The Interaction of Energy and Electron Transfer Reactions in Mitochondria

Abstract

In the preceding paper (l), we demonstrate a succinate-linked reduction of pyridine nucleotide that is sensitive to the concentration of high energy intermediates in the mitochondria and, in a subsequent paper (2), a pathway of electron transfer that suggests that the energy required in this reaction is expended through carriers of the respiratory chain in an energy-linked reversal of electron transfer. Although only a portion of the electron transfer from the substrate follows this reversed pathway (I), it is important to determine whether the reversal is a general phenomenon or is limited to the branch of the respiratory chain that leads to succinate-linked pyridine nucleotide reduction. To this end, we describe here adenosine 5’-triphosphate-linked oxidation of cytochromes and flavoprotein and reduction of pyridine nucleotide in pigeon heart, rat liver, and rat brain mitochondria and in particles from digitonin-treated rat liver and pigeon heart mitochondria.