Speaker
Description
Lipid molecules are basic building blocks for biological membranes, which are highly dynamic and provide a platform for various biological functions. From a materials point of view, these membranes are a visco-elastic entity. Viscosity of membranes regulates the transport of lipids and proteins in the membrane which determine the time necessary to maintain the functions. Chemically distinct lipid molecules are known to form membranes with different compositions depending on the secretory pathway. For example, more unsaturated lipids prepare membranes in early secretory pathways where the membrane viscosity is relatively lower, while more sterols and saturated lipid molecules are known for membranes in a late secretory pathway where the membrane viscosity is higher. Although biology uses different lipid compositions to maintain membrane viscosity, the molecular mechanisms of regulating the membrane viscosity are not well understood. In a previous neutron spin echo result, the slow component of the lipid acyl tail correlation relates to the transport of the lipid molecules and relates to the molecular origin of the membrane viscosity. Here, we employ quasielastic neutron scattering to measure lipid acyl tail correlation dynamics for saturated lipid membranes by utilizing isotope substitution and polarization analysis to separate coherent and incoherent components at the lipid acyl tail correlation peak. The results show that the timescale of the relaxations for self-motion of hydrogen is slightly faster than the collective dynamics in 10 ps and longer time scales. We will provide the analysis results together with some neutron spin echo data.
