Structural changes in lipid bilayers and biological membranes caused hydrostatic pressure.

Area of Science:

• Biophysics
• Materials Science
• Structural Biology

Background:

• Lipid bilayers are fundamental to cell membranes.
• Cholesterol modulates membrane properties.
• Understanding pressure effects on lipid bilayers is crucial for biological and technological applications.

Purpose of the Study:

• To investigate the structural response of lipid bilayers and purple membranes to high pressure.
• To determine the compressibility of lipid bilayers with and without cholesterol.
• To elucidate the effects of pressure on lipid chain packing and bilayer thickness.

Main Methods:

• Neutron diffraction was employed to measure structural parameters.
• Experiments were conducted on oriented lipid multilayers, multilamellar vesicles, and purple membrane patches.
• Pressures up to 2 kbar were applied.

Main Results:

• Oriented lipid/cholesterol multilayers showed in-plane compression and increased thickness under pressure.
• Multilamellar vesicles in the liquid crystalline state exhibited increased d-spacing with pressure.
• Lipid bilayers in the gel state showed decreased d-spacing and anisotropic chain compression.
• Bilayer compressibility values were determined for different lipid phases and compositions.

Conclusions:

• Lipid bilayers undergo significant structural changes under hydrostatic pressure.
• Cholesterol influences the compressibility and structural response of lipid bilayers.
• Pressure-induced structural alterations in lipid bilayers have implications for membrane function and stability.