DIELECTRIC-RELAXATION MODELS APPLIED TO THE DYNAMICS OF MYOGLOBIN AS DETERMINED BY MOSSBAUER-SPECTROSCOPY

Protein specific modes of motions are found in myoglobin crystals abov e 180 K, In this contribution we show that this type of motions can be analyzed by a Davidson-Cole, a Cole-Cole or a Havriliak-Negami distri bution in analogy to dielectric relaxation. However, the temperature d ependence of the obtained parameters is quite unusual indicating a bro adening of the distributions with temperature instead of motional narr owing. This can be understood from the picture of conformational subst ates if one assumes that more and more substates become accessible wit h increasing temperature. The result shows that the analogy between gl ass forming organic liquids and proteins should not be exaggerated.