Subunit composition of wheat glutenin proteins, isolated by gel filtration in a dissociating medium

Abstract

Proteins were extracted from wheat meal or flour in 0.1 M acetic acid, 3 M urea and 0.01 M CTAB and fractionated in columns of cross-linked Sepharose in the same solvent. An heterogeneous fraction of high molecular weight eluted from the column which, when reduced and subjected to SDS-polyacrylamide-gel electrophoresis, separated into 12 components. Their molecular weights ranged from about 31,500 to 136,000. The unreduced protein was insoluble in salt solutions and aqueous ethanol but soluble in 0.1 M acetic acid and was therefore defined as glutenin. Glutenins of different molecular weight were made up from the same subunits but in different proportions. The ethanol-soluble proteins (gliadins) of the flour were fractionated in Sephadex G-100. The protein component that was excluded from the Sephadex gel, often described as high-molecular-weight gliadin, was shown to contain 8 distinguishable subunits and they had identical mobilities to 8 of the 12 subunits of glutenin.