QUANTIFYING ACYL CHAIN INTERDIGITATION IN SIMULATED BILAYERS VIA DIRECT TRANSBILAYER INTERACTIONS.

Area of Science:

• Membrane biophysics
• Computational lipidomics
• Molecular dynamics simulations

Background:

• Lipid bilayer properties are influenced by interleaflet hydrocarbon chain interactions.
• Interdigitation, where acyl chains cross the bilayer midplane, is understood in gel phases but less so in fluid phases.
• Existing computational methods for studying dynamic interdigitation are limited in resolution.

Purpose of the Study:

• To introduce novel computational protocols for quantifying dynamic lipid chain interdigitation in fluid bilayers.
• To provide high temporal and spatial resolution analysis of interleaflet lipid interactions.
• To offer experimentally testable hypotheses for membrane biophysics.

Main Methods:

• Developed three novel protocols for quantifying acyl chain interdigitation.
• Utilized atomistic molecular dynamics simulations.
• Analyzed instantaneous interactions at the individual carbon atom level.

Main Results:

• The new methods provide detailed temporal and spatial resolution of dynamic interdigitation.
• Compared methods on bilayers with varying sn-1 and sn-2 chain length mismatches.
• Metrics offer complementary insights into lipid-lipid contacts at the bilayer midplane.

Conclusions:

• The developed protocols offer a deeper understanding of fundamental molecular mechanisms in bilayer structure and dynamics.
• These frameworks represent a valuable expansion of the membrane biophysics toolkit.
• The methods are based on freely available software and are easy to implement.