The effect of peptides and ions interacting with an electrically neutral membrane interface on the structure and stability of lipid membranes in the liquid-crystalline phase and in the liquid-ordered phase

Abstract

We investigated the effects of a de novo designed peptide, WLFLLKKK (peptide-1) and La3+, which can bind with the electrically neutral lipid membrane interface, on the stability of the phosphatidylcholine (PC) membrane in the Lα phase and that of the liquid-ordered (lo) phase membranes. The results of spacing of the multilamellar vesicle and shape changes of the giant unilamellar vesicle (GUV) indicate that the peptide-1 can be partitioned into the membrane interface in the Lα phase but not into that in the lo phase. La3+ induced shape changes of GUVs of the lo phase membrane, which are the same as those of GUVs in the Lα phase. This indicates that the binding of La3+ induced an increase in the lateral compression pressure of the membrane, which decreased the surface area of the membrane in the lo phase. The difference of the membrane interface between the Lα phase and the lo phase is discussed.

Molecular Dynamics Simulations of Asymmetric NaCl and KCl Solutions Separated by Phosphatidylcholine Bilayers: Potential Drops and Structural Changes Induced by Strong Na+-Lipid Interactions and Finite Size Effects

“…Ions are known to affect membrane fusion and phase transitions (43,44). Divalent ions have also been demonstrated to change the bulk modulus of DPPC bilayers (45).…”

Vesicle Deformation by Draining: Geometrical and Topological Shape Changes

“…These include membrane fluidity, bilayer thickness, hydration state of lipid headgroups, and interfacial polarity and charge . A change in pH or ion concentrations − may result in a different lipid packing or, by a changed hydration, in an altered effective geometrical shape of the lipids. The equilibrium area per molecule at the surface is thus not a simple geometrical area but an equilibrium parameter derived from thermodynamic considerations, and it can have different values depending on temperature, salt concentrations, etc .…”

Lipid-Based Mechanisms for Vesicle Fission

“…The geometrical shape of the lipids also can cause spontaneous curvature of the membrane. This spontaneous curvature can furthermore change with varying pH or ion concentrations − such that a difference in pH value or ion concentration between the inner and outer environments of the vesicle can cause a change in the vesicle shape. For example, Sano et al found that giant unilamellar vesicles (GUVs) of dipalmitoylphosphatidylcholine/cholesterol membranes undergo shape changes when La 3+ ions are added to the aqueous solution.…”