Limited Perturbation of a DPPC Bilayer by Fluorescent Lipid Probes: A Molecular Dynamics Study

Kavli Affiliate: Gerald W. Feigenson

| First 5 Authors: Frederick A. Heberle, David G. Ackerman, Gerald W. Feigenson, ,

| Summary:

The presence and the properties of lipid bilayer nanometer-scale domains
might be important for understanding the membranes of living cells. We used
molecular dynamics (MD) simulations to investigate perturbations of a small
patch of fluid-phase DPPC bilayer upon incorporation of fluorescent
indocarbocyanine lipid probes commonly used to study membranes (DiI-C12:0,
DiI-C18:0, or DiI-C18:2). In simulations containing 1 probe per 64 total lipids
in each leaflet, an 8 – 12% decrease in chain order is observed for DPPC
molecules in the solvation shell closest to the probe, relative to a pure DPPC
bilayer. A ~5% increase in chain order is seen in the next three shells,
resulting in a small overall increase in average DPPC chain order. In
simulations with 1 probe per 256 total lipids in each leaflet, average DPPC
chain order is unaffected by the probe. Thus, these DiI probes cause an
oscillatory perturbation of their local environment but do not strongly
influence the average properties of even "nanoscopic" lipid phase domains.

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