Binding interactions between rhaponticin and bovine serum albumin with mediation of metal ions
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摘要: 应用荧光光谱法结合紫外-可见分光光度法研究了中药分子土大黄苷（rhaponticin，RT）与牛血清白蛋白（bovine serum albumin，BSA）的结合反应机制，并考察了金属离子的介导作用。依据不同理论模型测定了反应体系的结合常数K、结合位点数n，并进行了分析比较，探讨了荧光猝灭机制。根据Fōrster非辐射能量转移机制确定了授体-受体间结合距离和能量转移效率。采用同步荧光技术考察了RT对BSA分子构象的影响。结果表明：不同理论模型计算的结合参数基本相符并显示出RT与BSA结合反应形成了稳定的静态复合物，RT对BSA分子的结构域微区构象产生了影响，导致BSA相应结构微区疏水环境改变。金属离子钴（Ⅱ），镍（Ⅱ）竞争RT与BSA的结合反应，使BSA-RT的结合距离发生改变。同时，提出了一个新变量-伸展度ED的计算公式，以此定量表征药物分子对蛋白质分子微区构象的影响。图8表3参31Abstract: The interaction between rhaponticin （RT） and bovine serum albumin（BSA） was studied using fluorescence spectroscopy and absorbance spectra. Based on different theoretical models of fluorescence quenching，the binding constant （K） and binding sites （n） of the interactions were determined with the effects of metal ions on the interactions considered. The binding distance （r） and energy-transfer efficiency （E） between RT/RT-Co（Ⅱ）/RT-Ni（Ⅱ） and BSA were also obtained using the Fōrster theory of non-radiation energy transfer. Results showed that RT bound BSA by forming a stable complex and the micro-conformation of BSA changed greatly due to a hydrophobic change in the chemical environment of the fluorescence chromophores within the relevant subdomains of BSA. Therefore，metal ions Co（Ⅱ） and Ni（Ⅱ） could compete with RT-BSA interactions，thereby shortening the binding distance between RT and BSA；however，to precisely quantify the hydrophobic effect and micro-conformational changes of drugs on proteins，we suggest a new formula defining the entention degree ED.［Ch，8 fig. 3 tab. 31 ref.］
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https://zlxb.zafu.edu.cn/article/doi/10.11833/j.issn.2095-0756.2011.03.002
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