Novel structural features of the ripple phase of phospholipids

TL;DR

This study uses electron density mapping to reveal a previously unobserved average tilt of lipid hydrocarbon chains in the ripple phase, explaining the formation of asymmetric ripples in phospholipid multibilayers.

Contribution

First to demonstrate the existence of an average tilt of hydrocarbon chains in the ripple phase of phospholipids using electron density maps.

Findings

Confirmed the presence of chain tilt in the ripple phase.

Linked chain tilt to asymmetric ripple formation.

Provided detailed electron density maps at various temperatures.

Abstract

We have calculated the electron density maps of the ripple phase of dimyristoylphosphatidylcholine (DMPC) and palmitoyl-oleoyl phosphatidylcholine (POPC) multibilayers at different temperatures and fixed relative humidity. Our analysis establishes, for the first time, the existence of an average tilt of the hydrocarbon chains of the lipid molecules along the direction of the ripple wave vector, which we believe is responsible for the occurrence of asymmetric ripples in these systems.