Studies on the metabolism of free amino acids during maturation and ripening of tomato fruits

Glutamic acid decarboxylase in Fukuju No. 2 tomato fruits was easily extracted with M/15 phosphate buffer and showed the highest activity between pH 5.5 and 5.6. The decarboxylase activity was very high in immature tomato fruits and decreased during maturation. With ripening at 20°C the enzyme activity also decreased, but after 27 days in the storage at 6°C it was high. When tomato fruits were irradiated with 250 and 1, 000 Krad at the stage of breaker, the activities of the decarboxylase in irradiated fruits lowered markedly immediately after irradiation in comparison with those in unirradiated fruits. Then they were recognized to recover temporarily after 2 to 5 days.Glutamic acid dehydrogenase was found in tomato fruits. The activity of the dehydrogenase was higher in immature fruits than in mature ones.