Preparation of Calcium-Binding Phosvitin Phosphopeptide and Structural Characterization of Its Calcium Chelate

To prepare a calcium-binding peptide as calcium supplement, phosvitin phosphopeptide (PPP) was prepared from egg yolk and chelated with calcium ions. Phosvitin (PV) was treated at high temperature and high pressure, and then sequentially hydrolyzed with trypsin and alkaline protease. Based on hydrolysis degree and calcium binding efficiency of peptide, the hydrolysis conditions of alkaline protease were optimized. Phosvitin phosphopeptide-calcium chelate (PPP-Ca) was characterized by ultraviolet (UV) spectroscopy, infrared (IR) spectroscopy, circular dichroism (CD) spectroscopy, scanning electron microscopy (SEM) and zeta potential analysis. The results revealed that the optimal hydrolysis conditions were as follows: enzyme dosage 5%, hydrolysis time 90 min, pH 9.0 and 40 ℃. Under these conditions, the degree of hydrolysis was (25.45 ± 0.17)% and the calcium binding efficiency of peptide was (93.41 ± 1.10)%. The structural characterization showed that Ca bound to PPP mainly through interactions between carboxyl, amino and phosphate groups, and the structure of PPP-Ca was tightly ordered and had aggregation phenomenon.