The chelation mechanism, stability and calcium absorption activity of Ruditapes philippinarum peptide‑calcium chelate

DSEDLPL was the peptide with better Ca 2+ -binding activity via molecular docking. • RPP-Ca had good stability (heat/digestive resistance; Ca stability in neutral/weakly alkaline). • RPP-Ca had high safety. • RPP-Ca had good bioavailability compared with calcium ions. This study optimized the preparation of peptide‑calcium chelates from Ruditapes philippinarum protein (RPP). Under optimal conditions, RPP's calcium-binding capacity reached 95.79 ± 2.09 mg/g. Structural characterization (FTIR, UV, SEM) and molecular docking revealed that chelation occurred via coordination bonds, hydrophobic interactions, and hydrogen bonds (binding energy: −5.74 kcal/mol, primarily involving carboxyl oxygen atoms in a bidentate pattern. RPP-Ca demonstrated high stability, maintaining an 80%–85% calcium retention rate at pH 6.0–10.0. Furthermore, calcium transport assays showed that RPP-Ca’s transport capacity was 42.20 ± 1.54% higher than that of inorganic CaCl 2 . These findings indicate that RPP-Ca is a stable, high-affinity chelate with superior bioavailability, making it a promising candidate for functional calcium supplementation.