Multimodal calcium coordination and transport mechanisms of cod bone-derived novel peptides DYGGEY and GESGEAGDR

This study characterized two novel cod bone-derived peptides, DYGGEY and GESGEAGDR, revealing distinct Ca-binding architectures and transport routes. DYGGEY displayed a higher Ca-binding capacity (68.42 ± 3.15 mg/g) than GESGEAGDR (54.73 ± 2.96 mg/g), accompanied by secondary structural rearrangements after Ca chelation. Spectroscopy and NMR demonstrated that DYGGEY formed compact 1:1, 1:2, and 2:2 peptide-Ca complexes mainly via Asp/Glu/Tyr carboxyl coordination, whereas GESGEAGDR adopted more flexible 1:1 and 1:2 complexes involving Glu/Asp and protonated Arg. These structural differences led to divergent transport behaviors. DYGGEY (1.0 mg/mL) increased Ca transport from 26.95 ± 1.20 to 37.05 ± 5.63 μg/well and bioavailability from 33.45 ± 3.38% to 49.17 ± 6.43%, primarily through TRPV6 and L-type channel activation. In contrast, GESGEAGDR elicited modest transport enhancement but markedly promoted intracellular Ca retention via clathrin-dependent endocytosis. Proteomic analysis further revealed that DYGGEY and GESGEAGDR differentially modulated cellular Ca homeostasis.