The dynamical Matryoshka model: 2. Modeling of local lipid dynamics at the sub-nanosecond timescale in phospholipid membranes

Biological membranes are generally formed by lipids and proteins. Often, the membrane properties are studied through model membranes formed by phospholipids only. They are molecules composed by a hydrophilic head group and hydrophobic tails, which can present a panoply of various motions, including small localized movements of a few atoms up to the diffusion of the whole lipid or collective motions of many of them. In the past, efforts were made to measure these motions experimentally by incoherent neutron scattering and to quantify them, but with upcoming modern neutron sources and instruments, such models can now be improved. In the present work, we expose a quantitative and exhaustive study of lipid dynamics on DMPC and DMPG membranes, using the Matryoshka model recently developed by our group. The model is confronted here to experimental data collected on two different membrane samples, at three temperatures and two instruments. Despite such complexity, the model describes reliably the data and permits to extract a series of parameters. The results compare also very well to other values found in the literature. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/486370v1_fig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@374f9corg.highwire.dtl.DTLVardef@14ba37eorg.highwire.dtl.DTLVardef@dae67corg.highwire.dtl.DTLVardef@151f721_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1:C_FLOATNO Graphical abstract. C_FIG Highlights- The Matryoshka model brings a new general description of local lipid dynamics. - Phospholipid membranes on various conditions are compared in this novel framework. - Effects of main phase transition, membrane geometry or motion direction are probed. - Despite high number of parameters, overfitting is avoided by a global fit strategy.