Screening and identification of five peptides from pinto bean with inhibitory activities against α-amylase using phage display technique

• 5 novel anti α-amylase peptides were screened from Pinto bean.
• SyP9 exhibited the highest α-amylase inhibition activity with IC50 of 1.97 mg ml−1.
• His, Pro and Met residues in PBBP were proposed to be critical for the binding.
• Binding sites of amylase were predicted to be Tyr54, Leu194, Met195, Asp229, Ala230, His233, Asp326.
• The phage display technique had enhanced the bioactive peptide discovery process.

The objective of this study was to screen and identify α-amylase inhibitor peptides from Pinto bean. Five Pinto bean bioactive peptides were successfully identified: PPHMLP (P1), PLPWGAGF (P3), PPHMGGP (P6), PLPLHMLP (P7) and LSSLEMGSLGALFVCM (P9). Based on ELISA results, their promising optical density values were 1.27; 3.71, 1.67, 3.20 and 1.03, respectively, which indicated the binding interaction between the peptide and α-amylase occurred. The highest inhibitory activity (66.72%) of the chemically synthesized peptide was shown in SyP9 followed by SyP1 (48.86%), SyP3 (31.17%), SyP7 (27.88%) and SyP6 (23.96%). The IC50 values were 1.97, 8.96, 14.63, 18.45 and 20.56 mg ml−1, respectively. Structure activity relationship study revealed that α-amylase was inhibited due to its residues of Ala230, Asp229, Asp326, Tyr54, Met195, Leu194 and His233 were bound. On the other hand, the residues of PBBP (i.e. histidine, proline and methionine) were found to have the highest potency in the binding interaction.