Characteristics And Structure Identification Of Sunflower Seed Septides And Peanut Peptides During Calcium Binding

In this study, the sunflower seed peptide and peanut peptide were prepared by enzymatic hydrolysis of sunflower seed protein and peanut protein, and explore its calcium binding properties. Furthermore, the calcium-binding peptides of the sunflower seed peptide and peanut peptide were isolated and purified, and identified the primary structure.First, this paper studies the calcium binding capacity of the sunflower seed peptide and peanut peptide. Results showed that,12 kinds hydrolysates obtained using Protease M possess calcium binding capacity in pH 7.4 conditions, but the calcium binding capacity was significantly different. The amount of calcium bound of peanut protein hydrolysates was the highest that the degree of hydrolysis was 11.8%, up to 110.8mg/g. The amount of calcium bound of sunflower seed protein hydrolysates was 83.5mg/g that the degree of hydrolysis was 10.2%. The calcium binding properties of sunflower seed peptide and peanut peptide were analyzed with FTIR. The results show that the most likely sites for calcium binding of sunflower seed peptide and peanut peptide are the amino group. The stability of soluble sunflower seed and peanut peptide-calcium complex treated by pepsin and trypsin was also studied. Results showed that calcium combining amount of sunflower seed and peanut peptide-calcium complex could be maintained at least 62.40% and 74.05% after digested by pepsin and trypsin, which demonstrated that sunflower seed and peanut peptide-calcium complex possessed some stability to the digestion.The calcium-binding peptides of sunflower seed and peanut were identified with MS/MS. The characteristics of amino sequences of sunflower seed peptides were follow: high content of lysine (K), and containing lysine (K), arginine (R), histidine (H) in sequence:KK、RK、RR、HH. The characteristics of amino sequences of peanut peptides were follow:high content of arginine (R), and contains arginine (R) and histidine (H) in sequence:RRR、HR、RR. At the same time, the relationship of amino acid composition and calcium binding capacity was also studied. The calcium binding capacity of sunflower seed peptide and peanut peptide were shown to be related with the content of arginine, lysine, histidine.