研究探讨了薯蓣皂苷（DS）对人血清白蛋白（HSA）的作用机制。运用dock 6.0分子对接法、荧光发射光谱法和紫外分光光度法，对DS同人体HSA之间的关系展开分析。DS与HSA之间有8种结合方式，再结合Grid打分值和Internal energy水平，选择第8种优势构象，Grid分数为-75.9787 kcal/mol，作用力为疏水作用，结合的氨基酸残基主要是色氨酸Trp214。荧光光谱显示DS浓度增大，HSA-DS荧光强度降低且波长蓝移，表示在DS作用下，HSA所含色氨酸（Trp）的荧光强度出现猝灭现象。波长差Δλ=15 nm和Δλ=60 nm条件下测定的同步荧光现象说明两者结合后，HSA所含Trp残基的附近环境随即出现了变化。根据Stern-Volmer方程计算得出双分子碰撞常数Kq均大于2.0×1010 L/mol·s和静态猝灭结合常数Ka均大于5×104 L/mol，证实猝灭机制属于疏水作用影响的静态猝灭，结合位点为1，与分子对接结果一致。紫外吸收图谱显示DS浓度增加，吸光度升高，进一步阐明彼此发生了作用。分子对接及光谱表明两者主要在色氨酸Trp214位置处通过疏水作用结合，HSA构象和微环境产生变化。从研究中获得的数据能够阐明薯蓣皂苷对HSA的作用机制，为进一步理解薯蓣皂苷在人体的贮藏运输过程中对蛋白质功能的影响提供新依据。

In this research, the mechanism of action of dioscin (DS) on human serum albumin (HSA) was investigated. The relationship between DS and HSA was investigated using dock 6.0 molecular docking methods, fluorescence emission spectroscopy and ultraviolet spectrophotometry. There were 8 binding modes between DS and HSA. On the combined basis of the Grid score and internal energy level, The 8th dominant conformation (with a Grid score as -75.9787 kcal/mol) was selected (in which the interactive force was hydrophobic interaction with the main bound amino acid residue being tryptophan Trp214). The fluorescence spectra revealed that with the increase of DS concentration, the HSA-DS fluorescence intensity decreased accompanied by a blue shift, indicating the quenching of the fluorescence of tryptophan (Trp) in HAS under the action of DS. The synchronous fluorescence detected under the conditions of wavelength difference Δλ=15 nm and Δλ=60 nm indicates the immediate changes in the surrounding environment of the Trp residue contained in HAS upon the binding of DS and HAS. The calculations based on the Stern-Volmer equation revealed that the bimolecular collision constant Kq was higher than 2.0×1010 L/mol·s and the static quenching binding constant Ka was higher than 5×104 L/mol. These findings confirmed that the quenching mechanism was static quenching involving hydrophobic interactions with one binding site, and were in agreement with the molecular docking results. The UV absorption spectra showed that an increase of DS concentration corresponded to an increased absorbance, indicating further the interactions between DS and HSA. Molecular docking and spectroscopy analyses showed that DS and HSA were bound mainly at the Trp214 position of tryptophan via hydrophobic interactions, and HSA underwent conformational and microenvironmental changes. The data obtained from this research clarify the mechanisms underlying the action of dioscin on HSA, and provide a new basis for further understanding of the effect of dioscin on protein function during its storage and transportation within the human body.

江苏省自然科学基金资助项目（BK20180273）；江苏省高等学校自然科学研究面上项目资助（17KJB350015）；江苏省高等职业教育产教融合平台立项项目（苏教[2019]31号）；江苏医药职业学院科技创新团队资助项目（20188103）