Identification and Molecular Binding Mechanism of Novel α-Glucosidase Inhibitory Peptides from Hot-Pressed Peanut Meal Protein Hydrolysates

Abstract

Hot-pressed peanut meal protein hydrolysates are rich in Arg residue, but there is a lack of research on their α-glucosidase inhibitory activity. In this study, different proteases were used to produce hot-pressed peanut meal protein hydrolysates (PMHs) to evaluate the α-glucosidase inhibitory activity. All PMHs showed good α-glucosidase inhibitory activity with the best inhibition effect coming from the dual enzyme system of Alcalase and Neutrase with an IC50 of 5.63 ± 0.19 mg/mL. The fractions with the highest inhibition effect were separated and purified using ultrafiltration and cation exchange chromatography. Four novel α-glucosidase inhibitory peptides (FYNPAAGR, PGVLPVAS, FFVPPSQQ, and FSYNPQAG) were identified by nano-HPLC-MS/MS and molecular docking. Molecular docking showed that peptides could occupy the active pocket of α-glucosidase through hydrogen bonding, hydrophobic interaction, salt bridges, and π-stacking, thus preventing the formation of complexes between α-glucosidase and the substrate. In addition, the α-glucosidase inhibitory activity of PMHs was stable against hot, pH treatment and in vitro gastrointestinal digestion. The study demonstrated that PMHs might be used as a natural anti-diabetic material with the potential to inhibit α-glucosidase.

Development and Identification of Novel α-Glucosidase Inhibitory Peptides from Mulberry Leaves

“…sites [36,46]. In addition, some studies have proposed that peptides containing proline are more resistant to gastrointestinal digestion, which is consistent with the findings of AAGRLPGY and RWPFFAFM [47,48].…”

“…It seems that these three selected peptides are easily broken during the digestion process. Intestinal digestion may increase the activity of bioactive peptides by exposing more enzyme-binding sites [36,46]. In addition, some studies have proposed that peptides containing proline are more resistant to gastrointestinal digestion, which is consistent with the findings of AAGRLPGY and RWPFFAFM [47,48].…”

“…The opposite result appeared in this study; namely, the binding energy of RWPFFAFM (methionine at the C-terminal) was lower than that of VVRDFHNA (alanine at the C-terminal). This may be due to another factor affecting the inhibitory activity or the content of hydrophobic amino acids in the peptide [36]. More hydrophobic amino acids are present in RWPFFAFM (87.5%) than in VVRDFHNA (50%).…”

“…All three peptides exhibited similar binding to acarbose in the active pocket of the enzyme. The hydrophobic interaction, salt bridge, and hydrogen bond maintained the stability of the peptide-α-glucosidase (PDB ID: 5ZCE) complex [36]. Among them, hydrogen bonds played a primary role in the inhibition of bioactive peptides, and the number of hydrogen bonds was essential [27].…”

Alpha-Glucosidase Inhibitory Peptides: Sources, Preparations, Identifications, and Action Mechanisms

“…Molecular docking indicates that peptides can occupy the active pocket of α-glucosidase through hydrogen bonding, hydrophobic interaction, salt bridges, and π stacking, thus preventing α-glucosidase from forming a complex with substrates. Among these four peptides, PGVLPVAS had the lowest binding energy to α-glucoside, followed by FYNPAAGR, FFVPPSQQ, and FSYNPQAG [64]. Therefore, lower binding energy of peptides than that of acarbose could be used as another screening criterion.…”