Effects of composition on the properties of phospholipid bilayers

Burley, Andrew (2013). Effects of composition on the properties of phospholipid bilayers. University of Birmingham. Ph.D.

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Abstract

The composition of biological phospholipid membranes has a significant effect on many processes which is as yet poorly understood. Dimyristoyl-phosphatidyl-serine (DMPS) and dimystristoyl-phosphatidyl-ethanolamine (DMPE) are commonly found in cell membranes. The properties of supported bilayers composed of mixtures of these two phospholipids were investigated using electrochemical techniques, infrared spectroscopy and neutron reflectometry.
Polarisation-modulated infrared reflectance spectroscopy investigations suggest that the lipid tail groups adopt one conform at 20% DMPS and a different conformation at 30% DMPS concentration in DMPE. Differential capacity measurements show that bilayers composed of 20% DMPS or less behave similarly to pure DMPE while at 40% DMPS concentrations or higher the bilayer behaves similarly to pure DMPS. Electrochemical impedance spectroscopy indicates that bilayers containing DMPS are more effective barriers to the passage of anions than DMPE bilayers: the opposite is true for cations. It is hypothesized that the negative charge residing on the DMPS head group plays a major role in these changes. Neutron reflectometry data indicate that a 10% DMPS bilayer gains water and finally detaches from the substrate when it is subjected to an increasing negative potential. These observations help explain the shape of the capacity curve with potential.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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