Fe^(3+)存在下磺胺甲恶唑与牛血清白蛋白相互作用的光谱学研究

Spectroscopic Study of the Interaction between Sulfamethoxazole and Bovine Serum Albumin in the Presence of Fe^(3+)

在模拟生理条件下,应用荧光光谱、紫外吸收光谱以及傅立叶变换红外光谱研究Fe3+存在下磺胺甲恶唑(Sulfamethoxazole,SMZ)与牛血清白蛋白(Bovine Serum Albumin,BSA)的相互作用.结果表明,Fe3+存在时SMZ与BSA结合常数增大,作用力类型由疏水作用力转变为氢键和范德华力.无论Fe3+存在与否,SMZ与BSA之间作用机制均为静态荧光猝灭.同步荧光及三维荧光光谱表明,SMZ改变了BSA构象,Fe3+的存在没有加强SMZ对BSA有序结构的改变.从紫外吸收光谱可知,Fe3+先与SMZ形成配合物后再与BSA形成三元复合物.根据非辐射能量转移理论,求出结合位置与212位色氨酸残基距离.FT-IR光谱显示,Fe3+存在时SMZ对BSA二级结构的变化产生不同的影响.

Under the simulative human physiological condition,the interaction of sulfamethoxazole（SMZ） and bovine serum albumin（BSA） with or without Fe3＋ was studied by fluorescence spectra,ultra-violet ab-sorption spectra and FT-IR spectra.The results show that both the quenching mechanism of the intrinsic fluorescence of BSA by sulfamethoxazole with or without Fe3＋ is a static fluorescence quenching proce-dure.It was found that in the presence of Fe3＋,the binding constant of SMZ and BSA increased and the main binding force between SMZ and BSA was changed from hydrophobic force to hydrogen bonds and van der Waals force.From the synchronous fluorescence and three-dimensional fluorescence spectra,it was found that SMZ change the conformation of BSA.BSA may form a new disordered structure,but the capa-bility of SMZ changing the structure of the BSA was not enhanced in the presence of Fe3＋.Based on fluo-rescence resonance energy transfer（FRET）,the distances（r） between donor（BSA） and acceptor（SMZ and Fe3＋-SMZ） were obtained.According to FT-IR,the secondary structure of BSA changed when Fe3＋ and SMZ were added.