The Relationship Between Electron Flux and the Redox Poise of the Quinone Pool in Plant Mitochondria. Interplay Between Quinol-Oxidizing and Quinone-Reducing Pathways

We have studied the relation between rate and Q redox state for both quinol-oxidizing and quinone-reducing pathways under a variety of metabolic conditions including state 3, state 4, in the presence of myxothiazol, and benzohydroxamate

Corrine W. M. Bergen; Anneke M. Wagner; Klaas Krab; Anthony L. Moore

2005

Key concepts

Scholarcy highlights

  • The dependence of electron flux through quinone-reducing and quinol-oxidizing pathways on the redox state of the ubiquinone pool was investigated in plant mitochondria isolated from potato
  • We have determined the redox state of the Q pool with two different methods, the Q-electrode and Q-extraction techniques
  • Results from the two techniques agree well, in all tissues tested an inactive pool of QH2 was detected by the extraction technique that was not observed with the electrode
  • An advantage of the extraction method is that it permits determination of the Q redox state in the presence of substances that interfere with the Q-electrode, such as benzohydroxamate and NADH
  • We have studied the relation between rate and Q redox state for both quinol-oxidizing and quinone-reducing pathways under a variety of metabolic conditions including state 3, state 4, in the presence of myxothiazol, and benzohydroxamate
  • It is suggested that the oxidation of cytoplasmic NADH in vivo uses the cyanide-resistant pathway more than the pathway involving the oxidation of succinate
  • It is shown that titrations with inhibitors of the alternative oxidase cannot be used to demonstrate a pure overflow function of the alternative oxidase

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