A complete workflow for discovering small bioactive peptides in foods by LC-MS/MS: A case study on almonds - ScienceDirect

Fig 1. Q-TOF tandem MS spectra of nonderivatized and dimethyl-labeled peptide standards (A. Val-Tyr; B. Val-Tyr-Val). The spectrum of dimethyl-labeled Val-Tyr-Val was zoomed in; the peak intensity of the a1 ion of dimethyl-labeled Val-Tyr-Val was 9.0 × 105. Fig 2. Q-TOF tandem MS spectra of nonderivatized and dimethyl-labeled peptides identified from the ENZ protein-rich extract from almond flour (A. Gly-Val-Lys-Tyr; B. Lxx-Lxx-Tyr). The spectrum of dimethyl-labeled Lxx-Lxx-Tyr was zoomed in; the peak intensity of the a1 ion of dimethyl-labeled Lxx-Lxx-Tyr was 1.4 × 104. Fig 3. Length distribution of peptides identified in the protein-rich extracts from almond flour. Peptides composed of 2–4 amino acids were identified via de novo sequencing from both nonderivatized and dimethyl-labeled samples; peptides with ≥ 5 amino acids were identified through database search from a nonderivatized sample. Fig 4. Venn diagrams of numbers of small peptide sequences identified in the nonderivatized a

Fig 1. Q-TOF tandem MS spectra of nonderivatized and dimethyl-labeled peptide standards (A. Val-Tyr; B. Val-Tyr-Val). The spectrum of dimethyl-labeled Val-Tyr-Val was zoomed in; the peak intensity of the a1 ion of dimethyl-labeled Val-Tyr-Val was 9.0 × 105. Fig 2. Q-TOF tandem MS spectra of nonderivatized and dimethyl-labeled peptides identified from the ENZ protein-rich extract from almond flour (A. Gly-Val-Lys-Tyr; B. Lxx-Lxx-Tyr). The spectrum of dimethyl-labeled Lxx-Lxx-Tyr was zoomed in; the peak intensity of the a1 ion of dimethyl-labeled Lxx-Lxx-Tyr was 1.4 × 104. Fig 3. Length distribu