Effect of calcium-binding peptide from Pacific cod (Gadus macrocephalus) bone on calcium bioavailability in rats

•Calcium binds to bone collagen peptide by interacting with amino and carboxyl.•Gly, Glu, Arg and Lys in this peptide were related to its ability to bind calcium.•Calcium-binding bone collagen peptide can increase the calcium absorption.•Calcium-binding bone collagen peptide enhanced calcium incorporation into bones.

Bone collagen peptide with high affinity to Ca was extracted from Pacific cod (Gadus macrocephalus) bone. FTIR spectra of calcium-binding bone collagen peptide showed that band at 3381 cm−1 shifted to 3361 cm−1, 1455 cm−1 moved to 1411 cm−1, and amide II became deeper valley, compared with that of bone collagen peptide. This peptide was sequenced by Q-TOF-MS and sequences of Gly-Pro-Glu-Gly, Gly-Glu-Lys, Gly-Pro-Leu-Gly and Gly-Leu-Pro-Gly appeared repeatedly in some peptides. From SEM, after chelated with calcium, the loose and porous structure turned into granular structure. From the animal experiment, Ca apparent absorption rate, Ca retention rate and femur Ca content of calcium-binding bone collagen peptide group were significantly higher than those of model and CaCO3 groups (P < 0.05), while serum ALP was significantly lower than model group (P < 0.05) and similar to control group. The results suggested that calcium-binding bone collagen peptide could improve bioavailability of Ca and thus prevented Ca deficiency.