Tang Jianghong, Lian Ning, Bi Chenglu, Li Weihua
School of Chemistry and Chemical Engineering, Jiangsu Teachers University of Technology, Key Laboratory of Precious Metal Chemistry and Technology of Jiangsu Province, Changzhou 213001, China.
J Pharm Pharmacol. 2007 May;59(5):637-43. doi: 10.1211/jpp.59.5.0003.
The interaction of eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone) with human serum albumin (HSA) was studied at simulative physiological pH, with a HSA concentration of 3.0 x 10(-6)mol L(-1) and eupatilin concentrations over the range of 6.0 x 10(-6) to 1.9 x 10(-5) mol L(-1). Fluorescence spectroscopy in combination with UV absorption spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to study the binding properties (including binding mechanism, the binding constants, the number of binding sites and the binding mode) of the interaction of eupatilin with HSA and the effect of this drug on HSA conformation changes. According to the Scatchard equation there was only one class of binding site that could bind to HAS; the binding constants were 1.53 x 10(5), 1.20 x 10(5), 1.05 x 10(5), 0.87 x 10(5) L mol(-1) at temperatures of 287, 298, 310 and 318 K, respectively. The FTIR spectra revealed that the protein secondary structure changed, with reductions in alpha-helices of about 3.65% at a drug to protein molar ratio of 3. The thermodynamic analysis (enthalpy and entropy change: DeltaH(0) and DeltaS(0)) and the computational modelling study indicated that hydrophobic force played an important role in eupatilin-HSA complex stabilization, and eupatilin could bind within the subdomain IIA of HSA.
在模拟生理pH值、人血清白蛋白（HSA）浓度为3.0×10⁻⁶mol L⁻¹且泽兰素浓度范围为6.0×10⁻⁶至1.9×10⁻⁵mol L⁻¹的条件下，研究了泽兰素（5,7 - 二羟基 - 3',4',6 - 三甲氧基黄酮）与人血清白蛋白（HSA）的相互作用。采用荧光光谱结合紫外吸收光谱和傅里叶变换红外（FTIR）光谱，研究泽兰素与HSA相互作用的结合特性（包括结合机制、结合常数、结合位点数量和结合模式）以及该药物对HSA构象变化的影响。根据Scatchard方程，存在一类可与HSA结合的结合位点；在温度分别为287、298、310和318K时，结合常数分别为1.53×10⁵、1.20×10⁵、1.05×10⁵、0.87×10⁵L mol⁻¹。FTIR光谱显示蛋白质二级结构发生变化，在药物与蛋白质摩尔比为3时，α - 螺旋减少约3.65%。热力学分析（焓变和熵变：ΔH⁰和ΔS⁰）以及计算模拟研究表明，疏水作用力在泽兰素 - HSA复合物稳定中起重要作用，且泽兰素可结合在HSA的IIA亚结构域内。
