Issue Archive

Diurnal changes of phosphoenolpyruvate carboxykinase activity, oxalacetate content and adenosine pool in pineapple leaves

Lin Guifang, Peng Changlian, Lin Zhizhu, Li Shuangshun

South China Institute of Botany, The Chinese Academy of Sciences. Guangzhou, Guangdong

Abstract

The day/night cycles of decarboxylation and carboxylation of phosphoenolpyruvate carboxykinase (PEPCK)and the levels of its substrate oxalacetate, ATP and ADP from greenhouse-grown pineapple leaves were studied. The diurnal change in both forward and reverse activities of PEPCK showed a two-peak pattern with a maximum at noon(12h)and another smaller one at midnight (21h). The average decarboxylation/carboxylation ratio in the morning was higher than those in the afternoon and night time. The contents of malate and oxalacetate increased at night and reached their maxima in the morning (6h~9h)and then declined. OAA/malate ratio was higher in day time than atnight. The day/night cycles of the activities of PEP carboxylase and malate dehydrogenase were coincident with that of PEPCK activity. ATP and ADP contents increased progressively from 9h to 15h and then decreased. It was almost undetectable through 24h to 6h. The ratio of ATP/ADP showed pronounced diurnal fluctuation. The results suggested that the substrate level was the important factor regulating PEPCK activity and its catalytic direction, and the activity of PEPCK was related with the activties of PEP carboxylase and ......

Key words: PEP carboxykinase;Oxalacetute;ATP;ADP;Pineapple

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Lin Guifang, Peng Changlian, Lin Zhizhu, Li Shuangshun. Diurnal changes of phosphoenolpyruvate carboxykinase activity, oxalacetate content and adenosine pool in pineapple leaves. Acta Physiol Sin 1994; 46 (4): (in Chinese with English abstract).