Binding of divalent metal ions to 1-25 β-caseinophosphopeptide: An isothermal titration calorimetry study

► We determine the binding parameters for Ca2+, Mg2+, Zn2+, and Cu2+ on β-CN(1-25)4P. ► We use isothermal titration calorimetry performed at pH 8 (pH of ileum). ► Zn2+ displays the highest affinity and Cu2+ does not bind to the peptide at pH 8. ► One mole of peptide chelates 2 mol of Ca2+, Mg2+, and Zn2+ at pH 8.