Cell membranes are extraordinarily heterogeneous environments composed of a multitude of different molecules with many thousands of chemically distinct lipids, sterols, and proteins. It is this very complexity and diversity of membrane composition that allows for its many varied and critical biological functions. These membranes are rather thin, only 3 nm to 5 nm thick, and present both structural and dynamic features on a wide variety of length and time scales. Within that hierarchy of length and time scales, the membrane's mechanical properties control many of the key functions such as bilayer shape transformations, protein binding, budding, and molecular transport which in turn are related to such things as apoptosis, endocytosis, protien signaling and drug delivery. In this chapter, we will review how the elastic properties of membranes control the membranes' dynamics by presenting experimental results obtained by means of neutron spin echo spectroscopy. Towards the end of the chapter, we will consider another interesting property, membrane viscosity, and discuss some future aspects and challenges.
Characterization of Biological Membranes
Walter de Gruyter, Inc., Boston, MA
lipid, membrane, dynamics, neutron scattering, neutron spin echo, bending modulus, area compressibility modulus, membrane viscosity