Isolation and characterization of zinc-chelating peptides from wheat germ protein hydrolysates

• WGPH prepared by Alcalase FG 2.4L had strong metal chelating ability of 69.62 ± 0.96%.
• A novel zinc-chelating peptide (HNAPNPGLPYAA) was isolated and purified from WGPH.
• HNAPNPGLPYAA had a high zinc chelating capacity of 91.67 ± 0.81%.
• HNAPNPGLPYAA possessed higher zinc bioavailability than ZnSO4 in Caco-2 cells.

The enzymatic hydrolysis of defatted wheat germ protein was carried out by using Alcalase, Flavourzyme and papain. The hydrolysates prepared by Alcalase under optimal conditions for 200 min had the highest degree of hydrolysis (DH) of 15.61 ± 0.09% and metal chelating ability of 69.62 ± 0.96%. The zinc-chelating peptides were isolated and purified from Alcalase hydrolysates using immobilized metal ion affinity chromatography (IMAC-Zn2+) and macroporous adsorption resin DA 201-C. Two major zinc-chelating peptides identified by MALDI TOF/TOF were Asn-Ala-Pro-Leu-Pro-Pro-Pro-Leu-Lys-His (NAPLPPPLKH) and His-Asn-Ala-Pro-Asn-Pro-Gly-Leu-Pro-Try-Ala-Ala (HNAPNPGLPYAA). HNAPNPGLPYAA had a high zinc chelating capacity of 91.67 ± 0.81% and possessed higher zinc bioavailability than ZnSO4 in Caco-2 cells (P<0.05). The results of this study suggest that wheat germ zinc-chelating peptides might be useful in zinc fortification of foods for increasing mineral bioavailability.