A　specific　peptide　displaying　calcium-binding　capacity　was　purified　from　whey　protein　hydrolysate.　The　isolation　procedures　included　DEAE　anion-exchange　chromatography,　Sephadex　G-25　gel　filtration,　and　reversed-phase　high-performance　liquid　chromatography　(RP-HPLC).　The　amino　acid　sequence　of　the　peptide　was　determined　to　be　Phe-Asp　(FD),　using　liquid　chromatography-electrospray　ionization-tandem　mass　spectrometry　(LC-ESI-MS/MS).　The　calcium　binding　capacity　of　FD　reached　73.34　mu　g/mg,　and　the　amount　increased　by　116%　when　compared　to　the　whey　protein　hydrolysate　complex.　The　structural　properties　of　the　purified　peptide　were　identified　using　fluorescence　spectra,　Fourier　transform　infrared　spectroscopy　(FTIR),　and　H-1　nuclear　magnetic　resonance　(NMR)　spectroscopy,　respectively.　The　results　indicated　that　the　amido　and　carboxy　groups　of　the　purified　peptide　were　transformed　during　chelation.　The　oxygen　atoms　of　the　carboxy　group　and　the　nitrogen　atoms　of　the　amido　group　could　chelate　calcium　to　form　coordinate　bonds　by　donating　electron　pairs.　Furthermore,　FD-Ca　chelate　was　found　to　be　more　stable　and　absorbable　than　CaCl2　under　both　acidic　and　basic　conditions.　Our　findings　suggest　that　the　purified　dipeptide　Phe-Asp　has　the　potential　to　be　used　as　a　calcium-binding　ingredient　in　dietary　supplements.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.