DETERMINATION OF THE BINDING OF HEXANAL TO SOY GLYCININ AND BETA-CONGLYCININ IN AN AQUEOUS MODEL SYSTEM USING A HEADSPACE TECHNIQUE

The equilibrium binding of hexanal to soybean glycinin and beta-conglycinin has been evaluated under several conditions. Binding of the flavor ligand was allowed to approach saturation. In 0.3 M Tris, pH 8.0, glycinin and beta-conglycinin had similar affinities, 270 and 303 M-1, respectively. The numbers of binding sites for hexanal for glycinin and beta-conglycinin were 108 and 26, respectively. Different buffer conditions, 0.5 M NaCl with 0.02% NaN3 or 10 mM beta-mercaptoethanol, changed the number of binding sites and affinity for hexanal for these proteins. Positive cooperativity was observed for the binding of hexanal to both proteins. ANS surface hydrophobicity and turbidity increases suggested that structural changes may occur as a result of hexanal binding.