Models for lipid organization in cholesterol-phospholipid bilayers including cholesterol dimer formation

Area of Science:

• Biophysics
• Materials Science

Background:

• Phospholipid bilayers are fundamental to cell membranes.
• Cholesterol significantly influences membrane physical properties.

Purpose of the Study:

• To propose new structural models for cholesterol in phospholipid bilayers.
• To correlate these models with observed changes in physical properties.

Main Methods:

• Development of three distinct structural models for cholesterol aggregation.
• Analysis of molar concentrations and their impact on bilayer structure.

Main Results:

• Model 1: Cholesterol monomers accommodate up to 22% cholesterol.
• Model 2: Cholesterol dimers accommodate up to 31% cholesterol.
• Model 3: Cholesterol dimers with shared chains accommodate up to 47% cholesterol.
• Higher concentrations lead to cholesterol aggregation and phase separation.

Conclusions:

• Structural models provide a framework for understanding cholesterol's role in membrane properties.
• Abrupt property changes are linked to specific cholesterol aggregation states.