DisplayTitle

Influence of Salts and Aggregation of Gluten Proteins on Reduction and Extraction of High Molecular Weight Glutenin Subunits of Wheat¹

¹Cooperative investigations, U.S. Department of Agriculture, Agricultural Research Service and the Department of Grain Science and Industry, Kansas State University. Contribution 98-2-J, Department of Grain Science and Industry, Kansas State Agricultural Experiment Station, Manhattan, KS 66506. ²Research assistant and adjunct professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ³Research chemist, USDA-ARS, Grain Marketing and Production Research Center, Manhattan, KS 66502. Mention of trademark or proprietary products does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. ⁴Corresponding author. E-mail: george@usgmrl.ksu.edu

High-molecular weight glutenin subunits (HMW-GS) of wheat were extracted by various combinations of reducing agents, salt solutions, and solvents. Preferential extraction of 1D-encoded HMW-GS occurred when flours were extracted with Tris-HCl SDS buffer at pH 6.8 containing 6% mercaptoethanesulfonic acid sodium salt (MESNA) and analyzed by SDS-PAGE. Similar effects were also found when dithiothreitol or β-mercaptoethanol were used in conjunction with nonchaotropic salts. If flours were first extracted with 50% 1-propanol, the extraction procedure yielded all HMW-GS, even in the presence of MESNA or high levels of salts. Addition of alcohols or chaotropes to the Tris buffer solutions containing MESNA or of solutions containing salt also extracted all HMW-GS. The HMW-GS reported most important in baking quality were found preferentially extracted by nonchaotropic salts and reducing agents. This is related to gluten aggregation and the gliadin-glutenin interaction and structure.