posted on 2016-02-19, 10:23authored byDavid
G. Ackerman, Frederick A. Heberle, Gerald W. Feigenson
The
properties of lipid bilayer nanometer-scale domains could be
crucial for understanding cell membranes. Fluorescent probes are often
used to study bilayers, yet their effects on host lipids are not well
understood. We used molecular dynamics simulations to investigate
perturbations in a fluid DPPC bilayer upon incorporation of three
indocarbocyanine probes: DiI-C18:0, DiI-C18:2, or DiI-C12:0. We find
a 10–12% decrease in chain order for DPPC in the solvation
shell nearest the probe but smaller effects in subsequent shells,
indicating that the probes significantly alter only their local environment.
We also observe order perturbations of lipids directly across from
the probe in the opposite leaflet. Additionally, the DPPC headgroup
phosphorus-to-nitrogen vector of lipids nearest the probe exhibits
preferential orientation pointing away from the DiI. We show that,
while DiI probes perturb their local environment, they do not strongly
influence the average properties of “nanoscopic” domains
containing a few hundred lipids.