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

BORSANI, JULIA; BUDDE, CLAUDIO OLAF; BUSTAMANTE, CLAUDIA; DRINCOVICH, MARÍA FABIANA; LARA, MARÍA VALERIA; ANDREO, CARLOS S.

Potrero de los Funes

Congreso; XLVII Reunión Anual de SAIB; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The predominant organic acids in peach fruit are malic and citricacids, which are important attributes of the fruit flavor and whoseproportions vary depending on the cultivar. Malic enzymes (MEs)catalyze the oxidative decarboxylation of L-malate, producingpyruvate, CO , and NADPH in the presence of a divalent cation. 2This enzyme is widely distributed in nature due to the participationof the reaction products in a large number of metabolic pathways.The aim of this study was to characterize the different isoforms ofNADP-ME from Prunus persica. Three different enzymes wereidentified. In silico studies indicated that two of them might becytosolic (EMP1: ppa003214; EMP3: ppa003210) and EMP2:ppa002714 would be targeted to plastids. Real time RT-PCR studiesand activity assays showed that NADP-MEs from peach aredifferentially expressed during development and ripening of thefruit. On the other hand, the effect on MEs of a postharvest heattreatment (HT, 39ºC for 3 days, which was proved to be effective inprotecting peach fruit against chilling injury) was also analyzed,showing that the expression and activity of MEs was diminished asa consequence of the HT. Additionally, EMP1, was expressed inEscherichia coli, purified and its kinetic parameters analyzed,displaying particular properties in relation to other alreadycharacterized