Molecular mechanism of interaction between mannoprotein and proanthocyanidin

This study investigates the interaction between mannoproteins (MP) and proanthocyanidins (PA) to enhance the stability of mulberry juice and wine. MP addition significantly reduced UV-induced PA degradation, altered MP's apparent color, and improved antioxidant activity by approximately 22%. The zeta potential of MPs decreased from -3.97 ± 0.46 to -21.8 ± 0.53, while particle size increased from 174.77 ± 4.39 to 367.20 ± 2.05. Fluorescence spectroscopy and secondary structure analysis revealed PA-induced structural changes in MP, including a shift in the maximum absorption peak from 317 nm to 326 nm and a transition from antiparallel β-sheets to intramolecular β-sheets. Molecular docking identified key binding residues (ASP-245, THR-233, SER-235, LYS-247, ASN-256, TYR-293) with a binding affinity of -7.06 kcal/mol. These findings elucidate the binding mechanism of MP and PA, enhancing the stability and quality of mulberry-based products.