Conformational stability of digestion-resistant peptides of peanut conglutins reveals the molecular basis of their allergenicity

Danijela Apostolovic, Dragana Stanic-Vucinic, Harmen H. J. de Jongh, Govardus A. H. de Jong, Jelena Mihailovic, Jelena Radosavljevic, Milica Radibratovic, Julie A. Nordlee, Joseph L. Baumert, Milos Milcic, Steve L. Taylor, Nuria Garrido Clua, Tanja Cirkovic Velickovic, Stef J. Koppelman

Conglutins represent the major peanut allergens and are renowned for their resistance to gastro-intestinal digestion. Our aim was to characterize the digestion-resistant peptides (DRPs) of conglutins by biochemical and biophysical methods followed by a molecular dynamics simulation in order to better understand the molecular basis of food protein allergenicity. We have mapped proteolysis sites at the N- and C-termini and at a limited internal segment, while other potential proteolysis sites remained unaffected. Molecular dynamics simulation showed that proteolysis only occurred in the vibrant regions of the proteins. DRPs appeared to be conformationally stable as intact conglutins. Also, the overall secondary structure and IgE-binding potency of DRPs was comparable to that of intact conglutins. The stability of conglutins toward gastro-intestinal digestion, combined with the conformational stability of the resulting DRPs provide conditions for optimal exposure to the intestinal immune system, providing an explanation for the extraordinary allergenicity of peanut conglutins.