Nanoscale Bending Dynamics in Mixed-Chain Lipid Membranes

Lipids that have two tails of different lengths are found throughout biomembranes in nature, yet the effects this asymmetry on membrane properties not well understood, especially when it comes to dynamics. Here we study nanoscale bending fluctuations model mixed-chain 14:0–18:0 PC (MSPC) and 18:0–14:0 (SMPC) lipid bilayers using neutron spin echo (NSE) spectroscopy. We find despite partial interdigitation is known persist fluid phase these membranes, collective enhanced timescales tens nanoseconds, chain-asymmetric softer than an analogous chain-symmetric bilayer with same average number carbons acyl tails, di-16:0 (DPPC). Quantitative comparison NSE results suggests at nanosecond consistent experimental computational studies showed compressibility moduli membranes 20% 40% lower membranes. These add growing evidence highly dynamic impacts processes from molecular mesoscopic length scales without significantly changing thickness or area per lipid.