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Nakagawa, Hiroshi
Teion Seibutsu Kogakkai-Shi, 67(2), p.129 - 133, 2021/10
Water activity is an indication of the microbial growth, enzymatic activity, preservation, and quality of foods. The water activity of glycerol-water mixtures can be controlled by changing its ratio. In this study, the diffusive dynamics of water were investigated at various water activities by incoherent quasi-elastic neutron scattering. It was found that water activity dependent diffusive water dynamics is correlated with the water sorption isotherm.
Nakagawa, Hiroshi; Ajito, Satoshi
Teion Seibutsu Kogakkai-Shi, 66(2), p.83 - 92, 2021/02
Hydration and dehydration of bio-macromolecules result in the changes in the structural stabilization and biological functionality. The structure and dynamics of the hydration water are essential to understand the hydration and dehydration processes of the biosystem. Since neutron has wavelength in the order of angstrom and thermal energy, it is able to observe the structures and dynamics of the bio-molecules and hydration water. The large difference in neutron scattering cross-sections between hydrogen and deuterium provides powerful methods for emphasizing the scattering from a bio-macromolecule or hydration water by selective deuteration for hydrated biological materials. Incoherent neutron scattering and small-angle neutron scattering are able to examine the dynamics of the hydration water, and the density and structure of the hydration shell, respectively. The neutron sources, JRR-3 reactor and J-PARC accelerator, are available in Japan. The present review aims to provide the readers with brief descriptions of the neutron scattering methods and the applications to the protein hydration.
