补骨脂素和异补骨脂素键合人血清白蛋白的比较

将互为同分异构体的两种植物药活性组分补骨脂素和异补骨脂素作为研究对象,利用荧光光谱、紫外光谱、圆二色谱及傅立叶变换红外光谱详细比较研究了这两种香豆素类化合物与人血清白蛋白(HSA)的键合作用.不同光谱的结果定性、定量地显示了HSA二级结构变化的程度.依据荧光滴定实验及Van′t Hoff公式求出了反应的热力学参数(ΔH和ΔS)的值.根据修正后的Stern-Volmer和Scatchard方程和荧光光谱数据分别求得不同温度(296,303,310及318 K)下药物与蛋白相互作用的结合常数及结合位点数;且根据F觟rster偶极-偶极能量转移理论,求得药物与HSA间的键合距离;利用竞争实验确定了药物在HSA上的键合位点为site II.从分子水平上揭示了这两种化合物与HSA相互作用的机制.

Comparison between Psoralen and Isopsoralen Binding to Human Serum Albumin

Two active components(psoralen and isopsoralen)of Chinese herbs having similar sffuctures were studied.A combination of intrinsic fluorescence spectroscopy,ultraviolet(UV)spectroscopy,circular dichroism(CD),and Fourier transform-infrared(FT-IR)spectroscopy were used to characterize the binding between the two coumarins and human serum albumin(HSA).The results from different spectra indicated qualitative and quantitative changes of the secondary structure of HSA.The thermodynamic functions,enthalpies(△H)and entropies(△S),were calculated from fluorescence titration experiments using Vant'S Hoff equation.The binding constants and number of binding sites for the drug interactions of both drugs with HSA were evaluated using the relevant fluorescence data at different temperatures(296,303,310,and 318 K) and applying modified Stem-Volmer and Scatchard equations.F(o)ster theory of dipole-dipole energy transfer was used to determine the distance between the protein residue and the bound drugs.The competitive experiments suggested that psoralen and isopsoralen bound strongly to HSA and the primary binding site for both drugswas locatedat siteⅡof HSA.