In order to study the reaction behaviors of bovine a-lactalbumin (a-La), b-lactoglobulin (b-Lg), and their mixtures during heat treatment, samples were analyzed using native-polyacrylamide gel electrophoresis (Native-PAGE), sodium dodecylsulfate (SDS)-PAGE, and two-dimensional (2-D)-PAGE. The electrophoresis demonstrated that the loss of native-a-La increased as temperature increased, and that the loss of apo-a-La was slightly higher than that of holo-a-La. The tests also showed that during heat treatment, a mixture of a-La and b-Lg was less stable than a-La alone. As such, it was assumed that b-Lg induced holo-a-La to be less stable than apo-a-La during heat treatment. The reaction behavior of a-La (holo-, apo-form) during heat treatment showed similar patterns in the 2-D-PAGE electropherogram, but the mixture of a-La and b-Lg created new bands. In particular, the results showed a greater loss of native a-La in the holo-a-La and b-Lg mixture than in the apo-a-La and b-Lg mixture. Thus, it can be concluded that the holo-a-La and b-Lg mixture was more intensively affected by heat treatment than other samples, and that free sulphydryl groups took part in the heat-induced denaturation. |