HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wakefield, L. M. Articles by Radda, G. K. Search for Related Content PubMed PubMed Citation Articles by Wakefield, L. M. Articles by Radda, G. K. Social Bookmarking                      What's this?

J. Biol. Chem., Vol. 261, Issue 21, 9746-9752, Jul, 1986

Electron transfer across the chromaffin granule membrane. Use of EPR to demonstrate reduction of intravesicular ascorbate radical by the extravesicular mitochondrial NADH:ascorbate radical oxidoreductase

LM Wakefield, AE Cass and GK Radda

A two-compartment electron paramagnetic resonance system has been developed in which the membrane-impermeable spin probe Ni(en)2+3 is used to selectively eliminate the EPR signal from extravesicular ascorbate radical, such that radicals in intra- and extravesicular compartments can be distinguished. Using this system, we have shown that an increase in ascorbate radical in the extravesicular medium is reflected by an increase in ascorbate radical within resealed chromaffin granule ghosts containing trapped ascorbate but has no effect on radical concentrations inside liposomes containing ascorbate. This indicates that the chromaffin granule membrane contains a component, not present in liposomes, that allows equilibration between the intra- and extravesicular ascorbate/ascorbate radical couples. This component is probably cytochrome b561. We further show that activation of the mitochondrial NADH:ascorbate radical oxidoreductase in the extravesicular medium causes a decrease in intravesicular ascorbate radical in chromaffin granule ghosts but not in liposomes. These data provide direct experimental evidence for the hypothesis that the adrenal medullary mitochondrial NADH:ascorbate radical oxidoreductase could drive the re-reduction of ascorbate free radical generated inside the chromaffin granule by the turnover of dopamine beta-hydroxylase, without the ascorbate radical ever having to leave the granule.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. M. VanDuijn, K. Tijssen, J. VanSteveninck, P. J. A. Van den Broek, and J. Van der Zee Erythrocytes Reduce Extracellular Ascorbate Free Radicals Using Intracellular Ascorbate as an Electron Donor J. Biol. Chem., September 1, 2000; 275(36): 27720 - 27725. [Abstract] [Full Text] [PDF]