Effects of CBD on POPC membrane via MD simulations and H2 NMR. (a and b) The effects of CBD on POPC membrane area per lipid and lipid diffusion. System 0 is the control; system 1 is two CBD molecules in symmetry (one in each leaflet); system 2 is three CBD molecules in asymmetry (only in a single leaflet); and system 3 is six CBD molecules in symmetry (three in each leaflet). Area per lipid (a) and mean square displacement as a function of time (b) are not affected by CBD. (c) Distribution of CBD into the membrane across a range of conditions. The distribution of phosphate groups is shown as solid lines and the distribution of CBD is shown as dotted lines. The bilayer thickness remains ∼4 nm in the presence and absence of CBD. (d) Order parameter of lipid acyl chains estimated from the MD simulations. (e) Snapshot of a CBD molecule in the POPC leaflet extracted from the MD simulations (see Video 1). The zoomed-in image shows localization of CBD molecule below the leaflet headgroup. (f) NMR spectra collected at 20°C. (g) The spectra in f have been dePaked, showing doublets that correspond to individual palmitoyl methylene and methyl groups. The frequency separation of a given doublet is directly proportional to its order parameter. (h) The effect of CBD on the NMR order parameter profile of POPC-d31’s palmitoyl chain.
