Poster Presentation 2014 International Biophysics Congress

Control of lipid phase behaviour by molecular design: Implications for membrane protein crystallization (#631)

Livia Salvati Manni 1
  1. University of Zurich, Zurich, Switzerland

Lipidic cubic phases (LCPs) are complex biomaterials of great potential in a variety of fundamental and applied areas such as membrane biology, drug delivery, food emulsifiers and biodevices. They exhibit a unique combination of material properties- biocompatibility, biodegradability, optical transparency, adhesivity to hydrophilic and hydrophobic surfaces, deformability, and loadability with guest molecules of virtually all polarities and charge. 

Bicontinuous LCPs are three-dimensionally ordered molecular systems made up of a geometrically well-defined, curved lipid bilayer which is surrounded by two identical, yet non-connected aqueous channels. Lipid and water molecules diffuse freely within their respective molecular subsystem, and water can diffuse between the confined channels of LCPs and an excess reservoir. Variation of hydration, temperature and pressure affect phase transitions and formation of various phases with defined material properties .
A new family of lipids with well-defined geometry and tail curvature was designed and synthesized in order to control the phase behavior and thus the material properties of the ensuing mesophases. The binary phase behavior of one such lipid was characterized by Small Angle X-ray Scattering (SAXS), and its phase diagram reveals a particularly stable Pn3m cubic phase at low temperature and absence of the high temperature, highly curved HII reverse hexagonal phase. These novel properties open up various potential applications, most notably for low temperature membrane protein crystallization from LCPs. This application addresses one of the major stumbling blocks in membrane biology- the impossibility to crystallize thermally unstable membrane protein using LCPs, and its successful development will have important impact in the field.

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