Comparison of Mitochondria from Tomato Fruits at Various Stages of Ripeness

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Abstract
Mitochondria were isolated from tomato fruits which were at the mature green, climacteric, and postclimacteric stages of ripeness. Ripening was accompanied by a decline in the ratio of mitochondria] protein to soluble protein and a progressive decline in capacity of mitochondria to oxidize malate and pyruvate. Uncoupling of oxidative phosphorylation did not occur during ripening, and P/O ratios were 2.0 - 2.4. Respiration of postclimacteric mitochondria was inhibited 63% by isolation at pH 6.5 compared to ph 7.5. Mature green preparations were not significantly affected by pH of isolation. Thus, the decline in mitochondrial oxidative capacity during ripening may be due to the appearance of an inhibitor which is partially removed from ripe mitochondria isolated at the higher pH.