Sugars decrease the thermal denaturation and aggregation of arachin

Abstract

The effect of three sugars D‐xylose, D‐glucose and D‐sucrose (with increasing hydroxyl content) on the thermal denaturation and protein‐protein interactions of arachin at pH 3.6 were studied by various physicochemical techniques. These included gel melting temperature, turbidity, electrophoresis, viscosity, u.v. difference, fluorescence and circular dichroic measurements. Sugars decreased the heat‐induced aggregation of arachin as shown by the gel melting temperature, turbidity and electrophoretic measurements. Arachin became more compact in the presence of sugars as shown by the reduced viscosity, u.v. difference and fluorescence spectral measurements. Far u.v.‐CD spectral measurements suggested that sugars increase the ordered structure. Viscosity and spectral measurements also showed that heating and cooling in the presence of sugars at pH 3.6 decrease the thermal unfolding of arachin. The effectiveness of the sugar to bring about all the described changes increased with its hydroxyl content. The preventive effect of sugars on the thermal denaturation and aggregation of arachin probably arises from their capacity to strengthen the intra‐protein hydrophobic and hydrogen bonding.