Mining and characterization of novel peptides from soy protein hydrolysates that ameliorate insulin resistance based...

Inhibition of protein tyrosine phosphatase 1B (PTP1B) holds promise for ameliorating insulin resistance (IR). Through enzymatic bioconversion of soy protein-a major agro-industrial byproduct-we identified four PTP1B-inhibitory peptides (D-8-N, K-8-F, K-11-M, D-10-E) using cell hypoglycemic activity-guided purification and in silico screening. Molecular dynamics and docking suggested allosteric inhibition via hydrogen bonding, electrostatic interactions, and hydrophobic forces. Meanwhile, FTIR and AFM analysis suggested that there might be an interaction between PTP1B and peptide. Lineweaver-Burk plots demonstrated that all four peptides exhibited characteristics of non-competitive inhibitors. Based on molecular predictions and experimental validation, K-8-F exhibited the strongest inhibitory activity against PTP1B (IC₅₀ = 1.65 ± 0.81 μM), with pull-down experiments providing biological evidence. The western blotting indicated that K-8-F ameliorated IR via PTP1B/IRS1/AKT pathway modulation. This study proposes an integrative strategy to transform food-processing byproducts into therapeutic peptides, while providing some insights into structural determinants of PTP1B inhibition-contributing to bioactive peptide discovery and the sustainable valorization of plant proteins.