Addition of sugars such as sucrose
to aqueous protein solutions
generally stabilizes proteins against thermal denaturation by preferential
exclusion of sugars from proteins (preferential hydration of proteins).
In this study, we investigated the effect of sucralose, a chlorinated
sucrose derivative, on protein stability and preferential solvation.
Circular dichroism and small-angle X-ray scattering measurements showed
that sucrose increased the denaturation temperature of myoglobin and
was preferentially excluded from the protein, whereas sucralose decreased
the denaturation temperature of myoglobin and was preferentially adsorbed
to the protein. No clear evidence was obtained for the indirect effects
of sucralose on protein destabilization via the structure and properties
of solvent water from the physicochemical properties (mass density,
sound velocity, viscosity, and osmolality) of aqueous sucralose solutions;
therefore, we concluded that a direct protein–sucralose interaction
induced protein destabilization.