Tea is one of the most widely-consumed beverages in the world, and has been studied extensively for its putative benefits to human health. (-)-Epigallocatechin-3-gallate (EGCG), a major phenolic constituent of tea, has demonstrated biological activity against major inflammatory pathways and hypersensitivity disorders, as well as the ability to alleviate symptoms of food allergies and intolerances. One proposed mechanism of this effect is sequestration and structural modification of immunostimulatory proteins as a result of direct interactions with EGCG. Recent studies in our lab have demonstrated the ability of dietary polyphenols, including EGCG, to interact with a2-gliadin (57 – 89), a 33-amino acid peptide responsible for the stimulation of the adaptive immune response associated with celiac disease. The present work characterizes the impact of these interactions on the structural confirmation of the 33-mer, which adapts a natively unfolded structure with polyproline II helix motifs. This characteristic structure allows recognition and preferential binding of the peptide by antigen presenting cells in individuals with celiac disease, initiating the onset of the adaptive immune response associated with the disease. Circular dichroism experiments show that the 33-mer undergoes conformational changes in the presence of excess EGCG. This response is corroborated by NMR data wherein chemical shift perturbation of both 1H and 13C signals allows for the elucidation of interaction sites on the peptide. The size and stability of the 33-mer/EGCG complexes formed were also characterized by dynamic light scattering and differential scanning calorimetry.

Structural modification of an immunodominant gluten peptide upon interaction with (-)-epigallocatechin-3-gallate

251st National Meeting (2016)

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