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全氟十二酸(PFDoA)是8~12个碳链的全氟烷酸(PFAAs)中毒性最强的新型环境污染物。已有大量研究表明PFAAs在环境中广泛积累,但对PFDoA与HSA的相互作用还处于起步阶段。本研究力争在模拟生理条件下,采用荧光猝灭法、分子模拟技术和圆二色谱确定HSA与PFDoA的相互作用机理。研究结果表明,PFDoA对HSA的猝灭是动态猝灭与形成PFDoA-HSA基态复合物引起的猝灭共同作用的结果。计算得到的结合距离(r=3.65 nm)表明,PFDoA(受体)与HSA(供体)之间的相互作用发生了非辐射能量转移。取代反应结果表明,PFDoA键合在HSA的siteⅠ位点上。分子对接进一步研究了PFDoA与HSA作用的详细结合情况,表明PFDoA通过多种作用力结合在HSA的亚域IIA内,例如,PFDoA上的O 1原子主要通过极性键与HSA上的Arg 257和Ser 287残基结合。计算得到的最优对接能量为825.87 kJ·mol~(-1),表明PFDoA对HSA有较大的结合亲和力。同步荧光光谱和三维荧光光谱研究了PFDoA对HSA构象的影响,结果显示,与PFDoA结合后,色氨酸的微环境疏水性增加,HSA的构象也发生改变。PFDoA与HSA作用前后圆二色谱二级结构的定量分析结果表明,PFDoA-HSA复合物的形成使螺旋稳定性降低。该研究结-果为全氟烷酸与HSA的动力学研究提供了理论依据和可靠数据,并揭示了生物大分子与配体相互作用的化学本质。
Perfluorooctadecanoic acid (PFDoA) is the most toxic new pollutant of perfluoroalkanoic acid (PFAAs) with 8-12 carbon chains. A large number of studies have shown that PFAAs accumulate widely in the environment, but the interaction between PFDoA and HSA is still in its infancy. In this study, we tried to determine the interaction mechanism of HSA and PFDoA by fluorescence quenching, molecular simulation and circular dichroism under simulated physiological conditions. The results show that the quenching of HSA by PFDoA is the result of the interaction between dynamic quenching and the quenching induced by the formation of PFDoA-HSA ground state complex. The calculated binding distance (r = 3.65 nm) shows that non-radiative energy transfer occurs between PFDoA (acceptor) and HSA (donor) interactions. The results of the substitution reaction show that PFDoA binds to the site I site of HSA. Molecular Docking Further study of the combined effects of PFDoA with HSA shows that PFDoA binds to subdomains IIA of HSA via multiple forces. For example, O 1 atoms on PFDoA are mainly linked to Arg 257 and Ser 287 residues. The calculated optimal docking energy is 825.87 kJ · mol ~ (-1), indicating that PFDoA has a greater binding affinity to HSA. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy were used to study the effect of PFDoA on the conformation of HSA. The results showed that after the binding of PFDoA, the hydrophobicity of tryptophan increased and the conformation of HSA changed. Quantitative analysis of the secondary structure of circular dichroism before and after PFDoA and HSA showed that the formation of PFDoA-HSA complex decreased the stability of the helix. This study provides the theoretical basis and reliable data for the kinetics of perfluoroalkanoic acid and HSA and reveals the chemical nature of the interaction between biological macromolecules and ligands.