Activity of 1-aminocyclopropane-l-carboxylate (ACC) oxidase (ethylene-forming enzyme) in the pulp and peel of ripening bananas

Abstract

SummaryActivity of 1-aminocyclopropane-l-carboxylate (ACC) oxidase (previously known as the ethylene-forming enzyme, EFE) in the pulp and peel of ripening bananas has been stud-ied in vitro, using tissue discs, and in vitro. The enzyme extracted from both pulp and peel resembles ACC oxidases from a variety of other fruits in its requirement for ascorbate, Fe2+ and CO2, when assayed in vitro, and in its Mr of about 41,000. When the enzyme was assayed in vivo, ascorbate, Fe2+ and CO2 stimulated activity in pulp tissue during the later stages of ripening. By contrast, the enzyme assayed in vivo from peel tissue was not stimulated by these factors. Changes in enzyme activity during ripening did not support a role for the pulp as a trigger for the ripening of the whole fruit.