Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
J Phys Chem B. 2013 May 2;117(17):5065-72. doi: 10.1021/jp401718k. Epub 2013 Apr 22.
Simulations of DOPC at T = 303 K were performed using the united atom force field 43A1-S3 at six fixed projected areas, A(P) = 62, 64, 66, 68, 70, and 72 Å(2), as well as a tensionless simulation that produced an average A(NPT) = 65.8 Å(2). After a small undulation correction for the system size consisting of 288 lipids, results were compared to experimental data. The best, and excellent, fit to neutron scattering data occurs at an interpolated A(N) = 66.6 Å(2) and the best, but not as good, fit to the more extensive X-ray scattering data occurs at A(X) = 68.7 Å(2). The distance ΔDB-H between the Gibbs dividing surface for water and the peak in the electron density profile agrees with scattering experiments. The calculated area compressibility K(A) = 277 ± 10 mN/m is in excellent agreement with the micromechanical experiment. The volume per lipid V(L) is smaller than volume experiments which suggests a workaround that raises all the areas by about 1.5%. Although A(X) ≠ A(N) ≠ A(NPT), this force field obtains acceptable agreement with experiment for A(L) = 67.5 Å(2) (68.5 Å(2) in the workaround), which we suggest is a better DOPC result from 43A1-S3 simulations than its value from the tensionless NPT simulation. However, nonsimulation modeling obtains better simultaneous fits to both kinds of scattering data, which suggests that the force fields can still be improved.
在 T = 303 K 下，使用 43A1-S3 统一原子力场对 DOPC 进行了模拟，在六个固定的投影面积 A(P) = 62、64、66、68、70 和 72 Å(2) 下进行了模拟，以及一个无张力模拟，产生平均 A(NPT) = 65.8 Å(2)。对由 288 个脂质组成的系统尺寸进行了小的波动校正后，将结果与实验数据进行了比较。与中子散射数据的最佳和极好拟合发生在插值 A(N) = 66.6 Å(2)处，与更广泛的 X 射线散射数据的最佳但不如好的拟合发生在 A(X) = 68.7 Å(2)处。水的 Gibbs 分界面与电子密度分布峰值之间的距离 ΔDB-H 与散射实验一致。计算出的面积压缩系数 K(A) = 277 ± 10 mN/m 与微机械实验非常吻合。每个脂质的体积 V(L)小于体积实验，这表明可以通过将所有面积提高约 1.5%来解决这个问题。尽管 A(X) ≠ A(N) ≠ A(NPT)，但对于 A(L) = 67.5 Å(2)（在解决方法中为 68.5 Å(2)），该力场与实验取得了可接受的一致性，我们建议这是 43A1-S3 模拟中比无张力 NPT 模拟更好的 DOPC 结果。然而，非模拟建模可以同时更好地拟合两种散射数据，这表明力场仍可以得到改进。
