SALT-INDUCED DISAGGREGATION SOLUBILIZATION OF GLIADIN AND GLUTENIN PROTEINS IN WATER/

The effect of salt concentration used in preparing gluten, on the subs equent dissolution of gluten in water, was examined. Flour from a Cana dian hard red spring wheat cultivar, Katepwa, was used to prepare glut ens using three different solvents, i.e. distilled deionized water (DD W), 0.2% NaCl solution and 2% NaCl solution. The isolated wet glutens were extracted sequentially with DDW, providing four water soluble fra ctions and an insoluble residue. The amount of protein in each fractio n was determined and respective compositions were assessed electrophor etically under reducing and non-reducing conditions. Surprisingly, DDW extracts of gluten prepared with 2% NaCl contained almost all the gli adins, except some omega-gliadin components, and most of the polymeric glutenin. For the gluten prepared with 0.2% NaCl, most of the gliadin , but only a small portion of glutenin, was extracted. For gluten prep ared with DDW, only part of the gliadins and almost no glutenin was ex tractable with water. The DDW solubilities of gluten proteins prepared in DDW, 0.2% NaCl and 2% NaCl were 27, 52, and 85%, respectively, aft er four sequential extracts with DDW. The large increases in the solub ility of gliadin and glutenin proteins in DDW when the gluten is prepa red in salt solution (after removal of most of the salt) can be explai ned on the basis of a salt-induced conformational change of the protei ns, which renders water a more effective solvent. (C) 1996 Academic Pr ess Limited