CPe-III-S Metabolism in Vitro and in Vivo and Molecular Simulation of Its Metabolites Using a p53-R273H Mutant.

It was previously found that CPe-III-S, synthesized according to the chickpea peptide CPe-III (RQSHFANAQP), exhibited an antiproliferative effect. The aim of this study was to investigate the antiproliferative mechanism of CPe-III-S. CPe-III-S was treated by pepsin and trypsin in a simulated gastrointestinal digestion environment as well as in an animal experiment. With HPLC-ESI-MS analysis, three peptide fragments of Ser-His, His-Phe, and Ala-Asn-Ala-Gln were identified. Ser-His was the only common product from both in vitro and in vivo environments. The specific bindings between three peptides and p53-R273H were performed by molecular docking, and the molecular dynamic simulation between Ser-His and p53-R273H revealed the stability of the binding complex. The binding free energy of the complex was -12.56 ± 1.03 kcal/mol with a reliable hydrogen bond between the ligand and Thr284 of p53. Ser-His may restore mutant p53-R273H activity or inhibit its binding with a downstream signal. This metabolite is a potential anticancer factor for suppressing cell proliferation.