自旋标记钙调蛋白与酸枣仁皂甙A相互作用研究

Study On Interaction between Labeling Calmodulin and Jujuboside A

中草药有效成份酸枣仁皂甙A是钙调蛋白CaM的一种天然非竞争性拮抗剂。利用氮氧自由基马来酰亚胺衍生物标记CaM研究了二者的相互作用。结果表明,每分子CaM至少可以结合二个分子的酸枣仁皂钙A,二者的作用影响CaM上Lys残基主要是75,94)的环境,推测酸枣仁皂钙A是通过疏水作用结合到CaM分子两端的疏水沟区。通过比较三氟拉嗪TFP与酸枣仁皂甙A的结构特点,抑制性质与结合位点,提出了CaM调节环核苷酸磷酸二酯酶PDE的模式。

Jujuboside A,an effective component of Chinese herbal drug,inhibits the activity of calmodulin on cyclic nucleotide phosphodiesterase (PDE) noncompetiti-vely.By labeling calmodulin with Proxyl-maleimide derivative,the interaction between CaM and Jujuboside A has been studied with electron spin resonance spectroscopy.The results have shown that a calmodulin molecule can bind at least two jujuboside A with highaffinity.The binding of jujuboside A affects the environments of lysine residues of CaM (most probably Lys 75 and 94) It is likely that jujuboside A binds to CaM through hydrophobic interaction.By comparing the structural features,inhibition function and binding regions of TFP with jujuboside A,the model for regulation of PDE by calmodulin was suggested.