水和特性及び相転移挙動から探るトレハロースの生体物質保護機構

概要

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In this review we describe thermodynamic properties of small carbohydrates with an emphasis on characteristic aspects of α, α -trehalose, which are physicochemical background of its superior biological protective function. First, aqueous properties of small carbohydrates are discussed in terms of unfrozen water and partial molar isentropic compressibility, being related to their glass transition temperatures. It is argued for these thermodynamic parameters that there exists a common systematic dependency on molecular structures of carbohydrates. Next solid-state properties of α, α -trehalose are discussed in view of humid effects on its phase transition behavior. One of its known anhydrates, T_α, can be formed only under dry atmospheres, of which high hygroscopicity would contribute to avoiding the devitrification of the sugar glass induced by moisture uptake. Another interesting finding is that the anhydrate T_β is formed at as low as 95℃ under high humid atmospheres whereas dry or intermediate humid atmospheres give the anhydrate T_β over 160℃. A picture is provided, which depicts pathways to link various solid forms of trehalose with taking into account the humid effects.
2005-08-30