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Effect of O_(2), ACC and CO_(2) concentration on the activity of partially purified ACC oxidase from papaya

Song Songquan, Yip Wing-Kin

The Key Laboratory of Gene Engineering of Ministry of Education,School of Life Sciences,Zhongshan University.Guangzhou 510275,Guangdong

Abstract

ACC oxidase has been purified 19.5-fold by using DEAE-Sepharose and Phenyl-Sepharose columns. The K_(m) value by ACC oxidase for O_(2) in ethylene production varied greatly depending on the ACC concentration, and decreased with increase of ACC levels. The K_(m) value for ACC also declined as oxygen concentration increased. The enzyme activity was dramatically increased by CO_(2), and the K_(m) value for O_(2) and for ACC increased with increase of CO_(2) concentration. Enzyme activities were obviously increased by Fe~(2+) and significantly inhibited by Co~(2+); and Fe~(2+) could antagonize the inhibotory role of Co~(2+). These kinetic data are consistent with the view that the catalytic role of ACC oxidase follows an ordered binding mechanism in which ACC oxidase binds first to O_(2) and then to ACC.

Key words: ACC oxidase;Carica papaya L.;CO_(2);Fe~(2+);Inhibitor;Kn;Value

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Citing This Article：

Song Songquan, Yip Wing-Kin. Effect of O_(2), ACC and CO_(2) concentration on the activity of partially purified ACC oxidase from papaya. Acta Physiol Sin 2001; 53 (5): (in Chinese with English abstract).