Rapid lateral diffusion of lipids is a critical property for function of biological membranes.  To better understand the principles that govern lateral diffusion, we measured diffusion rates for a large set of phospholipids that differed in their polar headgroups, ester vs. ether linkage of sn-1 and sn-2 hydrocarbon chains, hydrocarbon chain length, and degree of sn-2 chain unsaturation. Experiments were conducted over the temperature range from 10 to 60oC using 1H magic-angle spinning (MAS) NMR with application of pulsed magnetic field gradients. Most investigated lipids had perdeuterated, saturated sn-1 hydrocarbon chains that permitted measurement of chain order parameter profiles by solid-state 2H NMR.  For phosphatidylcholines we observed a decrease in diffusion rates with increasing chain length. Decreasing diffusion rates correlated with higher chain order parameters indicating a tighter lateral packing of lipids. Diffusion rates of lipids with identical hydrocarbon chains changed in the sequence phosphatidylcholine > phosphatidylserine > phosphatidylethanolamine. For lipids with increasing unsaturation of the sn-2 chain from one to six double bonds, we observed a large increase in diffusion rates that correlated with lower sn-1 chain order parameters, and a decrease in the thermal activation energy of lateral diffusion. Implications of our observations for models of lipid diffusion in bilayers will be discussed.

Influence of phospholipid chemical structure on lateral diffusion rates in fluid bilayers

243rd National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.