Isolation and Functionality Testing of Low Molecular Weight Glutenin Subunits

Various protein fractionation techniques have been applied to the isolation and purification of milligram quantities of low molecular weight glutenin subunits (LMW‐GS). No single technique was applicable to the purification of the majority of the subunits. Partial purification of certain LMW‐GS was obtained using ion‐exchange chromatography and reversedphase HPLC. Preparations containing α‐ and γ‐type subunit sequences did not strengthen dough when incorporated into a base flour, whereas preparations containing a subunit with an N‐terminal methionine residue (METSHIPGL‐) did. Using preparative isoelectric focusing over a narrow pH range, it was possible to purify (to ≈90% purity) a B subunit that also had the N‐terminal sequence of METSHIPGL‐. This polypeptide, when incorporated into a base flour, had a dough strengthening effect in mixing trials, but less so than an equivalent amount of a high molecular weight glutenin subunit.