多光谱法和分子对接研究α-熊果苷与人血清白蛋白的相互作用

α-熊果苷是一种能够止咳平喘的植物提取物，有关它与蛋白质的相互作用及作用机理报道较少。应用光谱学与分子对接技术研究了在不同条件下α-熊果苷与人血清白蛋白（HSA）的相互作用。研究结果显示：随着α-熊果苷浓度的增大，HSA荧光强度得到了显著增强并且荧光光谱发生了蓝移。利用荧光增敏的各种有关方程求得了α-熊果苷在不同温度下与HSA作用的结合常数, 通过范特霍夫方程计算HSA与α-熊果苷相互作用过程中的ΔH=-23.29 kJ·mol-1和ΔS=40.96 J·mol-1·K-1，说明α-熊果苷与HSA之间的主要作用力是氢键和疏水作用力。通过紫外吸收光谱、同步荧光光谱、三维荧光光谱等光谱学方法研究发现α-熊果苷使HSA的构象发生改变。通过HSA与α-熊果苷作用前后圆二色二级结构的定量分析可得知，HSA与α-熊果苷复合物的形成使蛋白质螺旋稳定性降低。最后应用分子对接实验，验证了α-熊果苷与HSA间的相互作用位点在HSA的siteⅡ（亚域ⅢA），α-熊果苷能通过氢键和疏水作用力等多种作用力很好的结合在亚域ⅢA的疏水腔中。从实验中获得的数据能够阐明α-熊果苷对HSA的作用机制，同时能够有助于理解α-熊果苷在人体的储藏运输过程中对蛋白质功能的影响。

Characterization of the Interactions between Alpha Arbutin and Human Serum Albumin with Spectroscopic Method and Molecular Docking

Alpha arbutin is a botanical extract which can relieve cough and asthma, and its effects on protein and the mechanism of action are poorly reported. This paper studied the interaction between alpha arbutin and human serum albumin (HSA) under different temperature conditions with fluorescence spectroscopy. With the increasing of alpha arbutin concentration, the fluorescence intensity of HSA was significantly enhanced with the occurrence of blue shift of fluorescence spectrum. By using fluorescence enhancement effect equations, we can obtain the binding constants of alpha arbutin and HSA. Thermodynamic parameters were obtained using the van’t Hof equation, resulting in the main type of molecular force between alpha arbutin and HSA. The thermodynamic parameters(ΔH=-23.29 kJ·mol-1 and ΔS=40.96 J·mol-1·K-1) indicated that hydrogen bond and hydrophobic were the intermolecular force. UV-Vis, Synchronous fluorescence spectrometry and Three-dimensional fluorescence spectra were utilized to explore the effects of arbutin and HSA interactions on the secondary structure of protein. The circular two color spectrometry can conclude the protein secondary structure, which indicated the loss of helical stability after the interaction of arbutin and HSA. The binding details between arbutin and HSA were confirmed by molecular docking, which revealed alpha arbutin was bound at siteⅡ (subdomain IIIA) via multiple interactions, such as hydrogen bond, hydrophobic. The full basic data in the work is to clarify the binding mechanism of alpha arbutin with HSA and is useful for understanding its effect on protein function during the blood transportation process.