@article {2307, title = {Reduction of ascorbate free radical by the plasma membrane of synaptic terminals from rat brain}, journal = {Arch Biochem Biophys}, volume = {469}, number = {2}, year = {2008}, note = {
1096-0384 (Electronic)0003-9861 (Linking)Journal ArticleResearch Support, Non-U.S. Gov{\textquoteright}t
}, month = {Jan 15}, pages = {243-54}, abstract = {Synaptic plasma membranes (SPMV) decrease the steady state ascorbate free radical (AFR) concentration of 1mM ascorbate in phosphate/EDTA buffer (pH 7), due to AFR recycling by redox coupling between ascorbate and the ubiquinone content of these membranes. In the presence of NADH, but not NADPH, SPMV catalyse a rapid recycling of AFR which further lower the AFR concentration below 0.05 microM. These results correlate with the nearly 10-fold higher NADH oxidase over NADPH oxidase activity of SPMV. SPMV has NADH-dependent coenzyme Q reductase activity. In the presence of ascorbate the stimulation of the NADH oxidase activity of SPMV by coenzyme Q(1) and cytochrome c can be accounted for by the increase of the AFR concentration generated by the redox pairs ascorbate/coenzyme Q(1) and ascorbate/cytochrome c. The NADH:AFR reductase activity makes a major contribution to the NADH oxidase activity of SPMV and decreases the steady-state AFR concentration well below the micromolar concentration range.
}, keywords = {*Free Radicals, Animals, Ascorbic Acid/*metabolism, Biochemistry/*methods, Brain/*metabolism, Cell Membrane/*metabolism, Cytochromes c/metabolism, Edetic Acid/chemistry, NADPH Oxidase/metabolism, Oxidation-Reduction, Rats, Synapses/*metabolism, Ubiquinone/chemistry}, url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve\&db=PubMed\&dopt=Citation\&list_uids=17963686 }, author = {Samhan-Arias, A. K. and Duarte, R. O. and Martin-Romero, F. J. and Moura, J. J. and Gutierrez-Merino, C.} }