| Literature DB >> 17963686 |
Alejandro K Samhan-Arias1, Rui O Duarte, Francisco Javier Martín-Romero, Jose J G Moura, Carlos Gutiérrez-Merino.
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.Entities:
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Year: 2007 PMID： 17963686 DOI： 10.1016/j.abb.2007.10.004
Source DB: PubMed Journal: Arch Biochem Biophys ISSN： 0003-9861 Impact factor: 4.013