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dc.contributorWichita State University. Department of Chemistryen_US
dc.contributor.authorWimalasena, Kandategeen_US
dc.contributor.authorWimalasena, D. Shyamalien_US
dc.identifierGM 45026en_US
dc.identifier.citationThe Journal of biological chemistry. 1995 Nov 17; 270(46): 27516-24.en_US
dc.descriptionAccess full text below in the Files in this item section.en_US
dc.description.abstractThe role of internal and external reductants in the dopamine beta-monooxygenase (D beta M)-catalyzed conversion of dopamine to norepinephrine has been investigated in resealed chromaffin granule ghosts. The rate of norepinephrine production was not affected by the exclusion of internal ascorbate. The omission of ascorbate from the external medium drastically reduced the norepinephrine production without affecting the net rate of dopamine uptake. In the presence of the external reductant, the internal ascorbate levels were constant throughout the incubation period. The rate of norepinephrine production was not affected when ghosts were resealed to contain the D beta M reduction site inhibitor, imino-D-glucoascorbate. Ghosts incubated with external imino-D-glucoascorbate reduced the norepinephrine production. The weak D beta M reductant, 6-amino-L-ascorbic acid, was found to be a good external reductant for granule ghosts. The outcome of the above experiments was not altered when dopamine was replaced with the reductively inactive D beta M substrate, tyramine. These results and the known topology of membrane-bound D beta M disfavor the direct reduction of the enzyme by the external reductant. Our observations are consistent with the hypothesis that external ascorbate is the sole source of reducing equivalents for D beta M monooxygenation and that internal soluble ascorbate (or dopamine) may not directly reduce or mediate the reduction of membrane-bound D beta M in resealed granule ghosts.en_US
dc.description.sponsorshipNIGMS NIH HHSen_US
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen_US
dc.relation.ispartofseriesThe Journal of biological chemistryen_US
dc.relation.ispartofseriesJ. Biol. Chem.en_US
dc.subjectComparative Studyen_US
dc.subjectResearch Support, U.S. Gov't, P.H.S.en_US
dc.subject.lcshAscorbic Acid/metabolismen_US
dc.subject.lcshAscorbic Acid/pharmacologyen_US
dc.subject.meshAdenosine Triphosphate/metabolismen_US
dc.subject.meshAdrenal Medulla/enzymologyen_US
dc.subject.meshAscorbic Acid/analogs & derivativesen_US
dc.subject.meshCell Fractionation/methodsen_US
dc.subject.meshChromaffin Granules/enzymologyen_US
dc.subject.meshDopamine beta-Hydroxylase/metabolismen_US
dc.subject.meshIntracellular Membranes/enzymologyen_US
dc.titleThe reduction of membrane-bound dopamine beta-monooxygenase in resealed chromaffin granule ghosts. Is intragranular ascorbic acid a mediator for extragranular reducing equivalents?en_US
dc.coverage.spacialUnited Statesen_US
dc.description.versionpeer revieweden_US
dc.rights.holderCopyright © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.en_US

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