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Isolation and Functionality Testing of Low Molecular Weight Glutenin Subunits

¹CSIRO Division of Plant Industry, GPO Box 1600, Canberra, ACT 2601 Australia. ²CSIRO Division of Plant Industry, North Ryde, NSW 2113 Australia. ³Corresponding author. E-mail: mail: J.Skerritt@pi.csiro.au Fax + 61 2 6246 5351/5000. Phone: + 61 2 6246 5350.

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.