Document Detail

Semidehydroascorbic acid as an intermediate in norepinephrine biosynthesis in chromaffin granules.
MedLine Citation:
PMID:  1649168     Owner:  NLM     Status:  MEDLINE    
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.
K R Dhariwal; C D Black; M Levine
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  266     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1991 Jul 
Date Detail:
Created Date:  1991-08-19     Completed Date:  1991-08-19     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  12908-14     Citation Subset:  IM    
Laboratory of Cell Biology and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
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MeSH Terms
Adrenal Medulla / metabolism*
Chromaffin Granules / metabolism*
Dehydroascorbic Acid / analogs & derivatives*,  metabolism
Dithiothreitol / pharmacology
Ditiocarb / pharmacology
Electron Spin Resonance Spectroscopy
Electron Transport
Intracellular Membranes / metabolism
Models, Biological
Norepinephrine / biosynthesis*
Reg. No./Substance:
147-84-2/Ditiocarb; 3483-12-3/Dithiothreitol; 490-83-5/Dehydroascorbic Acid; 51-41-2/Norepinephrine; 6730-29-6/semidehydroascorbic acid

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