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Cereal Chem 43:169 - 186.  |  VIEW ARTICLE

Determination of Molecular-Weight Distribution in Wheat-Flour Proteins by Extraction and Gel Filtration in a Dissociating Medium.

O. B. Meredith and J. J. Wren. Copyright 1966 by the American Association of Cereal Chemists, Inc. 

A solvent consisting of urea (3M), acetic acid (0.1M), and cetyltrimethylammonium bromide (0.01M) dissolved in water is useful for both extraction and chromatography of wheat-flour proteins. A clear extract, containing about 95% of the total proteins, is obtained by homogenization followed by centrifugation for 30 min. at 140,000 x g (max.). When the extract is chromatographed on a column of Sephadex G-200 an elution curve is obtained that appears to be a true profile of molecular-weight distribution; this can be calibrated with proteins of known molecular weight, isolated from other sources. Results of rechromatography and other evidence indicate that the elution curve does not reflect noncovalent aggregation of protein molecules. The elution curve contains four main peaks which are formed primarily, in order, by glutenins, gliadins, albumins, and nonproteins. Addition of mercaptoethanol to the extract nearly abolishes the glutenin peak and shifts the molecular-weight distribution to lower values. Experiments with sulfhydryl-blocking reagents indicate that neither the extraction method nor hand-milling of wheat induces a change in molecular-weight distribution by sulfhydryl-disulfide interchange.

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