Oxidative phosphorylation supported by an alternative respiratory pathway in mitochondria from Euglena

被引:24
作者
Moreno-Sánchez, R
Covián, R
Jasso-Chávez, R
Rodríguez-Enríquez, S
Pacheco-Moisés, F
Torres-Márquez, ME
机构
[1] Inst Nacl Cardiol, Dept Bioquim, Col Secc 16, Mexico City 14080, DF, Mexico
[2] Univ Nacl Autonoma Mexico, Fac Med, Dept Bioquim, Mexico City 04510, DF, Mexico
来源
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS | 2000年 / 1457卷 / 03期
关键词
ATP synthesis; antimycin; cyanide-resistant respiration; Euglena;
D O I
10.1016/S0005-2728(00)00102-X
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The effect of antimycin, myxothiazol, 2-heytyl-4-hydroxyquinoline-N-oxide, stigmatellin and cyanide on respiration, ATP synthesis, cytochrome c reductase, and membrane potential in mitochondria isolated from dark-grown Euglena cells was determined. With L-lactate as substrate, ATP synthesis was partially inhibited by antimycin, but the other four inhibitors completely abolished the process. Cyanide also inhibited the antimycin-resistant ATP synthesis. Membrane potential was collapsed (< 60 mV) by cyanide and stigmatellin. However, in the presence of antimycin, a H+ gradient (> 60 mV) that sufficed to drive ATP synthesis remained. Cytochrome c reductase, with L-lactate as donor, was diminished by antimycin and myxothiazol. Cytochrome bc(1) complex activity was fully inhibited by antimycin. but it was resistant to myxothiazol. Stigmatellin inhibited both L-lactate-dependent cytochrome c reductase and cytochrome bc(1) complex activities. Respiration was partially inhibited by the five inhibitors. The cyanide-resistant respiration was strongly inhibited by diphenylamine, n-propyl-gallate, salicylhydroxamic acid and disulfiram. Based on these results, a model of the respiratory chain of Euglena mitochondria is proposed, in which a quinol-cytochrome c oxidoreductase resistant to antimycin, and a quinol oxidase resistant to antimycin and cyanide are included. (C) 2000 Elsevier Science B.V. All rights reserved.
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页码:200 / 210
页数:11
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