Screening and identification of DPP-IV inhibitory peptides from deer skin hydrolysates by an integrated approach of LC-MS/MS and in silico analysis

An integrated approach combining liquid chromatography/tandem mass spectrometry (LC-MS/MS) with in silico analysis was used to screen dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from deer skin hydrolysates. A total of 203, 244 and 60 peptides were identified from deer skin hydrolysates prepared with pepsin, pepsin + trypsin and pepsin + Alcalase, respectively, by LC-MS/MS. The percentages of peptides in the above mentioned hydrolysates containing a Pro residue at the penultimate position were 5.9, 20.9 and 20.0%, respectively. Five peptides with a Pro residue at the penultimate position were synthesized and assessed, and these five synthetic peptides possessed DPP-IV inhibitory activity with IC50 values from 83.3 to 1638.3 µΜ. One of the evaluated peptides contained an oxidized methionine. The effects of peptide modification and length on the DPP-IV inhibitory activity of the peptides were assessed. The results suggest that the integrated approach was efficient in identifying novel bioactive peptides from hydrolysates.