咪唑型离子液体与牛血清蛋白的缔合特性

doi:10.7517/j.issn.1674-0475.2015.01.084

摘要/Abstract

摘要：

通过紫外-可见光谱、荧光光谱、同步荧光光谱、圆二色谱、衰减全反射红外光谱、负染-透射电镜、等温滴定微量热等实验方法系统地探讨了咪唑型离子液体与牛血清蛋白(BSA)的缔合特性.结果发现,离子液体[Bmim]Cl的加入使得BSA的紫外吸收强度增加,同时也会导致其荧光猝灭,并且这种猝灭是静态猝灭.同步荧光的研究结果表明,[Bmim]Cl分子可与蛋白质中接近色氨酸残基的区域发生相互作用,使蛋白质的构象和内部的疏水结构发生改变;负染色法透射电镜直观地显示了加入离子液体后形成的蛋白质-离子液体复合物结构逐渐变大;圆二色谱和衰减全反射红外光谱表明:在离子液体与BSA缔合过程中,离子液体的加入使得BSA二级结构中的α-螺旋和β-折叠的含量降低,从而引起蛋白质二级结构的变化;表面张力法和等温滴定微量热法进一步证实上述缔合作用为静电作用和疏水作用共同作用的结果,但离子液体的烷基链与BSA疏水内腔之间的疏水作用是离子液体与BSA缔合的主要驱动力.

关键词: 离子液体, 蛋白质, 缔合特性, 作用机理

Abstract:

In the present work, UV-Vis spectroscopy, fluorescence spectroscopy, synchronous fluorescence spectroscopy, circular dichroism spectroscopy(CD), attenuated total refraction-fourier transform infrared spectroscopy(ATR-FTIR), negative staining-transmission electron microscopy, light scattering and isothermal titration calorimetry (ITC) were used to study the binding characteristics between bovine serum albumin and a typical imidazolium ionic liquid(IL), 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The results showed that the addition of [Bmim]Cl would make the UV absorption intensity of BSA increased and also lead to static fluorescence quenching. Synchronous fluorescence results suggested that [Bmim]Cl molecules mainly interact with the region which is close to the tryptophan residues of BSA, so that made the conformation and internal hydrophobic structure changed. Negative staining-transmission electron microscopy directly showed that the change of protein-IL complex structure after adding the ionic liquid. From circular dichroism and ATR-FTIR results, it was found that ionic liquid also produced a much stronger impact to α-helix, β-fold of BSA, which led to changes in protein secondary structure. Finally, ITC and surface tension methods indicated that the above interaction were driven by the electrostatic interaction and hydrophobic interaction, however, the hydrophobic interaction between the alkyl chain of IL and the internal hydrophobic microstructure of BSA was the main driving force.

Key words: ionic liquid, protein, binding characteristic, interaction mechanism

丁元华, 崔健, 戴拓苏, 郭荣. 咪唑型离子液体与牛血清蛋白的缔合特性[J]. 影像科学与光化学, 2015, 33(1): 84-97.

DING Yuanhua, CUI Jian, DAI Tuosu, GUO Rong. Binding Characteristic of Imidazolium Ionic Liquid with Bovine Serum Albumin[J]. Imaging Science and Photochemistry, 2015, 33(1): 84-97.

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