Thermotropic phase behaviour and miscibility properties of phosphatidylcholines containing branched fatty acid chains

Abstract

Phosphatidylcholines with branched fatty acid chains were investigated by differential scanning calorimetry, X-ray diffraction, and ESR-spectroscopy. Depending on both the length of the branches in 2-position of the acyl chains and the position of the methyl branches in the acyl chains, the main-transition temperatures and enthalpies pass through a minimum. The systematic change of the phase transition parameters is connected with a modified structural polymorphism. In the gel phase the miscibility properties depend on the phase structures of the components. For one system a phase diagram with a critical point has been found.