By extraction of wheat flour with sodium dodecyl sulfate (SDS) solution at pH 6.8, about 76% of the total flour nitrogen solubilized into clear supernatant. This solvent was more effective for extraction of wheat protein than 0.01M acetic acid, aluminium lactate-lactic acid buffer (pH 3.1), AUC-solvent (0.1M acetic acid, 3M urea and 0.01M cetyltrimethylammonium bromide) and 3, 5-diiodosalicylic acid lithium salt etc. The molecular weight distribution of the SDS-soluble proteins was studied by SDS-polyacrylamide gel electrophoresis and by molecular sieve chromatography on controlled pore glass (CPG-10-500) without prior reduction of disulfide linkages of the proteins. Most of the SDS-soluble proteins had molecular weight of less than 75, 000, suggesting single-chained proteins. A small amount of relatively high molecular weight proteins which contained intermolecular disulfide linkages was also detected in the gel of electrophoresis, while high molecular weight protein which did not migrate into gel matrix during electrophoresis without prior reduction of disulfide linkages existed in trace amount in the SDS-soluble fraction.
The SDS-insoluble proteins were almost completely extracted by further extraction with SDS in combination with 2-mercaptoethanol or with mercuric chloride.

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