TY - JOUR
T1 - Reduction of ascorbate free radical by the plasma membrane of synaptic terminals from rat brain
AU - Samhan-Arias, Alejandro K.
AU - Duarte, Rui O.
AU - Martín-Romero, Francisco Javier
AU - Moura, José J. G.
AU - Gutiérrez-Merino, Carlos
N1 - Supported by Grant SAF2003-08275 of the Spanish Ministerio de Educación y Ciencia. Alejandro K. Samhan-Arias is a recipient of a pre-doctoral fellowship of the Junta de Extremadura.
PY - 2008/1/15
Y1 - 2008/1/15
N2 - Synaptic plasma membranes (SPMV) decrease the steady state ascorbate free radical (AFR) concentration of 1 mM 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 μM. 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 Q1 and cytochrome c can be accounted for by the increase of the AFR concentration generated by the redox pairs ascorbate/coenzyme Q1 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.
AB - Synaptic plasma membranes (SPMV) decrease the steady state ascorbate free radical (AFR) concentration of 1 mM 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 μM. 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 Q1 and cytochrome c can be accounted for by the increase of the AFR concentration generated by the redox pairs ascorbate/coenzyme Q1 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.
KW - Ascorbate
KW - Ascorbate free radical
KW - Coenzyme Q
KW - Cytochrome c
KW - NADH oxidase
KW - Synaptic plasma membranes
UR - http://www.scopus.com/inward/record.url?scp=37349000240&partnerID=8YFLogxK
U2 - 10.1016/j.abb.2007.10.004
DO - 10.1016/j.abb.2007.10.004
M3 - Article
C2 - 17963686
AN - SCOPUS:37349000240
SN - 0003-9861
VL - 469
SP - 243
EP - 254
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 2
ER -