8 Conformational studies of HMW subunit 1Dx5 and derived peptides.

A. S. TATHAM (1), S. M. Gilbert (1), K. Feeney (1), K. Wellner (2), and P. R. Shewry (1). (1) IACR-Long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Bristol BS41 9AF, UK; (2) Institute of Food Research, Norwich Laboratory, Norwich Research Park, Norwich NR4 7UA, UK.

The conformations of HMW subunit 1Dx5 and of heterologously expressed and synthetic peptides corresponding to different lengths of the repetitive domain were studied by Fourier tranform infrared (FT- IR) and circular dichroism (CD) spectroscopy. FT-IR can give information on secondary structures at low moisture contents and was used to compare the effects of hydration on the whole subunit, a 58kD peptide corresponding to the repetitive domain and smaller peptides. Most structural changes appeared to occur in the repetitive domain. At low moisture contents there were high contents of inter-molecular beta-sheet, at higher moisture contents more beta-turns and less beta-sheet structures. CD was used to determine and compare the structural stability and changes on heating and cooling of subunit 1Dx5 and derived peptides of varying size. These changes in structure and interactions may relate to the rheological properties of gluten and dough systems.