(331ag) Nanoscale Studies of Protein-Lipid Model Membranes Using Pfg NMR

Studies of the dynamics of lipids in model membranes are becoming increasingly feasible and valuble with the development of new experimental technology. Pulsed field gradient (PFG) NMR with ultra-high (up to 35 T/m) gradient strength shows superiority over current techniques due to it's non-invasive nature and high spatial resolution. Displacements of lipid molecules can be measured down to the range of 100 nm. There are two systems in which this work employs PFG NMR with ultra-high gradients to study lateral organization and dynamics. The first is a model membrane system mimicking the composition of mammalian cell membranes, which are believed to form domains known as lipid rafts. Recent experimental evidence suggests that such domains in vivo may have sizes in the range of 100 nm or smaller. Results from PFG NMR contribute to our knowledge of rafts by providing detailed data on the lateral organization and dynamics of membrane lipids on relevant length scales (i.e. down to 100 nm). Another system in this work mimics the composition of inner membranes of bacteria with and without antimicrobial peptides such as MSI-594. Antimicrobial peptides are capable of killing bacteria by disrupting their inner membranes. It is believed that the detailed knowledge of lateral diffusion in the membranes is important for understanding the mechanism of the membrane disruption by the peptides. PFG NMR with ultra-high gradients can be used to observe the influence that these peptides have on lipid organization and dynamics upon attachment. First results in this direction will be presented and discussed.