Sequential alcalase and flavourzyme treatment for preparation of α-amylase, α-glucosidase, and dipeptidyl peptidase (DPP)-IV inhibitory peptides from oat protein

• Published in: Journal of functional foods Vol. 87; p. 104829
• Main Authors: Ramírez Fuentes, Lourdes, Richard, Caroline, Chen, Lingyun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2021; Elsevier
• Subjects: Antidiabetic peptides; DPP-IV inhibition; Oat protein; Peptide sequencing; Type 2 diabetes; α-amylase inhibition; Antidiabetic peptides; DPP-IV inhibition; Type 2 diabetes; Peptide sequencing; α-amylase inhibition; Oat protein
• ISSN: 1756-4646; 2214-9414
• DOI: 10.1016/j.jff.2021.104829

[Display omitted] •Oat protein treated by alcalase and flavourzyme is a good source of antidiabetic peptides.•Oat peptides can inhibit three of the main glucose regulating enzymes: α-amylase, α-glucosidase, and DPP-IV.•Ultrafiltration and RP-HPLC fractionation enhanced the antidiabetic effect of oat peptides.•LC-MS/MS analysis displayed in total 27 de novo sequences from the most effective fractions. The current study reported oat protein as a precursor for α-amylase, α-glucosidase, and dipeptidyl peptidase (DPP)-IV inhibitory peptides and studied the antidiabetic activities related to their structures. Enzyme inhibition assays in vitro, using oat protein treated by alcalase and flavourzyme fractionated into different molecular weights and hydrophobicity, indicated that the relatively hydrophobic fraction of 1–5 kDa inhibited enzymes related to glucose digestion, absorption, and metabolism activities. The α-amylase and DPP-IV were inhibited 57 and 78%, respectively, even at low peptide concentrations. LC-MS/MS analysis of the most effective fractions disclosed two eight amino acid sequences, identified from 12S oat globulin (GDVVALPA and DVVALPAG), and other sequences rich in amino acids like proline, leucine, valine, phenylalanine, and glutamine. The results suggest that proline and hydrophobic amino acids may favor hydrophobic interactions and hydrogen bonding with the target enzymes, especially the Leu-Pro sequence found in potent DPP-IV inhibitors.