(334j) In Search Of Bilayer Undulations Via Molecular Dynamics Simulations And Principal Component Analysis

To determine how charge and lipid structure impact membrane stability, we use atomistic Molecular Dynamics simulations to study the undulatory behavior of large neutral and negatively charged lipid membranes. The results of an interesting theoretical study by Pincus et. al. found that lipid electrostatic interactions that are only partially screened by a weak electrolyte restrain bilayer undulations [1]. Besides density profile, lipid head group rotational correlation function, and order parameter comparisons, we examine global structural differences between the neutral and negatively charged bilayers using Principal Component Analysis (PCA). PCA is useful for analyzing high-dimensional data sets because it can be used to extract the dominant modes of a system. By applying PCA to lipid bilayers, we determine the relative magnitude of different fluctuation modes in the neutral and negatively charged bilayers, and through this comparison, enhance our understanding of the relationship between lipid electrostatics and experimentally obtainable parameters such as the lysis tension.

[1] Pincus, F.; Joanny, J.-F.;Andelman, D. Europhys. Lett. 1990, 11, 763.