Study on the noncovalent interactions of saikosaponins and cytochrome c by electrospray ionization mass spectrometry
Study on the noncovalent interactions of saikosaponins and cytochrome c by electrospray ionization mass spectrometry
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电喷雾电离质谱研究柴胡皂苷与细胞色素c的非共价相互作用
DOI：
10.1002/rcm.6151
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发表时间：
2012-04-15
影响因子：
2
通讯作者：
Wang, Xian
中科院分区：
文献类型：
--
作者：
Liu, Yingzhi;Su, Bo;Wang, Xian
原理：研究蛋白质和药物分子之间的相互作用，包括天然提取物，已经成为生物和生物医学研究中越来越感兴趣的问题。用电喷雾电离质谱仪(ESI-MS)研究了柴胡皂苷与细胞色素c(Cytc)的相互作用。柴胡皂苷类化合物是由糖类和三萜皂苷元组成的糖苷类化合物。方法：7种糖类和三萜类模型分子，分别为麦芽糖(MAL II)、麦芽三糖(MAL III)、棉籽糖(Raf)、水苏糖(StA)、甘草次酸(Gly)、乌索酸(URS)和油酸(OLE)。结果：在电喷雾质谱中观察到柴胡皂苷与柴胡皂苷a、c和这些糖类形成1：1和1：2的化学计量比。结果表明，在ESI-MS中没有检测到三萜类和Cytc的络合离子，而柴胡皂苷和糖类的Cytc络合物的Kd值相近。这说明柴胡皂苷中的糖基是与细胞色素c有效相互作用的基团。我们认为柴胡皂苷和糖与细胞色素c是通过氢键相互作用的。这六种配体与细胞色素c的亲和力大小顺序为：SSA>；SSC>；RAF，MAL III>；STA>；=MAL II。结论：本研究中提出的电喷雾质谱(ESI-MS)方法使我们能够研究柴胡皂苷与细胞色素C的相互作用，并允许直接测定结合常数。这些结果可以指导对配体与Cyt c.的结构结合关系的研究。版权所有(C)2012 JohnWiley&Sons，Ltd.。
RATIONALE: The study of interactions between protein and pharmaceutical molecules including natural extracts has become of increasing interest in biological and biomedical research. An investigation of the interaction between saikosaponins and cytochrome c(Cyt c) by electrospray ionization mass spectrometry (ESI- MS) is described in this study. Saikosaponins are found in Bupleurum falcatum (a flowering plant), and they are glycosides that consist of saccharides and the sapogenins of triterpenoids.METHODS: Seven model molecules of saccharides and triterpenes, namely maltose (Mal II), maltotriose (Mal III), raffinose (Raf), and stachyose (Sta), glycyrrhetinic acid (Gly), ursolic acid (Urs) and oleanic acid (Ole), were chosen to perform a series of ESI- MS control experiments for the exploration of the interaction groups in saikosaponins with Cyt c. The dissociation constants of detected noncovalent complexes were determined by using a direct ESI-MS assay.RESULTS: We have observed in the ESI mass spectra the formation of Cyt c complexes with saikosaponins a and c, and these saccharides, with 1: 1 and 1: 2 stoichiometry. Our results showed that no complex ions of triterpenes and Cyt c were detected in the ESI- MS and similar Kd values were obtained for the Cyt c complexes of saikosaponins and saccharides. This demonstrates that the glycosyl moiety in the saikosaponins is the effective interaction group with Cyt c. We propose that saikosaponins and saccharides interact with Cyt c by hydrogen bonds. The binding affinity of these six ligands with Cyt c is shown to be in the order Ssa> Ssc> Raf, Mal III> Sta >= Mal II.CONCLUSIONS: The ESI- MS methodology presented in this study enables us to investigate the interactions of saikosaponins with Cyt c, and allows the direct determination of binding constants. These results could guide research for providing insights into the structure- binding relationship of ligands with Cyt c. Copyright (C) 2012 JohnWiley & Sons, Ltd.