Stability of beta-lactoglobulin A in the presence of sugar osmolytes estimated from their guanidinium chloride-induced transition curves.

The stabilizing role of Trehalose, Sucrose, Sorbitol and Mannitol as sugar osmolytes and polyols on beta-lactoglobulin A (beta-lgA) against its chemical denaturation at pH 2.0 and 25 degrees C has been explored by means of UV-vis spectroscopy. It has been observed that DeltaG (D) (o) of beta-lgA in the presence of 10% (w/v) Trehalose, Sucrose, Sorbitol and Mannitol is increased. We report that the functional dependence of DeltaG (D) of proteins in the absence and the presence of sugar osmolytes on denaturant concentration is linear. Trehalose is found to induce remarkable stability of beta-lgA against chemical denaturation. Furthermore, we assumed sugar osmolytes do not affect the secondary and tertiary structures of the native and GdnHCl-denatured states.