Lanosterol and cholesterol have different effects on phospholipid acyl chain ordering

Area of Science:

• Biochemistry
• Molecular Biophysics
• Membrane Biophysics

Background:

• Phospholipids form the structural basis of cell membranes.
• Sterols like cholesterol modulate membrane fluidity and order.
• Lanosterol, a precursor to cholesterol, also interacts with membranes.

Purpose of the Study:

• To investigate the effects of cholesterol and lanosterol on phospholipid acyl chain dynamics.
• To compare the ordering effects of cholesterol and lanosterol using 2H-NMR.
• To elucidate the role of lanosterol's methyl group in membrane interaction.

Main Methods:

• Utilized 2H nuclear magnetic resonance (2H-NMR) spectroscopy.
• Studied dioleoylphosphatidylcholine labeled at acyl chain positions 9 and 10.
• Analyzed spectra in the presence of varying concentrations of cholesterol and lanosterol.

Main Results:

• Cholesterol increased the quadrupole splitting at position 9, indicating enhanced order.
• Cholesterol had minimal effect on quadrupole splittings at position 10.
• Lanosterol showed no significant effect on quadrupole splittings at positions 9 or 10, suggesting no membrane disorganization or ordering.

Conclusions:

• Cholesterol incorporation increases the order of phospholipid acyl chains near the membrane surface.
• Lanosterol does not induce the same ordering effect as cholesterol, likely due to its 14-methyl group.
• The 14-methyl group of lanosterol may hinder its ability to pack and order phospholipid chains effectively.