An intermolecular interaction model for selective association processes of double-chain phospholipids in bilayer lipid membranes has been proposed, analysed and solved numerically. A large variety of binary mixtures of asymmetrical double-chain phospholipids with the cross-sectional areas of the polar headgroups a1 = 40 Å2 (the first component) and a2 = 60 Å2 (the second component) have been investigated. Changing the hydrophobic acyl-chain lengths of both mixture components, we found in all cases that the self-association probability (the association of like-pairs of phospholipids) of the first component in parallel alignment of the electric dipole moments of the polar headgroups is higher than the cross-association probability (the association of cross-pairs of phospholipids) and the self-association probability of the second component. This result is in good agreement with the experimental evidence that where the cross-sectional area of the polar headgroups matches the hydrocarbon chain-packing cross-sectional area (a ≅ 2∑ ≅ 40 Å2), lipids possess a high tendency to aggregate into well packed bilayer structures with the acyl-chains oriented perpendicularly to the bilayer plane. Our theoretical data confirm that the double-chain phospholipids may associate themselves into anti-parallel alignment of the polar headgroups (P′22) as well. The hydrophobic acyl-chain effect of phospholipids may modulate the distribution of lipid domains within bilayers that have a large variety of functional roles in cellular metabolism.
- Bilayer lipid membrane
- Computer simulation
- Hydrophobic acyl-chain effect
- Lipid domains
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry