Structure, Stability, and Calcium Transport Mechanism of a Novel Duck Plasma Peptide-Calcium Chelate (LHDVK-Ca).

This study constructed a peptide-calcium chelate (LHDVK-Ca) using the duck plasma-derived pentapeptide LHDVK to investigate its binding mechanism, stability, and intestinal transport behavior. Spectroscopic analysis combined with isothermal titration calorimetry (ITC) revealed that LHDVK binds Ca2+ primarily through the carboxyl group of the aspartic acid residue with a single binding site and moderate affinity. Molecular simulations confirmed that Asp plays a dominant role in coordinating Ca2+. The chelate exhibited enhanced thermal stability and maintained high calcium retention under simulated gastrointestinal conditions. LHDVK-Ca markedly enhanced calcium absorption and translocation in Caco-2 cells by increasing TRPV6, Calbindin D9k, and PMCA1b expression, suggesting a TRPV6-dependent transcellular pathway. This study provides new evidence that short peptides derived from underutilized poultry byproducts can form stable calcium chelates with preferential binding sites and promote intestinal calcium transport through regulation of calcium-related pathways, offering potential for functional food applications.