The final step in ethylene biosynthesis is catalyzed by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) oxidase. ACC oxidase was extracted from mung bean hypocotyls and its biochemical characteristics were determined. In vitro ACC oxidase activity required ascorbate and Fe2+, and was enhanced by sodium bicarbonate. Maximum specific activity (approximately 20 nl ethylene h-1 mg protein-1) was obtained in an assay medium containing 100 mM MOPS (pH 7.5), 25 μM FeSO4, 6 mM sodium ascorbate, 1 mM ACC, 5 mM sodium bicarbonate and 10% glycerol. The apparent Km for ACC was 80 ± 3 μM. Pretreating mung bean hypocotyls with ethylene increased in vitro ACC oxidase activity twofold. ACC oxidase activity was strongly inhibited by metal ions such as Co2+, Cu2+, Zn2+, and Mn2+, and by salicylic acid. Inactivation of ACC oxidase by salicylic acid could be overcome by increasing the Fe2+ concentration of the assay medium. The possible mode of inhibition of ACC oxidase activity by salicylic acid is discussed.
|Number of pages||7|
|Journal||Journal of Biochemistry and Molecular Biology|
|Publication status||Published - 1998 Jan 31|
All Science Journal Classification (ASJC) codes
- Molecular Biology