Novel Casein-Derived Peptide-Zinc Chelate: Zinc Chelation and Transepithelial Transport Characteristics

Casein-derived peptides are recognized as promising candidates for improving zinc bioavailability through the form of a peptide-zinc chelate. In the present work, a novel 11-residue peptide TEDELQDKIHP identified from casein hydrolysate in our previous study was synthesized to investigate the zinc chelation characteristics. Meanwhile, the digestion stability and transepithelial transport of TEDELQDKIHP-Zn were also investigated. The obtained results indicated that the carboxyl groups (from Asp and Glu), amino groups (from Lys and His), pyrrole nitrogen group of Pro, and imidazole nitrogen group of His were responsible for zinc chelation. The complexation with zinc resulted in a more ordered structure of TEDELQDKIHP-Zn. In terms of digestion stability, the chelate of TEDELQDKIHP-Zn could remain stable to a large extent after gastric (78.54 ± 0.14%) and intestinal digestion (70.18 ± 0.17%). Moreover, TEDELQDKIHP-Zn was proven to be a well-absorbed biological particle with a P_app value higher than 1 × 10^-6 cm/s, and it could be transported across the intestine epithelium through transcytosis. TEDELQDKIHP-Zn exhibited more bioavailable effects on zinc absorption and ALP activity than inorganic zinc sulfate.