Harmonic behavior of trehalose-coated carbon-monoxy-myoglobin at high temperature

Embedding biostructures in saccharide glasses protects them against extreme dehydration and/or exposure to very high temperature. Among the saccharide s, trehalose appears to be the most effective bioprotectant. In this paper we report on the low-frequency dynamics of carbon monoxy myoglobin in an ex tremely dry trehalose glass measured by neutron spectroscopy. Under these c onditions, the mean square displacements and the density of state function are those of a harmonic solid, up to room temperature, in contrast to D2O-h ydrated myoglobin, in which a dynamical transition to a nonharmonic regime has been observed at similar to 180 K (Doster et al., 1989. Nature. 337:754 -756). The protective effect of trehalose is correlated, therefore, with a trapping of the protein in a harmonic potential, even at relatively high te mperature.