Enthalpy-entropy compensation in calcium binding to acid-base forms of glycine tyrosine dipeptides from hydrolysis of α-lactalbumin

[Display omitted] •GlyTyr binds calcium stronger for the pH condition of the intestine than TyrGly.•Calcium binding to acid/base forms of GlyTyr and TyrGly dipeptides is at neutral pH strongly exothermic.•Density Functional Theory suggests calcium binding to occur at carboxylates and amides.•Enthalpy–entropy compensation controls calcium binding to GlyTyr and TyrGly acid/base forms.•Calcium binding to GlyTyr and TyrGly decreases radical scavenging and antioxidative activity. Calcium binding to peptides formed by hydrolysis of whey proteins during digestion is important for calcium uptake in the intestines and affects the antioxidant function of the peptides. For the two dipeptides, Gly-Tyr and Tyr-Gly, potential hydrolysis products of α-lactalbumin, calcium binding to the three forms of each dipeptide in acid-base equilibrium at intestinal pH was determined electrochemically and compared to binding to tyrosine for aqueous 0.16 M NaCl for 5