We investigate the molecular driving force of domain registration of PEG-PBD diblock-copolymers, which mimic lipid raft registration, through simulations. Lipid rafts are microdomains that contain enriched levels of sphingolipids, cholesterol, and proteins. Typically, these domains are found to register across the membrane, that is, an enriched domain in one side of the bilayer corresponds to an enriched domain on the other side of the leaflet. Revealing the molecular driving force of raft registration could lead to better understanding of the mechanism of critical cellular processes such as signaling and membrane functions. In this study, we investigate the structure and dynamics of the rafts and registration characteristics utilizing a coarse-grained molecular dynamics simulations of a diblock copolymer model which mimic lipid rafts. Density profiles and order parameter profiles are analyzed and found to be consistent with the hypothesis that raft registration is an entropic-driven process. Specifically, the density profiles show spontaneous raft registration while the order parameter profiles show that the hydrophobic tails of the overall polymers in the whole system become more disordered upon registration.Furthermore, with the free energy calculations performed, we were able to show that the entropy change is positive, ~0.3Kcal/mol. This supports our hypothesis, that is the domain registration is an entropic-driven process. With an understanding of the molecular interaction, we could utilize and/or modify the function of these rafts, possibly preventing unwanted or enhancing specific cellular interactions.

Computational investigation of domain registration of membrane rafts

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.