Design and expression of recombinant Xuanwei ham antioxidant peptide in Escherichia coli BL21

Abstract

Xuanwei Ham Peptide (XHP) is a bioactive compound isolated and extracted from Xuanwei ham. It enhances the oxidative defense system by down-regulating CYP2E1 expression, reducing ROS production, and by activating the Nrf2/HO-1 pathway. In order to solve the problems of low yield, high cost and time-consuming separation process of active peptides from ham. In this study, we designed three peptide sequences derived from Xuanwei ham and expressed them recombinantly. The results showed that the peptides using flexible linker peptide ((GGGGS)2), rigid linker peptide ((EAAAK)2) linkage as well as the head-to-tail tandem linkage were successfully expressed in the E. coli expression system. Peptide monomers were released from the fusion proteins by formic acid cleavage and purified sequentially by Ni-IDA affinity chromatography, membrane filtration and RP-HPLC. The molecular weight of XHP was confirmed to be 717.35 by ESI-MS analysis. The results of the antioxidant activity of XHP showed that the hydroxyl radical scavenging rates of the three recombinant peptides were as high as 79.46%, 87.42%, and 53.60%, respectively. The hydroxyl radical activity of formic acid-cleaved XHP was reduced to 35.31%, but it showed good stability in heat, pH, metal ions and gastrointestinal digestion (GID). The molecular docking results showed that the docking of XHP to Keap1 protein was evaluated by five Molecular dynamics simulation with a maximum binding energy of -8.5 kcal/mol. This study provides references and ideas for the expression of active peptides, which can be widely used in the future can be used in the field of nutraceuticals, functional foods and pharmaceuticals.