Water hydrating biomolecules shows a more complex dynamical behavior when compared to the bulk. Its translational slow dynamics can be described by two mechanisms characterized by two well distinct time scales. One mechanism is the α -relaxation typical of supercooled bulk water and other glass forming liquids. Upon cooling, this relaxation shows a fragile-to-strong crossover due to the activation of hopping phenomena which permits to the water molecules in the hydration layer to escape from nearest neighbors cage. The second mechanism is a much slower relaxation that is present only in hydration water and it is coupled with the biomolecule dynamics. This long-relaxation shows upon cooling a strong-to-strong crossover in coincidence with the well-known Protein Dynamical Transition. Structural rearrangements of biomolecules can trap hydration water molecules over length-scale larger than nearest neighbors distances. This causes a new hopping regime specific only of hydration water and already active at high temperature.
Camisasca, G., Iorio, A., Tenuzzo, L., Gallo, P. (2022). Slow Dynamics of Biological Water. In Springer Proceedings in Physics (pp.29-52). Springer Science and Business Media Deutschland GmbH [10.1007/978-3-030-80924-9_2].
Slow Dynamics of Biological Water
Camisasca G.;Tenuzzo L.;Gallo P.
2022-01-01
Abstract
Water hydrating biomolecules shows a more complex dynamical behavior when compared to the bulk. Its translational slow dynamics can be described by two mechanisms characterized by two well distinct time scales. One mechanism is the α -relaxation typical of supercooled bulk water and other glass forming liquids. Upon cooling, this relaxation shows a fragile-to-strong crossover due to the activation of hopping phenomena which permits to the water molecules in the hydration layer to escape from nearest neighbors cage. The second mechanism is a much slower relaxation that is present only in hydration water and it is coupled with the biomolecule dynamics. This long-relaxation shows upon cooling a strong-to-strong crossover in coincidence with the well-known Protein Dynamical Transition. Structural rearrangements of biomolecules can trap hydration water molecules over length-scale larger than nearest neighbors distances. This causes a new hopping regime specific only of hydration water and already active at high temperature.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
