A pivotal peptide (Val-Ser-Glu-Glu) from duck egg white promotes calcium uptake and structure-activity relationship study

The effects of desalted duck egg white peptides (DPs) and Val-Ser-Glu-Glu (VSEE) on calcium absorption were investigated in calcium-deficient diets rat model. Six-week oral administration results indicated DPs + CaCO3 and VSEE + CaCO3 were significantly higher than CaCO3 group in calcium absorption, serum osteocalcin, bone calcium content and max load, but lower in serum bone alkaline phosphatase level (P < 0.05). Additionally, in the 0.5% calcium diets groups, the rats fed with DPs showed notably increases in calcium absorption, length of tibias and bone max load than those without DPs. The structure-activity relationship results demonstrated the importance of amino acid units like Glu-Glu and Ser-Ser. Homology modeling and molecular docking results provided two possible active sites of TRPV6 in the promotion of calcium uptake by DPs. The present study expands the understanding of the mechanism of calcium uptake in vivo by DPs, as well as highlights the structure-activity relationship and the potential active sites of TRPV6.