Simultaneous isolation of wheat high molecular weight and low molecular weight glutenin subunits

A procedure was established for isolating simultaneously high molecular weight (HMW-GS) and low molecular weight glutenin subunits (LMW-GS) from chloroform-defatted wheat flour. Temperature conditions were optimised to obtain maximum yield and purity. A pre-extraction of gliadin was performed with 50% (v/v) propan-1-ol at room temperature. Glutenin subunits were solubilised from the residue at 60 degrees C with 50% (v/v) propan-1-ol containing 1% (w/v) dithiothreitol. The HMW-GS in the glutenin mixture were then precipitated selectively by increasing the propan-1-ol concentration to 60%. Upon addition of propan-1-ol to a final concentration of 85%, LMW-GS were precipitated. It was shown by densitometric scanning of SDS-PAGE gels that the isolated glutenin subunits were very pure. Furthermore, a partial separation of LMW-GS into B and C type subunits was observed when the propan-1-ol concentration was increased gradually. (C) 1998 Academic Press.