Identity of SDS-insoluble Proteins with Purified Glutenin from Wheat Flour

Sodium dodecyl sulfate (SDS)-insoluble proteins from wheat flour were solubilized by the reduction of their disulfide linkages with 2-meracaptoethanol. The polypeptide compositions of the reduced SDS-insoluble proteins were compared with those of the reduced glutenin by SDS-polyacrylamide gel electrophoresis, isoelectric focusing and amino acid analysis. SDS-polyacrylamide gel electrophoretic patterns of the reduced SDS-insoluble proteins almost coincided with those of the reduced glutenin. Seven major bands (Band 1–7) were obtained from both samples of the reduced proteins. These protein bands were subjected to analysis of amino acid compositions and isoelectric focusing, and similarities between polypeptides of the SDS-insoluble proteins and the glutenin were observed in their amino acid compositions and isoelectric focusing patterns. The results obtained suggested that the preparation of the reduced SDS-insoluble proteins might be used as a simple and rapid method to obtain the glutenin subunits.