A A C C   2 0 0 0   A n n u a l   M e e t i n g

The HMW subunits of glutenin represent one of the most intensively studied groups of wheat storage proteins, the interest arising from the correlation of certain subunit alleles with bread-making quality in European wheats. Despite intensive study we still do not understand the mechanisms of elasticity or the differences between the association with quality behaviour of the subunits. We have been using stress-strain studies of cross-linked HMW subunits to determine bulk elastic properties, and atomic force microscopy (AFM) to determine the force curves of individual HMW subunits and covalently (disulfide-bonded) and non-covalently bonded HMW subunit networks. The interactions of the subunits have been studied using AFM to image networks formed by the subunits and FT-IR to determine the secondary structures present. The central repetitive domains of the subunits have been studied in whole subunits (1Dx5), heterologously expressed peptides corresponding to the central domain of subunit 1Dx5 and 'perfect repeat' peptides. These structural studies indicate that the 'perfect repeat' peptides form higher contents of inter-molecular beta sheet structure than either the whole subunit or the central domain peptide. The results are discussed in relation to our knowledge of the structures of the central repetitive domains of the HMW subunits.