron transfer across the chromaffin granule membrane. Semidehydroascorbic acid was measured in intact granules by electron spin resonance. In the presence of intragranular but not extragranular ascorbic acid, semidehydroascorbic acid was formed within granules in direct relationship to dopamine beta-monooxygenase activity. However, semidehydroascorbic acid was not generated when granules were incubated with epinephrine instead of the substrate dopamine, with dopamine beta-monooxygenase inhibitors, without oxygen, and when intragranular ascorbic acid was depleted. Experiments using the impermeant paramagnetic broadening agents [K3 [Cr(C2O4)3].3H2O] and Ni(en)3(NO3)2 provided further evidence that semidehydroascorbic acid was generated only within granules. We also investigated semidehydroascorbic acid formation in the presence of intragranular and extragranular ascorbic acid. Under these conditions, semidehydroascorbic acid was formed on both sides of the granule membrane, and formation was coupled to dopamine beta-monooxygenase activity. These data indicate that dopamine beta-monooxygenase is reduced by single electron transfer from intragranular ascorbic acid, that transmembrane electron transfer occurs by single electron transfer, and that transmembrane electron transfer is directly coupled to formation of intragranular semidehydroascorbic acid via dopamine beta-monooxygenase activity. |
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Authors:
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K R Dhariwal; C D Black; M Levine |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 266 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 1991 Jul |
Date Detail:
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Created Date: 1991-08-19 Completed Date: 1991-08-19 Revised Date: 2003-11-14 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 12908-14 Citation Subset: IM |
Affiliation:
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Laboratory of Cell Biology and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenal Medulla
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metabolism* Animals Cattle Chromaffin Granules / metabolism* Dehydroascorbic Acid / analogs & derivatives*, metabolism Dithiothreitol / pharmacology Ditiocarb / pharmacology Electron Spin Resonance Spectroscopy Electron Transport Intracellular Membranes / metabolism Kinetics Models, Biological Norepinephrine / biosynthesis* |
| Chemical | |
Reg. No./Substance:
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147-84-2/Ditiocarb; 3483-12-3/Dithiothreitol; 490-83-5/Dehydroascorbic Acid; 51-41-2/Norepinephrine; 6730-29-6/semidehydroascorbic acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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