Cereal Chem 48:469 - 477. | VIEW
Evidence for Glutenin in Wheat: Stability Toward Dissociating Forces.
F. R. Huebner and J. A. Rothfus. Copyright 1971 by the American Association of Cereal Chemists, Inc.
The hypothesis that glutenin is an artifact of classic isolation procedures was examined by extraction of wheat proteins into urea solutions of phenol-acetic acid-water mixtures and by gel filtration of glutenin after sonication. After extraction of flour with water and then 2M urea, nitrogen recovered in dialyzed extracts and in the starch residue totaled 127% of that originally in the flour; 43% remained in the residue. Lyophilization and redialysis of all urea extracts and the residue lowered nitrogen recovery to 98% with 34% remaining in the residue. Nitrogen in the residue was reduced to 17% of the original amount by further extraction with 0.2N acetic acid. Subsequent treatment of the residue with mercaptoethanol and acrylonitrile and extraction with dilute acetic acid left less than 6% of the nitrogen insoluble. Gel filtration and gel electrophoresis showed that all urea extracts contained glutenin-like material along with low-molecular- weight proteins. Final extractions with dilute acetic acid removed glutenin with only a trace of gliadin. Ultrasonics dissociated glutenin and made it tractable enough to be separated on agarose columns in urea buffer at pH 9.2. The results support the contention that glutenin is highly aggregated and different from gliadin. The data show that urea extraction does not remove all protein from wheat flour.