摘要
在水稻幼苗叶片中存在膜结合的 ABA 专一结合位点。专一结合位点对 ABA 具有强的亲和力,其与 ABA 反应的平衡解离常数为2.69×10^(-7)mol/L,总浓度为4 nmol mg^(-1)蛋白质。专一结合位点与 ABA 结合活力在0℃时比25℃时高115%。专一结合位点与 ABA 结合的最适 pH 为4.5。ABA 与其专一结合位点的结合量随反应时间延长而增加,1小时达最大值,以后又逐渐降低。这种降低可能是由于专一结合使点活性逐渐减弱所致。这类结合位点可能是 ABA 进入细胞的载体,也可能是 ABA 作用的受体。
A specific ABA-binding site with high affinity was found on the membrane parts of rice seedlings.The dissociation constant(K_d)for ABA was approximately 2.66×10^(-7)mol/L,the total concentration of the sites was 4 nmol mg^(-1)protein,and the ABA-binding was maximal at pH 4.5.The activity of specific ABA-binding sites was 115%,higher at 0℃ than at 25℃. ABA-binding was increased with time,reaching maximal in 1h,and then decreased gradually. The decrease of ABA-binding may be resulted from the neutralization of the sites.The studies suggested that specific AgA-binding sites with high affinity was the carrier of ABA or,more probably,the receptor of ABA.
基金
国家自然科学基金
关键词
脱落酸
水稻
膜结合蛋白
ABA
Rice
ABA-Binding
Membrane-Bound protein
Specific ABA sites
