荧光光谱法研究灯盏花素与牛血清白蛋白相互作用

目的采用荧光光谱法研究灯盏花素与牛血清白蛋白(BSA)在生理条件下(pH 7.4)的相互作用机制。方法固定BSA浓度,依次加入不同浓度的灯盏花素溶液,在激发波长为280 nm下,290~500 nm的波长范围内进行荧光猝灭光谱、同步荧光光谱扫描。结果灯盏花素对BSA的荧光猝灭类型是静态猝灭;在温度288 K和310 K时,二者的结合常数KA分别为8.295×105和3.302×105L.mol 1;二者的结合位点数n分别为1.239 3和1.177 0。由热力学参数焓变(H=31.080kJ.mol 1)小于零和熵变(S=5.392 J.mol 1.K 1)大于零,确定灯盏花素与BSA之间的作用力类型为静电作用力;生成自由能变(G)为负值,表明灯盏花素与BSA的作用过程是一个自发过程。此外,应用同步荧光光谱考察了灯盏花素对BSA构象的影响。结论经过荧光光谱分析,可以确定灯盏花素与白蛋白的作用机制,为其开发成治疗心血管疾病新药提供理论依据。

Study on the Interaction between Breviscapinum and Bovine Serum Albumin by Fluorescence Spectrometry

OBJECTIVE To identify the interaction mechanism between breviscapinum and bovine serum albumin（BSA） under the physiological conditions （pH7.4） by fluorescence spectrometry. METHODS Fixing the concentration of BSA, different concentrations of breviscapinum were added. At excitation wavelength 280 nm, the interaction between breviscapinum and BSA was determined with quenching and synchronous spectrum from 290 nm to 500 nm. RESULTS The fluorescence quenching mechanism between breviscapinum and BSA was static quenching. The binding constants （KA） under 288 K and 310 K between breviscapinum and BSA were 8.295 × 10^5 and 3.302× 10^5 L.mol-1, respectively. The number of binding sites under 288 K and 310 K between hreviscapinum and BSA were 1.239 3 and 1.177 0, respectively. According to the thermodynamic parameters, enthalpy change （A/-/） and entropy change （AS）, which were calculated to be -31.080 kJ.mo1-1 and 5.392 J.mol-l.K-1, respectively, the interaction between breviscapinum and BSA was driven mainly by electrostatic interaction. The process of binding was spontaneous because that Gibbs free energy change was negative. Further more, synchronous spectrum was used to investigate the conformational changes of BSA. CONCLUSION In this paper, the interaction mechanism between breviscapinum and BSA was analyzed by fluorescence spectrometry. The results can be applied for the antioxidant new drugs development of breviscapinum