荧光光谱结合表面增强拉曼光谱法研究紫檀芪与人血清白蛋白相互作用

在模拟人体生理条件下,应用荧光光谱和表面增强拉曼光谱法研究了紫檀芪(PTE)与人血清白蛋白(HSA)之间相互作用机制.结果表明,HSA的荧光能被PTE静态猝灭,并伴随有非辐射能量转移作用,两者形成了1:1复合物,结合距离r=1.495 nm,结合常数KA=1.12×104(298 K)、4.07×104(304 K)和2.45×105 L/mol(310 K).表面增强拉曼光谱研究揭示,PTE分子通过甲氧基与HSA进行结合;热力学数据表明,二者间的作用主要为疏水作用;标记竞争实验指出PTE优先结合HSA的位点Ⅲ.三维荧光光谱、同步荧光光谱和表面增强拉曼光谱结果显示,与PTE作用后,HSA构象发生变化,导致色氨酸残基周围环境疏水性降低,但对PTE分子构象影响不大.

Study of Intermolecular Interactions Between Pterostilbene and Human Serum Albumin by Fluorescence Spectrometry-Surface Enhanced Raman Spectroscopy

The binding mechanism between pterostilbene ( PTE) and human serum albumin ( HSA) was investigated by fluorescence spectrometry and surface enhanced Raman spectroscopy (SERS) under simulated physiological conditions. The experiment result showed that the effect between PTE and HSA was a static fluorescence quenching with F?rsterˊ s non-radioactive energy transformation, and PTE could bind HSA strongly with a 1: 1 molar ratio. The binding distances between PTE and HSA was 1. 495 nm, and the binding constants (KA) between PTE and HSA were 1. 12 × 104 (298 K), 4. 07 × 104 (304 K) and 2. 45 × 105 L/ mol (310 K). SERS revealed that PTE combined with HAS by methoxy group. Thermodynamic data indicated that the interaction between PTE and HSA was mainly hydrophobic interaction. Marker competition experiments pointed out that the primary binding site for PTE was located at site Ⅲ in HSA. Three-dimensional, synchronous fluorescence spectrum and SERS showed that the conformation of HSA changed apparently with the addition of PTE, resulting in the tryptophan residue of HSA exposing to a less hydrophobic micro-environment. However, the conformation of PTE did not change apparently with the addition of HSA.