Ethylene formation from 1-aminocyclopropane-1-carboxylic acid in plant mitochondria

AbstractMitochondria isolated from apical parts of etiolated pea seedlings convert ACC to ethylene. This conversion is heat-sensitive and largely enhanced when the intact mitochondria are sonicated or when the ionophore nigericin is added to the reaction medium. When the sonicated submitochondiral particles are spun down, almost all of the activity is recovered in the pellet. The results suggest that the ethylene-formation activity is associated with the inner mitochondrial membrane and that transport of ACC into the mitochondrial membrane is a rate limiting step for the reaction. The mechanism of ACC transport across the mitochondrial membrane is discussed

Conversion of 1-aminocyclopropane-1-carboxylic acid to ethylene in submitochondrial particles isolated from plants Characterization of the system

AbstractConversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene was studied in submitochondrial particles (SMP) which were prepared by sonication of the mitochondrial fraction isolated from 7-day-old etiolated pea (Pisum sativum var. Kelvedon Wonder) seedlings. The reaction was enhanced by the addition of Mn2+ and had a maximal rate at pH 8.0. Conversion of ACC to ethylene was inhibited under anaerobic conditions and by the addition of KCN, EDTA, NaN3, n-propyl gallate and CoCl2. Addition of the uncouplers 2,4-DNP, CCCP and FCCP, however, did not inhibit the reaction. Structural analogs of ACC inhibited ACC conversion to enthylene by SMP. The structural analog of methionine, α-keto-γ-methylthiobutyric acid (KMB), was converted to ethylene by SMP at a rate which was only about 2% that of ACC conversion to ethylene