Isolation and identification of a whey protein-sourced calcium-binding tripeptide Tyr-Asp-Thr

A tripeptide peptide with strong calcium-binding capacity was isolated and purified from whey protein hydrolysates using diethylaminoethyl cellulose anion-exchange chromatography, Sephadex G-25 gel filtration, semi-preparative reversed-phase (RP) high-performance liquid chromatography (HPLC) and analytical HPLC. It was identified using liquid chromatography-electrospray ionisation mass spectrometry and shown to have a molecular mass of 396.98 Da with the confirmed amino acid sequence Tyr-Asp-Thr. The calcium-binding capacity of Tyr-Asp-Thr reached 79.5 μg mg−1, an increase of 134% compared with the unpurified hydrolysate complex. The characteristics of the Tyr-Asp-Thr-Ca chelate were investigated, indicating that the major binding sites included oxygen atom of the carbonyl group and nitrogen of amino group or imino group; structural modifications of the peptide arose with the addition of calcium ion. The findings suggest the potential of peptide-calcium chelates as dietary supplements.