Cereal Chem 49:416 - 429.  |  VIEW ARTICLE
Wheat Gluten Subunits: Molecular Weights Determined by Sodium Dodecyl Sulfate- Polyacrylamide Gel Electrophoresis.

J. A. Bietz and J. S. Wall. Copyright 1972 by the American Association of Cereal Chemists, Inc. 

Polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulfate (SDS) has revealed the number and molecular weight (MW) of the different-sized subunits obtained from gliadin and glutenin after reduction of disulfide bonds. Most proteins in gliadin are single-chained, and have MW's near 36,500. The whole gliadin fraction also contains 11,400-MW polypeptides which may be albumins, a major polypeptide of MW 44,200, and omega-gliadins of MW's 69,300 and 78,100; trace amounts of other polypeptides are also present. The 44,200-MW polypeptides, along with some of MW 36,500, are joined through disulfide bonds into higher-MW proteins. Glutenin consists of polypeptides of at least 15 unique MW's ranging from 11,600 to 133,000; two glutenin subunits correspond in mobility to the major gliadin polypeptides. Since disulfide cleavage and denaturation are complete and since no other labile cross-links can be detected, these polypeptides may represent the fundamental structural units of glutenin. Equilibrium-dialysis data establish that the amounts of SDS bound to gluten proteins and standards are similar, supporting the MW values obtained for gliadin and glutenin. In addition to determining MW distribution and number of gluten subunits, SDS-polyacrylamide gel electrophoresis can monitor column separations, serve as a criterion of purity, and detect differences in subunit composition of glutenins of different varieties.