Cereal Chem 69:475-480   |  VIEW ARTICLE

Isolation and Fractionation of Carbohydrate-Containing Proteins from Wheat Gluten.

J. Chen, K. Khan, D. R. Shelton, and B. L. D'Appolonia. Copyright 1992 by the American Association of Cereal Chemists, Inc. 

Examination of the carbohydrates of hard red spring wheat gluten showed that the levels of carbohydrate in three fractions, sodium dodecyl sulfate (SDS)-insoluble, SDS-soluble-70% ethanol-insoluble, and SDS- soluble-70% ethanol-soluble, were 11.63, 1.27, and 0.5% (w/w), respectively. The major sugars in the SDS- insoluble fraction were glucose, xylose, and arabinose; galactose and mannose were present in lesser amounts. The SDS-soluble fractions contained glucose, galactose,and mannose as the major sugars. The ethanol-insoluble fractions contained more sugars than the ethanol-soluble fractions for each neutral sugar component. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of the three protein fractions demonstrated that the carbohydrate was associated with all protein subunits with molecular mass greater than 32,000 Da. The carbohydrate-containng fractions isolated by an SDS solubility fractionation procedure were further fractionated by gel filtration chromatography on Sephadex G-200 and Sephacryl S-400. The carbohydrate components of the SDS-soluble-70% ethanol-insoluble and SDS-soluble-70% ethanol-soluble fractions were associated with the high molecular weight subfaction obtained by gel filtration chromatography. Coincident stains for carbohydrate and protein after electrophoresis of the protein fractions indicated that these components were closely associated. The glucose in wheat gluten resulted mainly from endosperm starch, whereas other nonstarchy carbohydrate may be involved in the glycoprotein structure of wheat gluten.