Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
J Phys Chem B. 2012 Feb 9;116(5):1551-69. doi: 10.1021/jp207837v. Epub 2012 Jan 25.
We study the phase behavior of saturated lipids as a function of temperature and tail length for two coarse-grained models: the soft-repulsive model typically employed with dissipative particle dynamics (DPD) and the MARTINI model. We characterize the simulated transitions through changes in structural properties, and we introduce a computational method to monitor changes in enthalpy, as is done experimentally with differential scanning calorimetry. The lipid system experimentally presents four different bilayer phases - subgel, gel, ripple, and fluid - and the DPD model describes all of these phases structurally while MARTINI describes a single order-disorder transition between the gel and the fluid phases. Given both models' varying degrees of success in displaying accurate structural and thermodynamic signatures, there is an overall satisfying extent of agreement for the coarse-grained models. We also study the lipid dynamics displayed by these models for the various phases, discussing this dynamics with relation to fidelity to experiment and computational efficiency.
我们研究了两种粗粒模型（即软排斥模型和 MARTINI 模型）中饱和脂质的温度和尾部长度依赖性的相行为。我们通过结构性质的变化来描述模拟转变，并引入了一种计算方法来监测焓的变化，这与差示扫描量热法（differential scanning calorimetry）在实验中所做的一样。实验中的脂质系统呈现出四种不同的双层相——亚凝胶相、凝胶相、纹波相和流动相，而 DPD 模型在结构上描述了所有这些相，而 MARTINI 模型则描述了凝胶相和流动相之间的单一有序无序转变。鉴于这两个模型在显示准确的结构和热力学特征方面的不同程度的成功，粗粒模型在总体上具有令人满意的一致性。我们还研究了这些模型在各种相下显示的脂质动力学，讨论了这种动力学与实验和计算效率的相关性。
