Prabhu Janak, Frigerio Matteo, Petretto Emanuele, Campomanes Pablo, Salentinig Stefan, Vanni Stefano
Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland.
Department of Chemistry, University of Fribourg, 1700 Fribourg, Switzerland.
J Chem Theory Comput. 2024 Sep 10;20(17):7624-7634. doi: 10.1021/acs.jctc.4c00529. Epub 2024 Aug 19.
Aqueous ionic solutions are pivotal in various scientific domains due to their natural prevalence and vital roles in biological and chemical processes. Molecular dynamics has emerged as an effective methodology for studying the dynamic behavior of these systems. While all-atomistic models have made significant strides in accurately representing and simulating these ions, the challenge persists in achieving precise models for coarse-grained (CG) simulations. Our study introduces two optimized models for sodium and chloride ions within the nonpolarizable surface property fitting coarse-grained force field (SPICA-FF) framework. The two models represent solvated ions, such as the original FF model, and unsolvated or bare ions. The nonbonded Lennard-Jones interactions were reparameterized to faithfully reproduce bulk properties, including density and surface tension, in sodium chloride solutions at varying concentrations. Notably, these optimized models replicate experimental surface tensions at high ionic strengths, a property not well-captured by the ions of the original model in the SPICA-FF. The optimized unsolvated model also proved successful in reproducing experimental osmotic pressure. Additionally, the newly reparameterized ion models capture hydrophobic interactions within sodium chloride solutions and show qualitative agreement when modeling structural changes in phospholipid bilayers, aligning with experimental observations. For aqueous solutions, these optimized models promise a more precise representation of the ion behavior.
由于水性离子溶液在自然界中普遍存在且在生物和化学过程中发挥着重要作用，因此在各个科学领域都至关重要。分子动力学已成为研究这些系统动态行为的有效方法。虽然全原子模型在准确表示和模拟这些离子方面取得了重大进展，但在实现用于粗粒度（CG）模拟的精确模型方面仍然存在挑战。我们的研究在不可极化表面性质拟合粗粒度力场（SPICA-FF）框架内引入了两种针对钠离子和氯离子的优化模型。这两种模型表示溶剂化离子，如原始的FF模型，以及非溶剂化或裸离子。非键合的 Lennard-Jones 相互作用被重新参数化，以在不同浓度的氯化钠溶液中忠实地再现包括密度和表面张力在内的体相性质。值得注意的是，这些优化模型在高离子强度下复制了实验表面张力，这是原始 SPICA-FF 模型中的离子无法很好捕捉的性质。优化后的非溶剂化模型在再现实验渗透压方面也被证明是成功的。此外，新重新参数化的离子模型捕捉了氯化钠溶液中的疏水相互作用，并且在对磷脂双层结构变化进行建模时与实验观察结果显示出定性一致性。对于水溶液，这些优化模型有望更精确地表示离子行为。
