咪唑类离子液体与酪氨酸相互作用及机理的密度泛函理论研究  

Interaction and Mechanism between Imidazolium Ionic Liquids and the Zwitterionic Amino Acid Tyr:a DFT Study

作　　者：吴智伟 丁伟璐 张雅琴 王艳磊 何宏艳[1,3] Zhiwei Wu;Weilu Ding;Yaqin Zhang;Yanlei Wang;Hongyan He(Beijing Key Laboratory of Ionic Liquids Clean Process,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;Sino-Danish College,University of Chinese Academy of Sciences,Beijing 100049,China;Zhengzhou Institute of Emerging Industrial Technology,Zhengzhou 450000,China.)

机构地区：[1]中国科学院过程工程研究所离子液体清洁过程北京市重点实验室,北京100190 [2]中国科学院大学中丹学院,北京100049 [3]郑州中科新兴产业技术研究院,郑州450000

出　　处：《物理化学学报》2021年第10期57-66,共10页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金优秀青年科学基金(21922813);国家自然科学基金重点项目(21834006);国家自然科学基金面上项目(21978027);中国科学院前沿科学重点研究计划(QYZDB-SSW-SLH022);中国科学院青年创新促进会(2017066)资助项目。

摘　　要：离子液体的物理化学性质稳定且结构可调,被认为是潜在的新一代绿色高效生物分子溶剂。本文通过密度泛函理论研究了系列咪唑基离子液体与两性离子型氨基酸(酪氨酸)的相互作用及机理。利用对称微扰理论(SAPT)、分子中的原子理论(AIM)及约化密度梯度函数(RDG),分析了氢键作用、静电力、诱导力和色散力对离子液体-氨基酸体系相互作用的贡献。计算结果表明静电作用对于阴、阳离子与酪氨酸的相互作用占主导地位。对于系列阳离子而言,具有不同的甲基取代位点和烷基侧链长度对不同的相互作用模式会产生显著影响。其中,当甲基位于咪唑环的C2位点时,诱导力与色散力占比差别较小;当甲基取代位于咪唑环的N3位点时,诱导力与色散力占比差别较大。产生这一差异的原因在于当甲基位于C2位时,氢键、咪唑环与苯环之间的π^(+)–π作用为主要作用模式,而甲基取代位为N3位时,氢键和烷基链与苯环之间的C_(Alkyl)―H…π作用则成为主导。进一步获得离子对-酪氨酸的相互作用能变化趋势与阳离子-酪氨酸的变化趋势一致,阴阳离子的共同作用使其与酪氨酸结合更稳定。该研究结果阐明了离子液体中阳离子氢键位点及侧链长度差异对于离子液体-酪氨酸体系的相互作用模式的影响机制,为高效分离氨基酸的功能性离子液体的设计和筛选提供了新思路。Ionic liquids(ILs)are thermally and chemically stable and have adjustable structures,which gives them the potential to be used as green,efficient biomolecular solvents.Given the critical role of ILs in dissolving biomolecules,the mechanism of interaction between them deserves further study.Herein,density functional theory(DFT)calculations,using the SMD implicit water solvent model,were employed to study the interaction and mechanism between a hydrophobic zwitterionic amino acid(Tyr)and a series of imidazolium ILs with different alkyl chain lengths and methylation sites.The contributions of hydrogen bonding(H-bonding),electrostatic effects,induction,and dispersion to the intermolecular interactions were determined by combining the symmetryadapted perturbation theory(SAPT),the atoms in molecules(AIM)theory,and reduced density gradient(RDG)analysis.The results indicate that the H-bonding between the IL cation and Tyr is stronger than that between the IL anion and Tyr;however,the binding between either ion and Tyr is dominated by electrostatic effects.By contrast,the difference between the induction and dispersion forces is small when methylation occurs on the C2 site of the imidazolium cation;whereas,it is significantly large when methylation takes place on the N3 site.This is rationalized by the interaction patterns that vary based on the methylation site.H-bonding and π^(+)–πstacking interactions between the imidazole and benzene rings are dominant during C2-methylation,while H-bonding and C_(Alkyl)―H…πinteractions between the alkyl chain and benzene ring are dominant during N3-methylation.Increasing the side alkyl chain length has different effects on the interaction energy to cations with different methylation sites.During N3-methylation,when the side alkyl chain length increases from 4 to 12,there are significant van der Waals interactions between the Tyr benzene and the side alkyl chain.However,these van der Waals interactions are inapparent when methylation takes place on the C2 site.Finally,the syne

关 键 词：离子液体 两性离子型氨基酸 相互作用机理 氢键作用 范德华相互作用 

分 类 号：O641[理学—物理化学]