Quantitation of the immunodominant 33-mer peptide from α-gliadin in wheat flours by liquid chromatography tandem mass spectrometry.
Coeliac disease (CD) is triggered by the ingestion of gluten proteins from wheat, rye, and barley. The 33-mer peptide from α2-gliadin has frequently been described as the most important CD-immunogenic sequence within gluten. However, from more than 890 published amino acid sequences of α-gliadins, only 19 sequences contain the 33-mer. In order to make a precise assessment of the importance of the 33-mer, it is necessary to elucidate which wheat species and cultivars contain the peptide and at which concentrations. This paper presents the development of a stable isotope dilution assay followed by liquid chromatography tandem mass spectrometry to quantitate the 33-mer in flours of 23 hexaploid modern and 15 old common (bread) wheat as well as two spelt cultivars. All flours contained the 33-mer peptide at levels ranging from 91-603 μg/g flour. In contrast, the 33-mer was absent (<limit of detection) from tetra- and diploid species (durum wheat, emmer, einkorn), most likely because of the absence of the D-genome, which encodes α2-gliadins. Due to the presence of the 33-mer in all common wheat and spelt flours analysed here, the special focus in the literature on this most immunodominant peptide seems to be justified.
Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut, Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Kathrin
K
Schalk
Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut, Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Christina
C
Lang
Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut, Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Herbert
H
Wieser
Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut, Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Peter
P
Koehler
Deutsche Forschungsanstalt für Lebensmittelchemie, Leibniz Institut, Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Katharina Anne
KA
Scherf
D002853:Chromatography, Liquid; D005433:Flour; D005903:Gliadin / Q000737:chemistry* / Q000276:immunology; D016056:Immunodominant Epitopes / Q000737:chemistry / Q000276:immunology; D010455:Peptides / Q000737:chemistry* / Q000276:immunology; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry; D014908:Triticum / Q000737:chemistry*
D016056:Immunodominant Epitopes; D010455:Peptides; D005903:Gliadin