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β Structure motif recognition by anti‐gliadin antibodies in coeliac disease
Author(s) -
Alfonso Patricia,
Soto Claudio,
Albar Juan Pablo,
Camafeita Emilio,
Escobar Héctor,
Suárez Lucrecia,
Rico Manuel,
Bruix Marta,
Méndez Enrique
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00388-3
Subject(s) - gliadin , peptide , coeliac disease , circular dichroism , chemistry , antibody , polyclonal antibodies , turn (biochemistry) , peptide sequence , biochemistry , biology , gluten , immunology , medicine , disease , gene
A 20‐amino acid synthetic peptide from the N‐terminal region of γ3 avenin yields a surprisingly strong reactivity with anti‐gliadin antibodies (AGA) of coeliac sera, comparable to that of a gliadin extract. In contrast, a low reactivity is observed with five similar peptides derived from α‐gliadin, γ70 and ω1 secalins. Circular dichroism studies of these peptides show that the avenin peptide displays the highest β‐turn content (30%), while other peptides yield much lower values. In agreement with circular dichroism data, nuclear magnetic resonance data point to the presence of a β‐turn in the avenin peptide DPSEQ segment, a sequence with a high statistical β‐turn preference. A strong linear dependence between AGA reactivity and β‐turn content was observed for these peptides, indicating for the first time a role of β‐turn motifs in anti‐gliadin antibodies recognition in coeliac disease. This suggests that circulating AGA in coeliac patients comprise not only linear but also conformational antibodies against β‐turn motifs. Polyclonal antibodies raised against the avenin peptide containing β‐turn motifs react by immunoblotting with all gliadin, hordein and secalin proteins, which are rich in β‐turn conformations, despite that their primary structures are unrelated to that of the peptide.