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

Abstract

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.