土大黄苷与牛血清白蛋白结合反应机制及金属离子的介导作用  

Binding interactions between rhaponticin and bovine serum albumin with mediation of metal ions

作　　者：徐兴涛[1,2] 郭明[1,2] 吴志武[2] 李铭慧[2] 高兴军[2] 钱慈[1,2] 

机构地区：[1]塔里木大学生命科学学院,新疆阿拉尔843300 [2]浙江农林大学理学院,浙江临安311300

出　　处：《浙江农林大学学报》2011年第3期349-358,共10页Journal of Zhejiang A&F University

基　　金：国家自然科学基金资助项目(20877072)

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(bovineserum 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。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.]

关 键 词：土大黄苷 牛血清白蛋白 荧光光谱 紫外光谱 金属离子 

分 类 号：S852.5[农业科学—基础兽医学]