Analysis of binary phospholipid bilayers with a self-consistent field theory

Abstract

This thesis applies a self-consistent field theory of compressible, fully hydrated phospholipid binary mixtures to an idealized model of binary bilayers. The theory is extended to calculate the average order parameter and gauche isomer number on each layer, as well as distributions of the chain-segments. It then makes calculations for a series of mixtures to present systematically the effects of composition and chain length mismatch on the structural properties, and to make comparison with experiments. In the theory, the effective fields, and the inhomogeneous particle and bond distributions throughout the bilayer interior are related self-consistently. This allows numerical calculation of all these properties. -- Experimental results for binary mixtures such as distearoylphosphatidylcholine (DSPC)/dimyristoylphosphatidylcholine (DMPC) and galactosylceramide (GalCer)/1-stearoyl-2-oleoyl phosphatidylcholine (SOPC) show the influence of chain length mismatch and composition on each component, in particular a feature called the "second plateau" in the order parameter profile near the tail of the long chain. To interpret and compare with these systems and phenomena are the foci of this work.