Isolation of Active Subcellular Particles from Avocado Fruit at Various Stages of Ripeness

Abstract

MANY fruits, including the avocado, exhibit a marked increase in respiration during the ripening process which is known as the ‘climacteric rise’¹. An explanation of this phenomenon has been sought by investigating the oxidation and phosphorylation of cytoplasmic particles isolated from fruit at various points during the post-harvest life of the fruit. Particles have been isolated from avocados², apples³, tomatoes⁴, bananas⁵ and papayas⁶ which proved capable of oxidizing Krebs cycle acids. Only in the case of avocado fruit at the climacteric peak² has it been shown conclusively that the particles were able to exhibit the phenomenon of ‘respiratory control’⁷. This communication describes modifications to a method given by Wiskich et al.² by which particles that show respiratory control and coupled phosphorylation may be isolated from avocado fruit at all stages of ripeness. The revised method has also been successfully applied to sweet potatoes and tomato fruit.