Molecular interactions and physiological effects of oyster-derived synthetic peptide-calcium complex: Insight in improving the bone growth and health

In this study, the oyster-derived synthetic peptide VAPEEHPV (V) was utilized to prepare the VCa complex with calcium ions . The results from frontier orbital analysis, molecular docking , and molecular dynamics simulations indicated that the primary binding sites were the carboxyl oxygen of Glu and the amide bond oxygen of Ala and Pro, while the VCa complex demonstrated stability in aqueous environments. Furthermore, various characterization techniques revealed that, in comparison to peptide V, VCa exhibited a decrease in UV absorption intensity and β-sheet content, an increase in particle size (from 720 to 1265 nm), enhanced thermal stability , and a rougher surface morphology. In a calcium deficiency mouse model, a medium dose of VCa improved the structure of the small intestinal villi , increased serum calcium levels (4.11 mmol/L) and phosphorus levels (2.01 mmol/L), and reduced alkaline phosphatase (AKP) levels (49.4 King Units/100 mL). Regarding bone quality, a high dose of VCa, superior to CaCO 3 , significantly increased bone calcium content (femur: 178.57 mg/g, tibia: 178.59 mg/g) and bone density (femur: 1.67 g/cm 3 , tibia: 1.82 g/cm 3 ). The deterioration of osteoclasts and tissue inflammation induced by calcium deficiency was markedly improved, and the thickness of the bone cortex increased to 713.91 μm. • V bound to calcium via carboxyl oxygen of Glu-4 and amido bond of Ala-2, Pro-3. • Steric hindrance could influence the donating oxygen in V with calcium. • VCa recovered calcium deficiency-induced bone damages and defects. • VCa reduced the inflammatory infiltration of cancellous bone and medullary cavities.