Thermodynamic and structural aspects of internal wool lipids

Thermotropic physicochemical techniques such as differential scanning calor imetry (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. D ifferences 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 fluid ity of the hydrophobic internal section, which accounts for the thermotropi c properties of the liposome. The coincidence of the thermotropic changes o btained with the EPR, FTIR, and DSC techniques allows us to infer a reversi ble phase transition temperature in the range of 30-40 degrees C, indicatin g a transition from a mixture of hexagonal gel-liquid crystal state to a si ngle liquid crystal state.