Purification, Identification, Chelation Mechanism, and Calcium Absorption Activity of a Novel Calcium-Binding Peptide from Peanut (Arachis hypogaea) Protein Hydrolysate

A novel calcium-binding peptide was purified from peanutproteinhydrolysate using gel filtration chromatography and identified usingHPLC-MS/MS. Its amino acid sequence was determined as Phe-Pro-Pro-Asp-Val-Ala(FPPDVA, named as FA6) with the calcium-binding capacity of 15.67 & PLUSMN; 0.39 mg/g. Then, the calcium chelating characteristics of FPPDVAwere investigated using ultraviolet-visible absorption spectroscopy,fluorescence spectroscopy, Fourier transform infrared spectroscopy,particle size, and zeta potential. The results showed that FPPDVAinteracted with calcium ions, the chelation of calcium ions inducedFPPDVA to fold and form a denser structure, the calcium-binding sitesmay mainly involve oxygen atoms from the carboxyl residues of Aspand Ala, and Phe possessed contact energy and carbonyl residues ofVal. Microstructure analysis showed that FPPDVA-calcium chelate exhibiteda regularly ordered and tightly aggregated sheets or block structures.Additionally, FPPDVA-calcium chelate had good gastrointestinal digestivestability and thermal stability. The results of everted rat intestinalsac and Caco-2 cell monolayer experiments showed that FPPDVA-calciumchelate could promote calcium absorption and transport through theCav1.3 and TRPV6 calcium channels. These data suggest that FPPDVA-calciumchelate possesses the potential to be developed and applied as calciumsupplement.