Model for the structure of the lipid bilayer.
A detailed model for the structure and dynamics of the interior of the lipid bilayer in the liquid crystal phase is presented. The model includes two classes of motion: (i) the internal dynamics of the chains, determined from Brownian dynamics simulations with a continuous version of the Marcelja mean-field potential, and (ii) noncollective reorientation (axial rotation and wobble) of the entire molecule, introduced by a cone model. The basic unit of the model is a single lipid chain with field parameters adjusted to fit the 2H order parameters and the frequency-dependent 13C NMR T1 relaxation times of dipalmitoyl phosphatidylcholine bilayers. The chain configurations obtained from the trajectory are used to construct a representation of the bilayer. The resulting lipid assembly is consistent with NMR, neutron diffraction, surface area, and density data. It indicates that a high degree of chain disorder and entanglement exists in biological membranes.
Pastor
R W
RW
Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892.
Venable
R M
RM
Karplus
M
M
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D003903:Deuterium; D008051:Lipid Bilayers; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D013816:Thermodynamics
D008051:Lipid Bilayers; D015060:1,2-Dipalmitoylphosphatidylcholine; D003903:Deuterium