Figure 1.

Schematic overview of the workflow used for confirmation of the identified nonhuman peptide sequences. After LC-MS/MS analysis, experimental MSMS spectra that matched theoretical nonhuman peptide sequences were selected when there was no close peptide sequence match (PSM) with a human peptide sequence. Spectra with a PSM score < 80 or a full match with the human proteome were removed. The final remaining spectra were confirmed with retention time and MSMS spectra of bovine milk, pure proteins, or synthetically acquired peptides.