A novel zinc‐chelating peptide identified from rapeseed (Brassica napus) protein hydrolysate: insights into its zinc‐binding sites by density functional theory

Abstract

SummaryThe binding sites between zinc chelating peptide (ZCP) and zinc have not been clearly understood at the quantum chemistry level. Ala‐Ser‐His (ASH), a new ZCP located in the cruciferin precursor, was identified from in vitro digestion hydrolysate of rapeseed (Brassica napus) protein. Also, ASH exerted the concentration value of 114.09 ± 0.98 mM showing 50% zinc chelating activity. The prepared ASH–Zn (ZCP‐zinc chelate), displayed varying characteristics from ASH on surface microstructures, X‐ray photon energies, and infrared spectrum. The geometric structure of ASH–Zn with minimum free energy was obtained using density functional theory, producing a bridge bond of O21–Zn41–O32 between Ser and His residues. Based on the basic set of 6–311++G (d, p), O21–Zn 41 and O32–Zn41, respectively, had bond lengths of 1.96503 Å and 1.94515 Å, while O21–Zn41–O32 displayed a bond angle of 136.41069°. These findings further promote research on rapeseed proteins providing new possibilities for studying peptide‐metal chelates.