离子与N的相互作用通过分子动力学模拟研究了水合离子液体(IL)中甲酸甲铵(MAF)在不同浓度下的-甲基乙酰胺(NMA)。由于相互作用取决于电位的选择,本研究旨在利用基于力场的经典分子动力学(CMD)和第一原理分子动力学(FPMD)模拟来比较MAF的阳离子和阴离子与NMA的肽键的优先结合。NMA与阴离子形成稳定的氢键网络。第一原理分子动力学模拟预测纯IL中氢与阴离子和阳离子的相互作用。相反,经典的分子动力学模拟提供了NMA仅与阴离子的强相互作用的证据。但是,在有水作为助溶剂的情况下,NMA与阳离子相互作用。水分子促进更重要的阳离子-阴离子距离,从而降低了离子之间的静电相互作用。在水溶液中,与纯IL相比,实体的自扩散性增加。停留时间的值随着IL浓度的增加而增加。氢键自相关函数的分析表明,随着IL浓度的增加,短程力增加,同时,分子间氢键的寿命也增加。在NMA阳离子和NMA阴离子之间,NMA阴离子氢键的强度比前者强。与FPMD模拟相比,优先溶剂化是由于预定义的经典电势的性质。与纯IL相比,实体的自扩散性增加。停留时间的值随着IL浓度的增加而增加。氢键自相关函数的分析表明,随着IL浓度的增加,短程力增加,同时,分子间氢键的寿命也增加。在NMA阳离子和NMA阴离子之间,NMA阴离子氢键的强度比前者强。与FPMD模拟相比,优先溶剂化是由于预定义的经典电势的性质。与纯IL相比,实体的自扩散性增加。停留时间的值随着IL浓度的增加而增加。氢键自相关函数的分析表明,随着IL浓度的增加,短程力增加,同时,分子间氢键的寿命也增加。在NMA阳离子和NMA阴离子之间,NMA阴离子氢键的强度比前者强。与FPMD模拟相比,优先溶剂化是由于预定义的经典电势的性质。短程力增加,同时,分子间氢键的寿命增加。在NMA阳离子和NMA阴离子之间,NMA阴离子氢键的强度比前者强。与FPMD模拟相比,优先溶剂化是由于预定义的经典电势的性质。短程力增加,同时,分子间氢键的寿命增加。在NMA阳离子和NMA阴离子之间,NMA阴离子氢键的强度比前者强。与FPMD模拟相比,优先溶剂化是由于预定义的经典电势的性质。
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Differing preferential ion binding to the peptide bond in ionic environment from classical and first principles molecular dynamics simulations
The interactions of ions with N-methylacetamide (NMA) in hydrated ionic liquid (IL), methylammonium formate (MAF), with varying concentrations were studied by molecular dynamics simulations. As the interactions depend on the choice of potential, the current study aims to compare the preferential binding of cation and anion of MAF to peptide bond of NMA utilizing force field-based classical molecular dynamics (CMD) and first principles molecular dynamics (FPMD) simulations. NMA forms a stable hydrogen bonding network with anion. First principles molecular dynamics simulations predict hydrogen bonding interaction with both anion and cation in pure IL. In contrast, the classical molecular dynamics simulations provide evidence of the strong interaction of NMA with anion only. However, NMA interacts with cation in the presence of water as a co-solvent. Water molecules facilitate the more significant cation-anion distance, which decreases the electrostatic interaction between ions. In aqueous solutions, the self-diffusivity of the entities increases as compared to pure IL. The value of residence time rises with an increase in the concentration of IL. The analysis of hydrogen bond auto-correlation function reveals that with increasing IL concentration, the short-range force increases, and simultaneously, the lifetime of intermolecular hydrogen bonds increases. Between NMA-cation and NMA-anion, the strength of the NMA-anion hydrogen bond is stronger than the former. The preferential solvation is due to nature of predefined classical potential as compared to FPMD simulations.