New exploration of the γ-gliadin structure through its partial hydrolysis.

Sahli, Line; Boire, Adeline; Solé-Jamault, Véronique; Rogniaux, Hélène; Giuliani, Alexandre; Roblin, Pierre; Renard, Denis

The partial enzymatic hydrolysis of wheat gliadins constitutes an interesting tool to unravel their structural specificity. In this work, the structure and conformation of γ-gliadin were investigated through its limited chymotrypsic digestion. Using a combination of computational, biochemical and biophysical tools, we studied each of its N and C terminal domains. Our results reveal that γ-gliadin is a partially disordered protein with an unfolded N-terminal domain surprisingly resistant to chymotrypsin and a folded C-terminal domain. Using spectroscopic tools, we showed that structural transitions occured over the disordered N-terminal domain for decreasing ethanol/water ratios. Using SAXS measurements, low-resolution 3D structures of γ-gliadin were proposed. To relate the repeated motifs of the N-terminal domain of γ-gliadin to its structure, engineered peptide models PQQPY/F were also studied. Overall results demonstrated strong similarities between the N-terminal domain and its derived model peptides. Our findings support the use of these peptides as general templates for understanding the wheat protein assembly and dynamics.