Discovery of Physiologically Rele vant Gluten Peptides in Wheat, Barley and Rye Cereal Grains Using LC-QTOF-MS

摘要

1. The chemical tagging of the TG2 activated sites together with LC-QTOF and Ion trap MS has enabled the discovery of more than 20 peptides that can serve as markers for the presence of trace amounts of wheat, rye and barley in foods; these peptides are not native to grains considered gluten free such as corn or rice. 2. The use of multiple peptide markers for each grain type better ensures less false negatives in trace gluten detection. 3. RP, SEC and WCX give different selectivity for gluten peptide identification. 4. Since tagged peptide MW's are close (1000-3500Da), WCX seems to offer a wider retention window for elution with 2D chromatography. 5. The LC-QTOF offered several advantages in the biomarker peptide discovery: 1) molecular weights of potential marker peptides could be determined in 1-3 mmu from the fluorescence tagged peptides. 2) EICs using 10 mmu windows centered on the postulated peptide MW resulted in fewer peaks, simplifying the discovery of the peptide in the untagged gluten sample (compared to the numerous peaks observed in a LCMS run using a 1 mass unit window). 3) accurate mass and auto MS/MS aided in verifying amino acid composition, sequencing and reduced the number of possible hits in database searching.