Oxidative activity of cytoplasmic particles of apples: Krebs cycle oxidations, oxidative phosphorylation, & cytochromes

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Abstract
Comparative studies were made of apple particles isolated from neutral and alkaline homogenates. Particles from neutral homogenates (pH 6.5-7.2) showed very little mitochondrial activity. However, those from homogenates of pH 8.4 to 8.6 gave highest rates of Krebs cycle oxidation, oxidative phosphorylation, and clearest cytochrome spectra. Particles from homogenates of pH 9.9 exhibited highest malate dehydrogenase activity. Rates of isocitrate dehydrogenase activity were the same in all these particles. Low temperature spectra (-195C) of the particles revealed absorption bands at 599 m[mu], 556 to 558 m[mu], 552 m[mu] and 548 to 549 m[mu]. These are tentatively identified as cytochromes a + a3, 2 cytochrome b''s and cytochrome c. The data are taken as presumptive evidence for the presence of mitochondria in apple pulp tissue.