Effect of Calcium Binding on Thermal Denaturation of Bovine α-Lactalbumin

Abstract

The role of calcium in thermal behavior of bovine a-lactalbumin in the region of pH 2.5 to 6.5 was studied by differential scanning calorimetry with model solutions of a-lactalbumin in simulated milk uhrafihrate. When .1 M ethylenediaminetetraacetate was used to chelate the calcium 2 +, major effects were an average decrease of 20C of denaturation temperature, significant reduction of enthalpy of denaturation in simulated milk uhrafihrate, and loss of ability of protein to regain its original tertiary structure. Calcium binding appeared to be essential for stabilization of ~-lactalbumin.