Impact of Lipid Composition on Membrane Partitioning and Permeability of Gas Molecules

TL;DR

This study uses simulations to show how the lipid composition of cell membranes affects the transport of gas molecules like O2 and CO2.

Contribution

The study reveals how varying lipid types modulate gas permeability through membrane lipid phases.

Findings

Lipid composition significantly affects the free energy profiles of gas molecules in membranes.

Diffusion constants and gas diffusivity are modulated by the structural properties of lipid bilayers.

Both lipid and protein pathways contribute to gas transport, with lipid composition playing a key role.

Abstract

The permeation of different chemical substances across the membrane is of utmost importance to the life and health of a living cell. Depending on the nature of the permeant, the process is mediated by either the protein (e.g., membrane channels) or lipid phases of the membrane, or both. In the case of small and physiologically important gas molecules, namely O2 and CO2, the literature supports the involvement of both pathways in their transport. The extent of involvement of the lipid phase, however, is directly dependent on the nature of the lipid constituents of the membrane that determine its various structural and physicochemical properties. In this study, we use molecular dynamics simulation, as a method with sufficient spatial and temporal resolutions, to analyze these properties in heterogeneous lipid bilayers, composed of phospholipids with varied tails, sphingomyelin, and cholesterol, to different degrees. Together with the calculation of the free energy profiles, diffusion constants, and gas diffusivity, the results shed light on the importance of the lipid phase of membranes in gas transport rate and how they can be modulated by their lipid composition.

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