Abstract: In this study, the physicochemical properties of two bitter peptides derived from yak cheese, RPKHPIK (RK7) and KVLPVPQ (KQ7) were calculated by using online bioinformatics tools such as ExPASy-ProtParam, Innovagen, and Pep-Draw. Molecular docking was used to elucidate the mechanism of the inhibitory effect of the two peptides on α-amylase and their α-amylase inhibitory activity was determined. The results showed that the molecular masses of RK7 and KQ7 were 875.07 and 779.98 Da, and their hydrophobicity were 42.86% and 71.42%, respectively. Molecular docking showed that His305, Glu233, Trp59 and Trp58 in α-amylase played an important role in binding to RK7 and KQ7. Furthermore, Asp197, Glu233 and Asp300 were the key amino acids for the activity of α-amylase. The half maximal inhibitory concentration (IC50) of RK7 and KQ7 against α-amylase were 0.45 and 0.86 mg/mL, respectively. The findings of this study provide new evidence for the study of α-amylase inhibitory peptides.

Key words: yak cheese; bitter peptide; α-amylase inhibitory activity; molecular docking; mechanism of action