title: Chitosan-soyprotein interaction as determined by thermal unfolding experiments.
abstract: Chitosan interaction with soybean beta-conglycinin beta(3) 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 (T(m)) was 63.4 degrees C at pH 3.0 (0.15 M KCl). When chitosan was added to the protein solution, the T(m) value was elevated by 7.7 degrees C, whereas the T(m) elevation upon addition of chitosan hexamer (GlcN)(6) was 2.2 degrees C. These carbohydrates appear to interact with the protein stabilizing the protein structure, and the interaction ability could be evaluated from the T(m) elevation. Similar experiments were conducted at various pHs from 2.0 to 3.5, and the T(m) elevation was found to be enhanced in the higher pH region. We conclude that chitosan interacts with beta-conglycinin through electrostatic interactions between the positive charges of the chitosan polysaccharide and the negative charges of the protein surface.
authors.affiliation: Department of Advanced Bioscience, Kinki University, Nara 631-8505, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Morita
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Saito
authors.forename: Wataru
authors.initials: W
authors.lastname: Kugimiya
authors.forename: Tamo
authors.initials: T
authors.lastname: Fukamizo
mesh_terms: D052179:Antigens, Plant; D048271:Chitosan / Q000737:chemistry*; D002942:Circular Dichroism; D005916:Globulins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011485:Protein Binding; D017510:Protein Folding; D055314:Seed Storage Proteins; D030262:Soybean Proteins / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013696:Temperature; D013816:Thermodynamics
chemical_list: D052179:Antigens, Plant; D005916:Globulins; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; D048271:Chitosan