biostudies-literatureUnknown73(22)Xu QImmuno- and mass spectrometry (MS) test methods have been used to ensure "gluten-free" food products contain less than 20 ppm of gluten. However, comparison of test method performance is difficult due to differences in reporting units. A set of wheat flour fractions was prepared and characterized regarding immunoglobulin E (IgE)-reactivity and protein profile, which were then used to screen a panel of gluten peptides to identify reporters suitable for use in an MS test method for gluten determination. Four peptide markers were selected and synthesized as heavy isotopically labeled versions for further evaluation. Two were derived from α-gliadin (RPQQPYPQPQPQY and QPFPQPQLPY [spanning a celiac toxic motif]), one each from γ-gliadin (GIIQPQQPAQL [spanning a celiac toxic motif and IgE epitopeJournal of agricultural and food chemistry14099-14111https://www.ebi.ac.uk/biostudies/studies/S-EPMC12147133biostudies-literatureFrom Peptide to Protein: Development of Conversion Factors for the Quantification of Gluten Using Targeted Mass Spectrometry.PMC12147133Simpson AMills ENCRogers ANitride CDaly MGethings LAXu QShewry PRTranquet OBartra-Tomas JfalseFrom Peptide to Protein: Development of Conversion Factors for the Quantification of Gluten Using Targeted Mass Spectrometry.Immuno- and mass spectrometry (MS) test methods have been used to ensure "gluten-free" food products contain less than 20 ppm of gluten. However, comparison of test method performance is difficult due to differences in reporting units. A set of wheat flour fractions was prepared and characterized regarding immunoglobulin E (IgE)-reactivity and protein profile, which were then used to screen a panel of gluten peptides to identify reporters suitable for use in an MS test method for gluten determination. Four peptide markers were selected and synthesized as heavy isotopically labeled versions for further evaluation. Two were derived from α-gliadin (RPQQPYPQPQPQY and QPFPQPQLPY [spanning a celiac toxic motif]), one each from γ-gliadin (GIIQPQQPAQL [spanning a celiac toxic motif and IgE epitope2025-01-01T00:00:00Z2025 Jun2026-06-02T20:30:57.676Z2026-04-20T03:10:14.184ZS-EPMC121471334040170210.1021/acs.jafc.4c12344