Cereal Chem 69:535-541   |  VIEW ARTICLE

Composition of High-Molecular-Weight Glutenin Subunit Dimers Formed by Partial Reduction of Residue Glutenin.

W. E. Werner, A. E. Adalsteins, and D. D. Kasarda. Copyright 1992 by the American Association of Cereal Chemists, Inc. 

Partial reduction of residue (glutenin) proteins remaining after extraction of flour with sodium dodecyl sulfate (SDS) solution produced soluble monomers, dimers, and possibly trimers of high-molecular-weight glutenin subunits (HMW-GS) and monomers of low-molecular-weight glutenin subunits as indicated by SDS-polyacrylamide gel electrophoresis (PAGE). The partially reduced proteins were soluble in the dithiothreitol-Tris buffer (pH 8.5), lacking SDS, that was used to reduce the residue proteins. The disulfide- linked subunits in the dimers were analyzed by two-dimensional SDS-PAGE with reducing agent present only in the second dimension. The two-dimensional analyses indicated that pairs consisting of an x-type and a y-type HMW-GS predominated in the dimers produced at low levels of reducing agent (for example, 0.5 mM dithiothreitol). Dimers composed only of x-types were sometimes observed, particularly at higher levels of reducing agent. No dimers combining only y-type HMW-GS were noted. The faster SDS-PAGE mobilities of y-type monomers relative to the mobilities of the equivalent, completely reduced forms indicated a more compact structure for the partially reduced forms, presumably due to the presence of at least one intramolecular disulfide bond. The intramolecular disulfide bonds of the y-type HMW-GS monomers and the combinations of HMW-GS in the dimers of HMW-GS are likely to reflect arrangements found in native glutenin.