Oxidative phosphorylation supported by an alternative respiratory pathway in mitochondria from Euglena
Por:
Moreno-Sánchez R., Covián R., Jasso-Chávez R., Rodríguez-Enríquez S., Pacheco-Moisés F., Torres-Márquez M.E.
Publicada:
1 ene 2000
Resumen:
The effect of antimycin, myxothiazol, 2-heptyl-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 bc1 complex activity was fully inhibited by antimycin, but it was resistant to myxothiazol. Stigmatellin inhibited both L-lactate-dependent cytochrome c reductase and cytochrome bc1 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. Copyright (C) 2000 Elsevier Science B.V.
Filiaciones:
Moreno-Sánchez R.:
Departamento de Bioquímica, Inst. Nac. Cardiol., Juan B., Mexico, Mexico
Covián R.:
Departamento de Bioquímica, Inst. Nac. Cardiol., Juan B., Mexico, Mexico
Jasso-Chávez R.:
Departamento de Bioquímica, Fac. Med., Univ. Nac. Auton. M., Mexico, Mexico
Rodríguez-Enríquez S.:
Departamento de Bioquímica, Inst. Nac. Cardiol., Juan B., Mexico, Mexico
Pacheco-Moisés F.:
Departamento de Bioquímica, Inst. Nac. Cardiol., Juan B., Mexico, Mexico
Torres-Márquez M.E.:
Departamento de Bioquímica, Fac. Med., Univ. Nac. Auton. M., Mexico, Mexico
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