Dehydrated bilayer simulation

GROMACS version: 2021.4
GROMACS modification: No

Hello everyone,
I want to study (via molecular dynamics simulations) the effects of dehydration in phosphatidylglycerol (PG) bilayers.

I tried to simulate just membrane + water system, and encountered some strange artifacts related with the PG-lipid tails (e.g. the angle between the sn1 and sn2 chains near 180 degrees) when the water/lipid content is below 20.

Does anyone encountered this kind of artifacts?

Just further information, I’m using the CHARMM36 + TIP3P force fields and the system in the z-axis is composed by water-membrane-water.

Best regards,

Tiago H. Ferreira

I’m not sure about phospholipids, but at least ceramides (probably also other phospholipids, see The anti-parallel, extended or splayed-chain conformation of amphiphilic lipids - ScienceDirect) get splayed at low hydration. Why do you think it’s an artifact? Also Human skin barrier formation takes place via a cubic to lamellar lipid phase transition as analyzed by cryo-electron microscopy and EM-simulation - ScienceDirect might be of interest.

Well, thank you. I didn’t know lipids could behave like this. I thought it might be some kind of artifact because in all the articles I read (MD simulation) no one reported this. Thanks again. I will investigate this matter in more detail, once you have enlightened me to a logical explanation.