Thermodynamic and structural aspects of internal wool lipids

Thermotropic physicochemical techniques such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and electron paramagnetic resonance (EPR) were applied to liposomes made up of internal wool lipids. These vesicles can be regarded as a model of wool membranes. Differences in fluidity obtained from EPR allow us to deduce a high rigidity of the polar external section of the vesicle in contrast to the high fluidity of the hydrophobic internal section, which accounts for the thermotropic properties of the liposome. The coincidence of the thermotropic changes obtained with the EPR, FTIR, and DSC techniques allows us to infer a reversible phase transition temperature in the range of 30-40 degrees C, indicating a transition from a mixture of hexagonal gel-liquid crystal state to a single liquid crystal state.