SIMULTANEOUS ISOLATION OF WHEAT HIGH-MOLECULAR-WEIGHT AND LOW-MOLECULAR-WEIGHT GLUTENIN SUBUNITS

A procedure was established for isolating simultaneously high molecula r weight (HMW-GS) and low molecular weight glutenin subunits (LMW-GS) from chloroform-defatted wheat flour. Temperature conditions were opti mised 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 f inal concentration of 85%, LMW-GS were precipitated. It was shown by d ensitometric scanning of SDS-PAGE gels that the isolated glutenin subu nits 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.