Analysis of NADP-malic enzyme from peach during development, ripening and after heat treatment

J BORSANI; C BUDDE; BUSTAMANTE C.; MARIA FABIANA DRINCOVICH; LARA, MV; ANDREO, CARLOS S

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

The predominant organic acids in peach fruit are malic and citric acids, which are important attributes of the fruit flavor and whose proportions vary depending on the cultivar. Malic enzymes (MEs) catalyze the oxidative decarboxylation of L-malate, producing pyruvate, CO2, and NADPH in the presence of a divalent cation. This enzyme is widely distributed in nature due to the participation of the reaction products in a large number of metabolic pathways. The aim of this study was to characterize the different isoforms of NADP-ME from Prunus persica. Three different enzymes were identified. In silico studies indicated that two of them might be cytosolic (EMP1: ppa003214; EMP3: ppa003210) and EMP2: ppa002714 would be targeted to plastids. Real time RT-PCR studies and activity assays showed that NADP-MEs from peach are differentially expressed during development and ripening of the fruit. On the other hand, the effect on MEs of a postharvest heat treatment (HT, 39ºC for 3 days, which was proved to be effective in protecting peach fruit against chilling injury) was also analyzed, showing that the expression and activity of MEs was diminished as a consequence of the HT. Additionally, EMP1, was expressed in Escherichia coli, purified and its kinetic parameters analyzed, display particular properties in relation to other already characterized MEs