The Key Laboratory of Forest Plant Ecology, Northeast Forestry University, Ministry of Education, Harbin 150040, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Feb;86:124-30. doi: 10.1016/j.saa.2011.10.017. Epub 2011 Oct 14.
In this study, the binding interactions of the water-soluble camptothecin derivatives hydroxycamptothecin (10-HCPT), topotecan (TPT), and camptothecin quaternary salt (CPT8), to bovine serum albumin (BSA) were determined using fluorescence spectra and UV-vis spectra. The results revealed that the fluorescence of BSA was strongly quenched by the binding of camptothecin derivatives to BSA. The quenching mechanism of the camptothecin derivatives was found to be static according to the Stern-Volmer equation. The binding constant and binding sites were confirmed by fluorescence quenching spectra. The thermodynamic parameters Gibbs free energy change (ΔG<0), enthalpy change (ΔH>0), and entropy change (ΔS>0) implied that the interaction process was spontaneous and endothermic, and the interaction forces between camptothecin compounds and BSA were found to be hydrophobic. According to Föster non-radioactive energy transfer, the binding distances between 10-HCPT, TPT, and CPT8, and BSA were determined to be 1.73nm, 1.63nm, and 1.61nm, respectively. The synchronous fluorescence spectra confirmed that the camptothecin compounds cannot cause conformational changes in BSA. A rapid and sensitive method for determining the binding interaction between water-soluble camptothecin derivatives and BSA was established based on these principles of fluorescence quenching.
在这项研究中，使用荧光光谱和紫外可见光谱法测定了水溶性喜树碱衍生物羟喜树碱（10-HCPT）、拓扑替康（TPT）和喜树碱季铵盐（CPT8）与牛血清白蛋白（BSA）的结合相互作用。结果表明，喜树碱衍生物与 BSA 结合强烈猝灭了 BSA 的荧光。根据 Stern-Volmer 方程，发现喜树碱衍生物的猝灭机制是静态的。通过荧光猝灭光谱确定了结合常数和结合位点数。热力学参数吉布斯自由能变化（ΔG<0）、焓变（ΔH>0）和熵变（ΔS>0）表明，相互作用过程是自发的和吸热的，并且喜树碱化合物与 BSA 之间的相互作用力是疏水的。根据福斯特非放射性能量转移，确定 10-HCPT、TPT 和 CPT8 与 BSA 的结合距离分别为 1.73nm、1.63nm 和 1.61nm。同步荧光光谱证实喜树碱化合物不会引起 BSA 的构象变化。基于这些荧光猝灭原理，建立了一种快速灵敏的测定水溶性喜树碱衍生物与 BSA 结合相互作用的方法。
