The conformation of wheat gluten proteins in their functional hydrated solid state (doughy state) has been studied for the first time using attenuated total reflection infrared spectroscopy. The amide I band of functional gluten proteins reveals that, in addition to β-turns and α-helices, these proteins contain a significant amount of intra- and intermolecular extended β-sheet structures. It appears that the solubilization of gluten proteins results in a major decrease of the amount of β-sheet structures accompanied by an increase of the content of the β-turn and α-helical conformations. In addition, the α-helices appears to be more distorded in solution than in the functional state. Furthermore, spectra of ω- and γ-gliadins, which are two types of prolamins of differing amino acid sequence and conformation, confirm the results obtained on the functional protein system. These results suggest that viscoelastic gluten proteins may interact through aligned β-sheets corresponding to their repetitive domains.
