Dielectric relaxations of collagen and elastin in the dehydrated state Original Research Article

The dielectric properties of collagen and elastin, two major components of connective tissues that greatly differ in their secondary structure, were investigated in the air-dried state and at high temperatures (100–220°C). Two techniques were used to study the dielectric relaxations of both proteins: thermally stimulated currents (TSC), an isochronal spectrometry running at variable temperature, analogous to a low frequency spectroscopy (10−3–10−2 Hz) and dynamic dielectric spectroscopy (DDS), performed isothermally with the frequency varying from 10−2 to 106 Hz. A main relaxation mode is evidenced by the two techniques for collagen and elastin, located at 90°C and 145°C, respectively, at 10−3 Hz. The combination of TSC and DDS experiments and the determination of the activation parameters of the relaxation times give information on the molecular mobility of the proteins, in the glassy state and in the liquid state. Major differences between the relaxation behavior of elastin and collagen have been discussed with the fragility concept of Angell and correlated with the structure of both proteins.