Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Cooperative Dynamics in a Model DPPC Membrane Arise from Membrane Layer Interactions

Published

Author(s)

Kiley Kennedy, Neha Shafique, Jack F. Douglas, Francis W. Starr

Abstract

The dynamics of model membranes can be highly heterogeneous, especially in more ordered dense phases. Experimentally, monolayers are often studied as a model system to infer the properties of membranes. To better understand the origins of this heterogeneity, as well as the degree to which monolayer systems mimic the dynamical properties of bilayer membranes, we use molecular simulations to contrast the dynamical behavior of a single-component dipalmitoylphosphatidylcholine (DPPC) lipid bilayer with that of a DPPC monolayer. DPPC is prevalent in both biological monolayers and bilayers, and we utilize the widely studied MARTINI model to describe the molecular interactions. As expected, our simulations confirm that the lateral structure of the monolayer and bilayer are nearly indistinguishable in both low- and high-density phases. Dynamically, the monolayer and bilayer both exhibit a drop in mobility for dense phases, but we find that there are substantial differences in the amplitude of these changes, as well as the nature of molecular displacements for these systems. Specifically, the monolayer exhibits no apparent cooperativity of the dynamics, while the bilayer shows substantial spatial and temporal heterogeneity in the dynamics. Consequently, the dynamical heterogeneity and cooperativity observed in the bilayer membrane case arises in part due interlayer interactions, and we indeed find a substantial inter-digitation of the membrane leaflets which apparently impedes molecular rearrangement. On the other hand, the monolayer, like the bilayer, does exhibit complex non-Brownian molecular displacements. For the monolayer system, the single particle motion can be well characterized by fractional Brownian motion, rather than being a consequence of strong correlations in the molecular motion previous observed in bilayer membranes.
Citation
Emergent Materials

Keywords

lipid membranes, monolayer, bilayer, DPPC lipid, diffusion, cooperative motion, dynamic heterogeneity

Citation

Kennedy, K. , Shafique, N. , Douglas, J. and Starr, F. (2018), Cooperative Dynamics in a Model DPPC Membrane Arise from Membrane Layer Interactions, Emergent Materials (Accessed June 20, 2024)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created December 18, 2018, Updated October 12, 2021