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Open Access Issue
Isolation, Purification and Stability of Antimicrobial Peptides from Walnut Glutenin
Food Science 2024, 45(7): 69-77
Published: 15 April 2024
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Objective

To prepare antimicrobial peptides (AMPs) as a new alternative to antibiotics from walnut glutenin.

Methods

AMPs were prepared by solid-state fermentation using Bacillus subtilis synchronized with alkaline protease treatment, separated, purified, and screened by successive ultrafiltration, gel filtration chromatography, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and molecular docking. The stability of AMPs was studied by using Escherichia coli and Staphylococcus aureus as indicator strains.

Results

fractions WGP-IIIA and WGP-IIIC, obtained after gel filtration chromatography, had strong antibacterial activity. By LC-MS/MS combined with virtual screening, 6 peptides were identified from the 2 fractions, and 3 peptides were obtained by molecular docking, namely LAEAYNIPDTIARRL from WGP-IIIA and SHSVIYVIR and APQLLYIVK from WGP-IIIC. The results of molecular docking showed that the antibacterial activity of WGP-IIIC was stronger. The AMPs were stable to high temperature, ultraviolet light, varying pH and different proteases.

Conclusion

Walnut AMPs have application value in the field of food preservation.

Open Access Basic Research Issue
Isolation, Purification, Identification and Binding Site Analysis of Walnut Glutelin Peptides and Their Zinc Chelates
Food Science 2024, 45(22): 8-16
Published: 25 November 2024
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In order to improve the added value of walnut, walnut glutelin peptides (WGPs), which were prepared from walnut meal, were chelated with zinc ions. The zinc chelating characteristics of WGPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) spectroscopy. The peptides were screened for zinc binding capacity by ultrafiltration, gel column chromatography and liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the specific binding sites and binding capacity of the peptides were explored by molecular docking. The results showed that WGPs could chelate with zinc ions, leading to significant alterations in the surface microstructure and crystallinity of the peptides. After ultrafiltration and gel column chromatography, fraction F41, which had the highest chelating capacity of (117.43 ± 1.99) mg/g, was obtained. By LC-MS/MS combined with virtual screening, five potential bioactive peptides without toxicity or allergenic potential were identified. Molecular docking was used to simulate and analyze the binding process. It was found that pentapeptide Phe-Asp-Ala-Asp-Phe (FDADF) could form a structurally stable complex with zinc ions through coordination bonds, hydrogen bonds and hydrophobic interactions. Among the five peptides, the pentapeptide exhibited the lowest binding energy (-7.27 kcal/mol), and the main binding site was the carboxyl oxygen atom (Asp4: O-Zn) of the aspartic acid (Asp) side chain. This study provides a theoretical basis for the development and application of zinc-chelating peptides.

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