Polyethyleneimine (PEI), one of the most widely used nonviral gene carriers, was investigated in the presented work at coarse‐grained (CG) level. The main focus was on elaborating a realistic CG force field (FF) aimed to reproduce dynamic structural features of protonated PEI chains and, furthermore, to enable massive simulations of DNA–PEI complex formation and condensation. We parametrized CG Martini FF models for PEI in polarizable and nonpolarizable water by applying Boltzmann inversion techniques to all‐atom (AA) probability distributions for distances, angles, and dihedrals of entire monomers. The fine‐tuning of the FFs was achieved by fitting simulated CG gyration radii and end‐to‐end distances to their AA counterparts. The developed Martini FF models are shown to be well suited for realistic large‐scale simulations of size/protonation‐dependent behavior of solvated PEI chains, either individually or as part of DNA–PEI systems. © 2019 Wiley Periodicals, Inc.

中文翻译：

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质子化聚乙烯亚胺的马提尼力场

聚乙烯亚胺 (PEI) 是最广泛使用的非病毒基因载体之一，在粗粒度 (CG) 级别的工作中进行了研究。主要重点是阐述一个真实的 CG 力场 (FF)，旨在重现质子化 PEI 链的动态结构特征，此外，还能够大规模模拟 DNA-PEI 复合物的形成和凝聚。我们通过将玻尔兹曼反演技术应用于整个单体的距离、角度和二面角的全原子 (AA) 概率分布，参数化了可极化和不可极化水中 PEI 的 CG Martini FF 模型。FF 的微调是通过将模拟的 CG 回转半径和端到端距离与其 AA 对应物拟合来实现的。研究表明，开发的 Martini FF 模型非常适合对溶剂化 PEI 链的大小/质子化依赖性行为进行现实的大规模模拟，无论是单独还是作为 DNA-PEI 系统的一部分。© 2019 威利期刊公司。