苋菜红的解离常数及与BSA的相互作用

The amaranth dissociation and its interactions with bovine serum albumin

利用紫外光谱法和荧光光谱法研究了苋菜红的解离常数及其与牛血清白蛋白(BSA)的结合行为。应用荧光猝灭现象和Frster理论,考察了不同环境温度和酸度下苋菜红与牛血清白蛋白的结合常数和结合位点,并对其热力学常数进行了研究。苋菜红的解离常数pKa为10.43,与牛血清白蛋白间主要存在的是疏水作用和静电作用,二者间的结合距离为3.83 nm。结合过程中静态猝灭和非辐射能量转移是导致牛血清白蛋白荧光猝灭的原因。通过同步荧光光谱和荧光探针技术证明与苋菜红作用后的BSA分子二级结构发生了变化,苋菜红与其在亚结构域IIA(Site I)发生了结合。研究结果将为苋菜红在环境和生物体内的吸收、分布、代谢等行为的探索提供一定的理论基础。

In this thesis, the dissociation constant of amaranth （AT） and its combination with bovine serum albumin（BSA） were studied by UV-visible spectrometry and fluorescence spectrometry. Based on the fluorescence quenching of BSA and Forster energy transfer mechanism, the binding constant and binding site of AT with BSA were investigated at different temperatures and acid values, and the thermodynamic constants were also studied. The results showed that the dissociation constant of AT was 10. 43. The hydrophobic force and electrostatic force played the main role in combination, and the binding distance was 3. 83 nm. In the binding process, the fluorescence quenching of BSA was resulted from non-radiative energy transfer and static quenching. The secondary structure of BSA molecules was changed after BAS binding with AT through ⅡA （Site Ⅰ）, which could be confirmed by synchronous fluorescence and the fluorescent probe technique. The study results would provide a certain theoretical basis for the absorption, distribution, and metabolism of AT in the environment and in vivo.