Metabolic Processes in Cytoplasmic Particles of the Avocado Fruit. IV. Ripening and the Supernatant Fraction.

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Abstract
The oxidative and phosphorylative activities of cytoplasmic particles isolated from the avocado fruit were studied in relation to the process of ripening and senescence. The oxidation rates of [alpha]-ketoglutarate and malate were markedly reduced at the climacteric peak, while the P/O ratios tended to be high. The presence of dinitrophenol had little or no effect on the phosphorylative efficiency of the particles at the peak, though it did lower the P/O ratios at the earlier stages of ripening. The loss of oxidative activity of the a-ketoglutarate and pyruvate systems could be restored substantially by the addition of deproteinized supernatant fraction from ripe fruit. This solution exerted no influence on citrate and succinate oxidations, but with a-ketoglutarate its action was directly related to the stage of ripeness along the climacteric curve. The supernatant fraction exerted greatest effect when supplemented with adenylate and Coenzyme A. The idea was advanced that the role of this fraction was centered around the substrate level reactions of oxidative decarboxylation. The relation of this study to the "Uncoupling" theory of fruit ripening is discussed.