2 research outputs found
Dynamics of Phospholipid Membranes beyond Thermal Undulations
We
investigated the molecular dynamics of unilamellar liposomes
by neutron spin echo spectroscopy. We report the first experimental
evidence of a short-range motion at the length scale of the size of
the headgroup of a lipid. The associated mean squared displacement
shows a <i>t</i><sup>0.26</sup> dependence in the pico-
to nanosecond region that indicates another process beyond the predictions
of the Zilman–Granek (ZG) model (<i>t</i><sup>0.66</sup>) and translational diffusion (<i>t</i><sup>1</sup>). A
comparison with theory shows that the observed low exponent is associated
with a non-Gaussian transient trapping of lipid molecules in a local
area and supports the continuous time random walk model. The analysis
of the mean squared displacement leads to the important conclusion
that the friction at the interface between water and liposomes plays
a minor role. Center of mass diffusion of liposomes and transient
trapping of lipids define the range in which the ZG model can be applied
to analyze membrane fluctuations
<i>Bacillus subtilis</i> Lipid Extract, A Branched-Chain Fatty Acid Model Membrane
Lipid
extracts are an excellent choice of model biomembrane; however
at present, there are no commercially available lipid extracts or
computational models that mimic microbial membranes containing the
branched-chain fatty acids found in many pathogenic and industrially
relevant bacteria. We advance the extract of <i>Bacillus subtilis</i> as a standard model for these diverse systems, providing a detailed
experimental description and equilibrated atomistic bilayer model
included as Supporting Information to this Letter and at (http://cmb.ornl.gov/members/cheng). The development and validation of this model represents an advance
that enables more realistic simulations and experiments on bacterial
membranes and reconstituted bacterial membrane proteins