Solubilization of lipid bilayers by hydrophobic polyelectrolytes

Abstract

Hydrophobic polyelectrolytes, HPEs, can solubilize lipid bilayers depending on pH. This method is currently used to isolate membrane proteins in their natural environment. HPEs contain a hydrophobic component and an ionic (weak acid or base) functional group, making them sensitive to pH. At a critical pH, the hydrophobic parts of the polymers can insert themselves into the hydrophobic tail section of the bilayer membrane, while the hydrophilic parts stick out into the medium. This may lead to solubilization of the lipid layers in the form of nano discs that are wrapped by HPE. The focus of the project is to elucidate the mechanism of the lipid bilayer solubilization induced by HPE. A better understanding of the mechanism behind disc formation could lead to applications in nanomedicine. With turbidity experiments, the dynamics and kinetics of disc formation were monitored. The pH dependence of solubilization with pEAA shows sharp transitions over a small pH range. Vesicles and discs were successfully imaged with CryoTEM. The next step is to image the intermediate states of the disc formation.