Mitochondrial enzymes in mango fruit during ripening

Abstract Mitochondria isolated from immature (developing), mature (unripe), and ripe mango pulp actively oxidized the intermediates of the Krebs cycle. The oxidation of citrate, oxoglutarate, succinate and malate by both unripe and ripe fruit mitochondria was several fold greater than that by mitochondria from immature fruit. The levels of malic dehydrogenase and succinic dehydrogenase increased with the onset of ripening, whereas the level of citrate synthase increased several fold on maturation but decreased six-fold on ripening. Isocitrate dehydrogenase and malic enzyme were very high in the immature fruit but after a sudden decrease in the matured fruit showed a considerable rise thereafter. The ratio of the activities of isocitrate lyase to isocitrate dehydrogenase is considerably higher in the immature fruit and greatest in the unripe (mature) fruit. This, together with a higher concentration of glyoxylate at these stages, indicate the operation of the glyoxylate bypass. Oxidized and reduced forms of pyridine nucleotides were estimated.