6. The Effect of Surface Active Agents on the Hydration of Protein(Papers presented at the 35th Annual Meeting, April, 1989, Tokyo)

Abstract

The characteristic of hydration water of ovalbumin with some surfactants was investigated. Recently, it was reported that non-ionic surfactants had excellent ability to protect the protein against the denaturation by freeze-thawing. To compare the mechanism of protection with other protectants such as sugars, polyols and amino acids, the alterations of the amount of unfrozen water, the extent of the interaction of unfrozen water and the protein were examined using ^1HNMR. Non-ionic surfactants decreased the amount, reduced self-diffusion coefficient D, and increased the rotational molecular correlation time τ_c of unfrozen water. Ionic surfactants did not show such effects. These results suggest non-ionic surfactants are substituted for some of hydration water of the protein with the polar head group and strengthen the interaction of hydration water and protein. It seems the mechanism of protection is similar with non-ionic surfactants and other protectants such as sugars.