水稻幼芽细胞生物膜上的赤霉素结合蛋白的结合特性

CHARACTERIZATION OF THE MEMBRANE BOUND GIBBERELLIN BINDING PROTEINS FROM YOUNG SHOOTS OF RICE

在水稻 (Oryza sativa)幼芽中存在膜结合的赤霉素结合蛋白 ,其与 GA3 结合的平衡解离常数(Kd)为 6.5× 1 0 -8mol/ L,总浓度为 0 .3 pmol· mg-1 蛋白质。结合蛋白与 GA3 结合活力在 0℃时比 2 5℃时高 1 4 0 %。它与 GA3 结合的最适 p H为 5。 GA3 与此结合蛋白的结合量随反应时间延长而增加 ,1 h达最大值 ,以后又逐渐下降。 IAA、ABA可与 GA3 竞争赤霉素结合蛋白。

Gibberellin binding proteins were found on the membrane of young rice shoot.The dissociation constant (Kd) for GA 3 was approximately 6.5×10 -8 mol/L,and the total concentration of the sites was 0.3 pmol·mg -1 protein.The binding activity of gibberellin binding proteins was significantly affected by temperature and pH,which was 140% higher at 0 ℃ than that at 25 ℃,and the optimal pH value was 5.Gibberellin binding activity increased with the incubation time, reaching the maximum at 1 h,and then decreased gradually.Both IAA and ABA were able to compete with GA 3 for gibberellin binding proteins.