Changes in the activities of malic enzyme, malate dehydrogenase, phosphopyruvate carboxylase and pyruvate decarboxylase during the development of a non-climacteric fruit (the grape)

Abstract

The activities of malic enzyme, pyruvate decarboxylase, phosphopyruvate carboxylase and malate dehydrogenase were determined at weekly intervals during the development of a fruit which does not show a climacteric rise in respiration (sultana grape berries). Unlike apples, which show large increases in activities of malic enzyme and pyruvate decarboxylase, grape berries did not have large consistent increases in activities of these enzymes during the period in which malic acid concentration decreased. Phosphopyruvate carboxylase activity which was high in very young berries, decreased to a low value at about the same time that net synthesis of malic acid ceased.