Chitosan-Soyprotein Interaction as Determined by Thermal Unfolding Experiments
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Chitosan interaction with soybean β-conglycinin β<SUB>3</SUB> was investigated by thermal unfolding experiments using CD spectroscopy. The negative ellipticity of the protein was enhanced with rising solution temperature. The transition temperature of thermal unfolding of the protein (<I>T</I><SUB>m</SUB>) was 63.4 °C at pH 3.0 (0.15 <small>M</small> KCl). When chitosan was added to the protein solution, the <I>T</I><SUB>m</SUB> value was elevated by 7.7 °C, whereas the <I>T</I><SUB>m</SUB> elevation upon addition of chitosan hexamer (GlcN)<SUB>6</SUB> was 2.2 °C. These carbohydrates appear to interact with the protein stabilizing the protein structure, and the interaction ability could be evaluated from the <I>T</I><SUB>m</SUB> elevation. Similar experiments were conducted at various pHs from 2.0 to 3.5, and the <I>T</I><SUB>m</SUB> elevation was found to be enhanced in the higher pH region. We conclude that chitosan interacts with β-conglycinin through electrostatic interactions between the positive charges of the chitosan polysaccharide and the negative charges of the protein surface.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(7), 1786-1789, 2006-07-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry