Examining the phase transition behavior of amphiphilic lipids in solution using statistical temperature molecular dynamics and replica-exchange Wang-Landau methods.
Examining the phase transition behavior of amphiphilic lipids in solution using statistical temperature molecular dynamics and replica-exchange Wang-Landau methods.
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DOI：
10.1063/1.4816520
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发表时间：
2013-08
期刊：
影响因子：
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通讯作者：
Lili Gai;T. Vogel;Katie A. Maerzke;C. Iacovella;D. Landau;P. Cummings;C. McCabe
中科院分区：
文献类型：
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作者：
Lili Gai;T. Vogel;Katie A. Maerzke;C. Iacovella;D. Landau;P. Cummings;C. McCabe
两种不同的技术-复制交换Wang-Landau（REWL）和统计温度分子动力学（STMD）-被应用到系统地研究自组装脂质的相变行为作为温度的函数，使用非晶格脂质模型。这两种方法都允许直接计算态密度，与原始的Wang-Landau方法相比，效率有所提高。本文研究了两亲性脂质在水溶液中的三段模型，考察了两亲性脂质在不同浓度和不同粒子间相互作用能下的溶解行为。脂质分子相对于双层形成的相行为的特征在于通过计算的热容作为温度的函数，除了各种顺序参数和一般的目视检查。通过这两种方法进行的模拟可以达到非常低的温度，整个系统表现出良好的有序结构。通过优化参数，在所研究的温度范围内观察到几种双层相，包括具有冷冻水的凝胶相双层，混合水（即，冷冻和液态水），和液态水，以及具有液态水的更易流动的双层。从这两种方法，STMD和REWL，得到的结果是一致的，彼此非常一致，从而验证了方法和结果。
Two different techniques - replica-exchange Wang-Landau (REWL) and statistical temperature molecular dynamics (STMD) - were applied to systematically study the phase transition behavior of self-assembling lipids as a function of temperature using an off-lattice lipid model. Both methods allow the direct calculation of the density of states with improved efficiency compared to the original Wang-Landau method. A 3-segment model of amphiphilic lipids solvated in water has been studied with varied particle interaction energies (ε) and lipid concentrations. The phase behavior of the lipid molecules with respect to bilayer formation has been characterized through the calculation of the heat capacity as a function of temperature, in addition to various order parameters and general visual inspection. The simulations conducted by both methods can go to very low temperatures with the whole system exhibiting well-ordered structures. With optimized parameters, several bilayer phases are observed within the temperature range studied, including gel phase bilayers with frozen water, mixed water (i.e., frozen and liquid water), and liquid water, and a more fluid bilayer with liquid water. The results obtained from both methods, STMD and REWL, are consistently in excellent agreement with each other, thereby validating both the methods and the results.