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化学学报
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化学学报 ›› 2011, Vol. 69 ›› Issue (21): 2589-2596.DOI: 10.6023/A1012275J 上一篇    下一篇

研究论文

土贝母皂苷II与人血清白蛋白相互作用机制的光谱研究

刘璐莎1，樊君*,1，胡春梅1，孙洋1，胡晓云2，赵英永3，魏嵩1，梁旭华1   

  1. (1 西北大学化工学院 西安 710069)
    (2西北大学物理系 西安 710069)
    (3西北大学生命科学院 西安 710069)
  • 投稿日期:2010-12-27 修回日期:2011-03-26 发布日期:2011-05-26
  • 通讯作者: 樊君 E-mail:fanjun@nwu.edu.cn
  • 基金资助:

    国家自然科学基金资助;陕西省科技计划项目资助

Studies on the Interaction between TubeimosideII and Human Serum Albumin by Spectroscopic Methods

Liu Lusha1 Fan Jun*,1 Hu Chunmei1 Sun Yang1 Hu Xiaoyun2 Zhao Yingyong3 Wei Song1 Liang Xuhua1   

  1. (1 School of Chemical Engineering, Northwest University, Xian 710069)
    (2 Department of Physics, Northwest University, Xian 710069)
    (3 College of Life Sciences, Northwest University, Xian 710069)
  • Received:2010-12-27 Revised:2011-03-26 Published:2011-05-26

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1192

被引次数

34

人血清白蛋白多种结合位点的存在使其成为许多药物可能的结合靶点. 土贝母皂苷具有广泛的生理和药理活性, 它与蛋白质相互作用机制的研究对于深入了解其药理药效具有重要的意义. 采用荧光光谱法研究了土贝母皂苷II (TBMSⅡ)与人血清白蛋白(HSA)之间的相互作用, 根据Stern-Volmer荧光淬灭方程计算得293, 298, 303, 308 K时TBMSⅡ与HSA相互作用的结合常数分别为1.002×105, 0.701×105, 0.514×105, 0.411×105 L•mol－1. 由实验计算出热力学参数焓变ΔH为－44.829 kJ•mol－1, 熵变ΔS为－57.497 J•mol－1•K－1, 表明分子间的氢键及疏水作用是TBMSⅡ-HSA复合物的主要作用力, 结合位点位于HSA的亚结构ⅡA, 这与分子模拟方法的结果相一致. 依据能量转移原理求得TBMSⅡ与HSA间的距离为4.95 nm|三维、同步荧光光谱及圆二色谱的结果表明TBMSⅡ的加入使HSA构象发生变化, α-螺旋结构有所下降.

关键词: 土贝母皂苷Ⅱ, 人血清蛋白, 荧光淬灭, 圆二色光谱, 分子模拟

The presence of binding sites of human serum albumin makes it possible to combine many drugs target. The efficacy of tubeimosideII (TBMSII), isolated from Bolbostemma paniculatum (Maxim), binding to human serum albumin (HSA) is critical for pharmacokinetic behavior of TBMSII. The interactions between TBMSII and HSA under simulative physiological conditions were investigated by the methods of fluorescence spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by TBMSII was the result of the formation of the TBMSⅡ-HSA complex. According to the modified Stern-Volmer equation, the binding constants (Ka) between TBMSⅡ and HSA at four different temperatures (293, 298, 303, 308 K) were 1.002×105, 0.701×105, 0.514×105, 0.411×105 L•mol－1 respectively. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) for the reaction were calculated to be －44.829 kJ•mol－1 and －57.497 J•mol－1•K－1 according to vant Hoff equation, indicating that the hydrogen bonds and hydrophobic interactions play a dominant role in the binding of TBMSII to HSA. Site marker competitive experiments indicated that the binding of TBMSⅡ to HSA primarily took place in sub-domain IIA, which was in good agreement with the results of molecular modeling study. The distance r between donor (HSA) and acceptor (TBMSII) was obtained to be 4.95 nm according to Försters non-radioactive energy transfer theory. The conformational investigation showed that the presence of TBMSII decreased the α-helical content of HSA (from 22.7% to 19.58%) and induced the slight unfolding of the polypeptides of protein, which confirmed some micro-environmental and conformational changes of HSA molecules.

Key words: tubeimosideII, human serum albumin, fluorescence quenching, circular dichroism, molecular modeling