Pyruvate metabolism during maturation of oranges citrus sinensis cultivar hamlin
Roe, B.; Davis, P.L.; Bruemmer, J.H.
Phytochemistry 23(4): 713-718
The roles of the pyruvate decarboxylation pathway and TCA [tricarboxylic acid] metabolic cycle in activation of anaerobic metabolism in ripening 'Hamlin' oranges were investigated. Oranges were harvested weekly Oct.-Feb. during the 1980-81 and 1981-82 growing season. Juice vesicles from each weekly sample were assayed for pyruvate decarboxylase, alcohol dehydrogenase, malic enzyme, phosphoenolpyruvate carboxylase, malate dehydrogenase, citrate synthase, isocitrate dehydrogenase and cytochrome oxidase. Also, juice was assayed for ethanol, acetaldehyde, pyruvate, oxalacetate, malate and citrate. In Dec. when ethanol accumulated rapidly in the fruit, pyruvate decarboxylase and alcohol dehydrogenase increased markedly. During the same month, the pyruvate level declined, suggesting that the increases in enzyme levels activated the conversion of pyruvate to ethanol.