Asymmetrical flow field flow fractionation combined with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry used to screen allergen protein epitopes

: Asymmetrical flow field flow fractionation (AF4) combined with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was used to screen allergen protein epitopes. The selected allergen protein (tropomyosin, TM) was enzymatically digested into peptide segments and analyzed via UPLC-QTOF-MS to establish a protein-specific peptide database. The peptide segments were incubated with immunoglobulin E (IgE) for 30 min. During the incubation procedure, the specific peptide segments (with the antigen epitope) combine with IgE while the other peptide segments remain in solution. After incubation, the solution was injected into the AF4 device. The combined peptide segments flowed out of the outlet along with IgE, and the other peptide segments flowed into the waste liquid. The components of outlet were then collected, analyzed by UPLC-QTOF-MS, and the results matched with the spectra of the protein peptides. Eventually the specific peptide segments were identified to detect the antigen epitopes. This study extends the application of AF4 with a preliminary exploration of the detection of an allergen protein epitope, providing a novel research strategy for the screening of allergen epitopes.