Involvement of chlorophyllase in chlorophyll metabolism in olive varieties with high and low chlorophyll content.
Olive fruits of the Arbequina variety are differentiated from those of Hojiblanca and Picual by the differing presence of 132-OH-chlorophyll a and of dephytylated chlorophyll derivatives during the life cycle of the fruit. During the fruit growth stage, which coincides with chlorophyll synthesis, chlorophyllase (EC: 3.1.1.14) is present in the three varieties but only yields chlorophyllides in Arbequina. The presence of oxidized catabolites of chlorophyll a in fruits of the Arbequina variety during this same period confirms the activity of oxidative enzyme systems. The low synthesis of chlorophylls in the fruits of the Arbequina variety is associated with the fact that, during the natural biosynthetic turnover, the catabolic pathway is more potentiated than the anabolic one. In the ripening phase, in the Hojiblanca and Picual fruits, chlorophyllase activity was measured but the absence of chlorophyllides showed that this enzyme remains latent and that oxidative enzymes are the ones taking part in the chlorophyll disappearance. In the Arbequina variety, both chlorophyllase and oxidative enzymes are responsible for the chlorophyll degradation.
Roca
María
M
Departamento de Biotecnología de Alimentos, Instituto de la Grasa, CSIC, Avenida. Padre García Tejero, 4, Sevilla 41012, Spain.
Mínguez-Mosquera
María Isabel
MI