Separation of durum wheat proteins by ultrathin-layer isoelectric focusing: a new tool for the characterization and quantification of low molecular weight glutenins.

An isoelectric focusing method capable of resolving all groups of storage protein of the wheat seed, including the most basic low molecular weight glutenin (LMWG), was developed. Ultrathin polyacrylamide gels were used after drying and rehydration with 8 M urea, 50 mM DTE and 2.4% carrier ampholytes (pH 4-9). Densitometric scanning of the isoelectric focusing gels permitted a more accurate and specific quantitation of LMWG components among various cultivars than patterns based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The two main genetic types (i.e. 'gamma-42' and 'gamma-45') of durum wheats were separated on the basis of the proportion in LMWG in storage proteins, but no significant difference was found within these groups. Advantages of the system as regards reliability, high resolution, ability to abolish protein oxidation and preventing reaggregation of LMWG were also discussed.