钙结合卵黄高磷蛋白磷酸肽的制备及其肽钙螯合物的结构表征

以鸡蛋蛋黄为原料制备卵黄高磷蛋白磷酸肽（phosvitin phosphopeptide,PPP），并与钙离子螯合制备肽钙补充剂。通过高温高压处理卵黄高磷蛋白，先用胰蛋白酶酶解，以水解度和肽钙结合率为指标，进一步优化碱性蛋白酶的酶解条件以制备PPP。PPP与钙螯合获得螯合物PPP-Ca，通过紫外光谱、红外光谱分析、圆二色谱分析、扫描电镜和Zeta电位分析表征PPP-Ca的结构特性。结果表明最佳酶解条件为加酶量5%、酶解90 min、pH 9.0、温度40℃，在此最优条件下水解度为（25.45±0.17）%，肽钙结合率为（93.41±1.10）%。结构表征发现PPP-Ca主要通过羧基、氨基和磷酸基团相互作用结合，PPP和钙离子结合后其结构变得紧密有序，且有聚集现象。

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.