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Characteristics of ABA binding protein in microsome of maize roots and effects of environment stresses on its activity

Chen Jia, Zhu Meijun

College of Biological Sciences, Beijing Agricultural University.Beijing 100094

Abstract

Microvolume radioactivity ligand binding assay indicated that there were ABA binding sites in microsomes from maize roots.The amount of ABA bound was maximal at pH 6.5 and the activity was insensitive to temperature difference between 0℃and 25℃.After 5 min the amount bound reached 50% of the maximum value, which was reached after 30 min, and remained unchanged for 60 min. Trypsin digestion experiment showed that the binding sites were on the protein. The freezingthawing experiment showed that the activity of ABA binding protein depended not only on its own characteristic structure but also on some special membrane lipid micro-environment. Specific binding activity can be reduced by the reducing agent dithioerythritol. The results suggest that a reducible group, possibly a disulfide group, may be located at or near the binding site and are required for its action. The specific binding could be enhanced by stress treatment. Salt stress, osmotic stress, drought stress and heat shock treatment all increased specific binding activity, the extents of increase being 34.9, 17.8, 23.1 and 13.3% respectively.

Key words: Binding protein;ABA specific binding;Environment stress;ABA;Microsome

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Citing This Article：

Chen Jia, Zhu Meijun. Characteristics of ABA binding protein in microsome of maize roots and effects of environment stresses on its activity. Acta Physiol Sin 1996; 48 (1): (in Chinese with English abstract).