Molecular weights of high molecular weight subunits of glutenin determined by mass spectrometry

High molecular weight (HMW) subunits of glutenin, corresponding to those for which full length gene sequences are available, were purified and their M_rs determined by mass spectrometry [matrix-assisted laser desorption ionisation (MALDI)]. In general, the M_rs determined were within the experimental error of the techniques employed [at the mass range of the high molecular weight (hmw) prolamins, error ∼ 500 Da]. Two subunits, 1 Dx2 and 1By9, however, showed M_rs approximately 900 Da higher and 1700 Da lower, respectively, than expected from their gene sequences. These data confirm that the HMW subunits are not extensively glycosylated and also demonstrate the utility of mass spectrometry for determining the M_rs of prolamins.