Cereal Chem. 71:242-247   |  VIEW ARTICLE


Disaggregation of Glutenin with Low Concentrations of Reducing Agent and with Sonication: Solubility, Electrophoretic, and Scanning Electron Microscopy Studies.

K. Khan, L. Huckle, and T. Freeman. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

Doughs obtained from a hard red spring wheat flour (Len) were mixed in a farinograph, with and without the reducing agent dithiothreitol (DTT), and freeze-dried. The proteins from the dough were extracted. The proteins from Len flour were also extracted using sonication. Solubility of the proteins increased markedly from about 82% in the control to about 95-100% for both the sonicated and DTT- treated samples. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the protein extracts with and without reducing agent of both farinograph-mixed and sonicated procedures showed an increase in the amount of glutenin aggregates with lower molecular weight that remained at the 12% resolving gel origin and a concomitant decrease of the high molecular weight glutenin aggregates at the 4% stacking gel origin as DTT concentration or sonication time increased. The portion of the gel showing heavy streaking, where the high molecular weight subunits usually appear, was cut out and eluted with sample solvent containing reducing agent. SDS-PAGE of the eluted samples under reducing conditions revealed that both the DTT- treated and the sonicated samples contained high molecular weight subunits of glutenin resulting from the proteins that caused the streaking. Scanning electron micrographs of the DTT-treated doughs revealed major alterations in the protein matrix network as DTT concentration was increased, even though SDS- PAGE of unreduced extracts did not reveal high molecular weight glutenin subunits. These results indicate that the larger glutenin protein aggregates can be dissociated into smaller aggregates without release of monomeric high molecular weight glutenin subunits, thereby affecting rheological and breadmaking properties.