Isolation and characterization of zinc-binding peptides from mung bean protein hydrolysates

The aim of this study was to isolate, purify, and characterize a novel peptide with zinc-binding ability from mung bean protein hydrolysates obtained by alcalase. The peptide purification process was performed using ultrafiltration, TSK-GEL size-exclusion chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC). The molecular weight of the isolated peptide was determined by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) and found to be 1192.56 Da with amino acid sequence SSEDQPFNLR. The identified peptide showed zinc-binding capacity of 80.82 mg/g, which is 55.09% higher than that of the original mung bean protein hydrolyzate. Moreover, UV-vis and FTIR spectra indicated that the zinc-binding sites on the peptide were nitrogen atoms of amide, terminal amino group, and oxygen atoms on the carboxyl group. Moreover, zinc-releasing experiments showed that the peptide-zinc chelate is highly soluble under both acidic and alkaline conditions. Furthermore, the identified peptide significantly promoted the transportation and absorption of zinc ions in Caco-2 cell model. These findings indicate a potential for production of zinc-binding peptide from mung bean protein for the utilization as ingredient in functional foods.