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Hidden “Digestome”: Current Analytical Approaches Provide Incomplete Peptide Inventories of Food Digests
- De Cicco, Maristella, Mamone, Gianfranco, Di Stasio, Luigia, Ferranti, Pasquale, Addeo, Francesco, Picariello, Gianluca
- Journal of agricultural and food chemistry 2019 v.67 no.27 pp. 7775-7782
- algorithms, allergenicity, beta-lactoglobulin, bioinformatics, crosslinking, disulfides, high performance liquid chromatography, ions, lactalbumin, polypeptides, proteomics, tandem mass spectrometry, trichloroacetic acid, whey protein
- Analyzing an in vitro gastroduodenal digest of whey proteins by high-performance liquid chromatography (HPLC) coupled to high-resolution/high-sensitivity tandem mass spectrometry (MS/MS), we sought to evaluate if state-of-art peptidomics provide comprehensive peptide coverage of food “digestomes”. A multitude of small-sized peptides derived from both α-lactalbumin and β-lactoglobulin as well as disulfide cross-linked hetero-oligomers remained unassigned, even when the digests were compared before and after S–S reduction. The precipitation with 12% trichloroacetic acid demonstrated the occurrence of large-sized polypeptides that escaped the bioinformatic identification. The analysis of a HPLC–MS/MS run with different proteomic search engines generated dissimilar peptide subsets, thus emphasizing the demand of refined searching algorithms. Although the MS/MS fragmentation of monocharged ions with exclusion of non-peptide-interfering compounds enlarged the inventory of short peptides, the overall picture of the “digestome” was still incomplete. These findings raise relevant implications for the identification of possible food-derived bioactive peptides or allergenic determinants.