CHANGES IN THE ACTIVITY OF PHOSPHOENOLPYRUVATE CARBOXYLATING ENZYMES IN GERMINATING YELLOW LUPIN SEEDS

The rate of phosphoenolpyruvate carboxylation by extracts from germina ting lupin seeds was measured through the (HCO3)-C-14 fixation. PEP ca rboxylation in seed axes increased during their imbibition, mainly as a result of the increase in the activity Of PEP carboxylase [EC 4.1.1. 31]. However, the activity of PEP carboxykinase [EC 4.1. 1.38],present during the first 3 hours of imbibition, as well as the activity of PE P-carboxykinase [EC 4.1.1.49], after 24 hours of imbibition, have also been shown. Possible physiological role of the changes in the activit y of PEP carboxylases during lupin seeds germination is discussed.