A Molecular Dynamics Simulation Study of Two Dipeptide Based Molecular Micelles: Effect of Amino Acid Order.

Kevin F Morris, Eugene J Billiot, Fereshteh H Billiot, Kenny B Lipkowitz, William M Southerland, Yayin Fang
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引用次数: 12

Abstract

Molecular dynamics (MD) simulations were used to compare the structures of the chiral molecular micelles (MM) poly-(sodium undecyl-(L,L)-leucine-valine) (poly(SULV)) and poly-(sodium undecyl-(L,L)-valine-leucine) (poly (SUVL)). Both MM contained polymerized surfactant monomers tenninated by chiral dipeptide headgroups. The study was undertaken to investigate why poly(SULV) is generally a better chiral selector compared to poly(SUVL) in electrokinetic chromatography separations. When comparing poly(SULV) to poly(SUVL), poly(SULV) had the more conformational flexible dipeptide headgroup and hydrogen bond analyses revealed that the poly(SULV) headgroup conformation allowed a larger number of intramolecular hydrogen bonds to form between monomer chains. In addition, a larger number of water molecules surrounded the chiral centers of the poly(SULV) molecular micelle. Poly(SULV) was also found to have a larger solvent accessible surface area (SASA) than poly(SUVL) and fluctuations in the poly(SULV) SASA during the MD simulation allowed dynamic monomer chain motions expected to be important in chiral recognition to be identified. Finally, approximately 50% of the Na+ counterions were found in the first three solvation shells surrounding both MM, with the remainder located in the bulk. Overall the MD simulations point to both greater headgroup flexibility and solvent and analyte access to the chiral centers of the dipeptide headgroup as factors contributing to the enhanced chiral selectivity observed with poly(SULV).

两个二肽基分子胶束的分子动力学模拟研究:氨基酸顺序的影响。
采用分子动力学(MD)模拟方法比较了聚(癸基钠-(L,L)-亮氨酸-亮氨酸)(聚(SULV))和聚(癸基钠-(L,L)-亮氨酸)(聚(SUVL))的手性分子胶束(MM)的结构。两种MM均含有手性二肽头基缠绕的聚合表面活性剂单体。本研究旨在探讨为什么在电动色谱分离中,聚(SULV)通常比聚(SUVL)具有更好的手性选择。将聚(SULV)与聚(SUVL)进行比较,聚(SULV)具有更灵活的二肽头基,氢键分析表明,聚(SULV)头基构象允许在单体链之间形成更多的分子内氢键。此外,大量的水分子包围了聚(SULV)分子胶束的手性中心。Poly(SULV)也被发现具有比Poly(SUVL)更大的溶剂可达表面积(SASA),并且在MD模拟过程中Poly(SULV) SASA的波动允许动态单体链运动在手性识别中被识别出来。最后,大约50%的Na+反离子位于MM周围的前三个溶剂化壳中,其余的位于体中。总的来说,MD模拟表明,更大的头基灵活性以及溶剂和分析物进入二肽头基手性中心的途径都是poly(SULV)观察到的手性选择性增强的因素。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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