液质/光谱和计算机分子对接研究甘草素与人白蛋白的相互作用
首发时间:2012-12-27
摘要:研究甘草素与人血清白蛋白(HSA)相互作用的机制。采用平衡透析-超高液相-四级杆质谱,测得甘草素与HSA浓度比在2:1,5:1时的结合率为(66.24±1.82)%和(84.26±0.99)%,表明甘草素与HSA发生高强度结合。荧光光谱研究了甘草素对HSA的荧光淬灭效应,结果在296,302和310 K时,甘草素与HSA的结合常数Ka分别为4.92×10E6,4.04×10E6,2.69×10E6 Lomol-1,结合强度随着温度的升高而降低,说明发生静态猝灭;计算热力学常数△H:-24.36 kJomol-1,△S:45.81 Jo(mol-1oK)-1,△G: -37.92 kJomoL -1,提示疏水力和氢键是甘草素与HSA的主要作用力类型。分子对接首先进行了方法有效性和位点选择性的考察。采用了以能量评分和药物结合特征为指标的构象选择标准,筛选出甘草素在位点I的特异性构象:①甘草素的A/C环位于非极性氨基酸Leu238和Ala291之间,形成疏水性作用;②甘草素C环的环氧基和羰基以对称氢键的形式分别键合到口袋内Tyr150和口袋入口Arg222;③A环和B环的两个羟基以另一组对称氢键形式,分别键合到口袋内Arg257和入口的Ser192。甘草素在位点I的疏水力评分大于氢键,无静电力相互作用。甘草素分子的四个氧原子形成两两平衡的氢键,以及周围的疏水力,恰好将甘草素分子固定在位点I的疏水性口袋内。
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Studies on the binding of liquiritigenin with human serum albumin by liquid chromatography mass spectrometry, spectroscopy and computer modeling
Abstract:In this paper, the interaction between liquiritigenin and human serum albumin (HSA) was investigated. Equilibrium dialysis and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) were used to analyze the binding rates of liquiritigenin to HSA. The binding rate at 2:1 and 5:1 is 66.24% and 84.26%, respectively. Fluorescence data showed that the quenching of HSA by liquiritigenin was result of forming the complex of liquiritigenin-HSA. The binding parameters (296, 302 and 310 K) are 4.92×10E6, 4.04×10E6 and 2.69×10E6 Lomol-1. The enthalpy change (△H) and entropy change (△S) were calculated to be -24.36 kJmol(-1) and 45.81 Jmol(-1)K(-1), indicating that the hydrogen bonds and hydrophobic interactions played a dominant role in the binding. The molecular docking investigation revealed that the site I was the main binding site of liquiritigenin. In site I, A/C ring of liquiritigenin pinned snugly between the apolar side-chains of Leu238 and Ala291. Moreover, liquiritigenin makes hydrogen-bond interactions with Tyr150 and Arg257 inside the pocket, and Arg222 and Ser192 at the entrance of pocket, which appears particularly well adapted to the site I pocket.
Keywords: Liquiritigenin HSA Molecular docking Fluorescence spectrum UPLC-MS/MS
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