Cereal Chem 72:450-456 |
Changes in Some Physicochemical Properties of Flour Proteins Due to Partial Reduction with Dithiothreitol.
H. R. Kim and W. Bushuk. Copyright 1995 by the American Association of Cereal Chemists, Inc.
Changes in protein solubility, patterns of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS- PAGE), and weight of SDS-insoluble gel protein and its rheological properties during reduction of wheat flour proteins by dithiothreitol (DTT) were investigated for two Canadian hard red spring wheats of diverse strength. SDS-PAGE results for the water-soluble protein fraction showed that changes in solubility and gel protein properties with gradually increasing reduction resulted from increasing differential release of water- soluble glutenin oligomers (fragments of polymeric glutenin comprising several subunits). Oligomers contained mainly y-type high Mr glutenin subunits (8 and 10 for Glenlea and 9 and 10 for Katepwa) or B- type low Mr glutenin subunits. The protein of Katepwa flour (strong) released water-soluble oligomers at a lower DTT concentration than did the protein of Glenlea (extra strong). With increasing DTT concentration, the amount of the y-type subunits (indicated by SDS-PAGE band intensity) and the solubility of total protein in SDS solution increased, whereas the gel protein weight and its elasticity decreased. The results showed that the proteins of the extra strong Glenlea flour were more resistant to reduction by DTT than were the proteins of the weaker Katepwa flour. The implication of these results in the molecular basis of wheat flour strength for breadmaking is discussed.