Location and effect of procaine on lecithin/cholesterol membranes using X-ray diffraction methods

Area of Science:

• Membrane biophysics
• Lipid-cholesterol interactions
• Pharmacology

Background:

• Lecithin/cholesterol multilayers are model systems for cell membranes.
• Local anesthetics like procaine interact with biological membranes.
• Understanding drug-membrane interactions is crucial for pharmacology.

Purpose of the Study:

• To investigate the precise location and structural effects of procaine within lecithin/cholesterol multilayers.
• To elucidate how procaine influences the organization of lipid acyl chains.

Main Methods:

• X-ray diffraction (narrow-angle and wide-angle) was employed.
• Studies were conducted on multilayers with high water content.

Main Results:

• Procaine molecules were localized with the uncharged aromatic amine group approximately 10 Å from the bilayer center.
• The polar tertiary amine group was situated in the polar head-group region.
• Procaine incorporation led to a ~30% increase in acyl chain separation spread.
• A slight reduction in the average acyl chain spacing was observed.

Conclusions:

• Procaine integrates into the lipid bilayer, with distinct localization of its polar and non-polar groups.
• Procaine significantly disorders the acyl chains within the lipid membrane.
• These findings provide insights into the mechanism of local anesthetic action at the molecular level.