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Electrophoretic Behaviors of α-Lactalbumin and β-Lactoglobulin Mixtures Caused by Heat Treatment

  • Lee, You-Ra (Department of Food and Nutrition and Human Ecology Research Institute, Chonnam National University) ;
  • Hong, Youn-Ho (Department of Food and Nutrition and Human Ecology Research Institute, Chonnam National University)
  • Received : 2002.08.02
  • Accepted : 2003.03.21
  • Published : 2003.07.01

Abstract

In order to study the reaction behaviors of bovine $\alpha$-lactalbumin ($\alpha$-La), $\beta$-lactoglobulin ($\beta$-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-$\alpha$-La increased as temperature increased, and that the loss of apo-$\alpha$-La was slightly higher than that of holo-$\alpha$-La. The tests also showed that during heat treatment, a mixture of $\alpha$-La and $\beta$-Lg was less stable than $\alpha$-La alone. As such, it was assumed that $\beta$-Lg induced holo-$\alpha$-La to be less stable than apo-$\alpha$-La during heat treatment. The reaction behavior of $\alpha$-La (holo-, apo-form) during heat treatment showed similar patterns in the 2-D-PAGE electropherogram, but the mixture of $\alpha$-La and $\beta$-Lg created new bands. In particular, the results showed a greater loss of native $\alpha$-La in the holo-$\alpha$-La and $\beta$-Lg mixture than in the apo-$\alpha$-La and $\beta$-Lg mixture. Thus, it can be concluded that the holo-$\alpha$-La and $\beta$-Lg mixture was more intensively affected by heat treatment than other samples, and that free sulphydryl groups took part in the heat-induced denaturation.

Keywords

$\alpha$-lactalbumin;$\beta$-lactoglobulin;Heat Treatment;Electrophoresis;2-D PAGE;SH Group

Acknowledgement

Supported by : Chonnam National University

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