Superoxide and hydrogen peroxide productions by NO-inhibited complex Ⅲ  

作　　者：DARIO E.IGLESIAS SILVINA S.BOMBICINO ALBERTO BOVERIS LAURA B.VALDEZ 

机构地区：[1]不详

出　　处：《BIOCELL》2016年第1期26-29,共4页生物细胞（英文）

基　　金：supported by research grants from the University of Buenos Aires(UBACYT 200-201-101-00140 and 200-201-301-00731);Agencia Nacional de Promoción Científica y Tecnológica(PICT 2012-0964);Consejo Nacional de Investigaciones Científicas y Técnicas(PIP 112-201-101-00444).

摘　　要：Complex Ⅲ plays a central role in the mitochondrial respiratory chain transferring electrons from ubiquinol to cytochrome c and pumping protons to the intermembrane space,contributing to the protonmotive force.Furthermore,complex Ⅲ can act as a source of O_(2^(·-))in the presence of ubiquinol and antimycin,an expermiental condition in which the oxidation of the cytochrome b hemes is blocked.The O_(2^(·-))dismutation catalyzed by superoxide dismutase produces H2O2,a known second messenger in redox signalling.Results from our laboratory have shown that NO,released from GSNO or from SPER-NO or generated by mtNOS,inhibits electron transfer at ubiquinone-cytochrome b area producing antimycin-like effects.Thus,both antimycin-and NO-inhibited complex Ⅲ showed a high content of cytochromes b in the reduced state(79 and 71%,respectively)and an enhancement in the ubisemiquinone EPR signal at g=1.99(42 and 35%,respectively).As consequence,O_(2^(·-))and H2O2 productions were increased,being the O_(2^(·-))/H_(2)O_(2) ratio equal to 1.98 in accordance with the stoichiometry of the O_(2^(·-))disproportionation.The interruption of the oxidation of cytochromes b by NO leads to an enhancement of the steady-state concentration of UQH·,allowing cytochrome bc1 complex to act as a source of reactive oxygen species in physiological conditions.

关 键 词：S-nitrosoglutathione(GSNO) spermine-NONOate(SPER-NO) electron paramagnetic resonance(EPR) ubisemiquinone 

分 类 号：O64[理学—物理化学]