光谱法及分子模拟分析大豆皂苷II与牛血清白蛋白的相互作用

采用内源荧光光谱、圆二色光谱以及分子模拟表征了大豆皂苷Ⅱ与牛血清白蛋白（BSA）之间的相互作用。内源荧光光谱显示，大豆皂苷Ⅱ使BSA最大发射波长略微蓝移且出现荧光猝灭，色氨酸残基的微环境疏水性增加，蛋白质分子构象发生改变；大豆皂苷Ⅱ也使BSA的圆二色光谱负椭圆率下降，肽链伸展，改变了BSA的二级结构。计算机模拟分子对接显示了两者稳定的结合，大豆皂苷Ⅱ的阿拉伯糖基及鼠李糖基与BSA形成氢键作用，参与其中的重要氨基酸有Asp108、Asp111、Arg144和Arg458，皂苷的三萜烯部分则伸进由15个氨基酸残基构成的疏水腔中形成疏水相互作用。
Intrinsic fluorescence spectrometry，circular dichroism spectrometry and molecular modeling methods were used to investigate the interaction between soyasaponin II and bovine serum albumin（BSA）. Results showed that the adding of soyasaponin II caused the fluorescence quenching and a decrease of the maximum emission wavelength，leading to the increase of hydrophobicity around tryptophan and the change of tertiary structure of BSA. The binding of soyasaponin II also reduced the negative ellipticity of circular dichroism spectra，unfolded the peptide chain and changed the secondary structure of BSA. Molecular docking revealed a good binding of soyasaponin II to BSA，with arabinopyranosyl and rhamnopyranosyl parts of the sugar chain forming hydrogen bonds with Asp108，Asp111，Arg144 and Arg458，and the aglycone moiety interacting with 15 amino acids by hydrophobic interaction