Molecular dynamics simulation of interlayer water embedded in phospholipid bilayer

•MD simulation is used to study the stability of water embedded in a lipid bilayer.•Formation of cylindrical water droplet preceded the escape of the water molecules.•Spontaneous pore structure is observed from the localized deformation of the bilayer.•Formation of the pore structure depended on the water content.•Local permeability depended on the water content and membrane rigidity.

1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayer with a thin layer of water molecules inserted in the hydrophobic region was simulated at 300 K to observe the pore structure formation during escape of the water molecules from the hydrophobic region. The transformation of the water slab into a cylindrical droplet in the hydrophobic region, which locally deformed the lipid monolayer, was prerequisite to the pore formation. If the thickness of the interlayer water was increased beyond a critical value, the local deformation was suppressed as such deformation would rupture the lipid bilayer. Hence, it was demonstrated that the pore structure formation or local permeability of the lipid membrane is closely related to the rigidity of the lipid membrane.

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