Structural Characteristics and Immunoregulatory Effects of Colla Corii Asini Peptides with Iron‐Chelating Capacity
Qing‐Tao Zhan, Zi‐Wei Zhao, Jian‐Hang Cai, Xue‐Mei Ge, Shuang‐Di Chen, Xue Tang, Xue‐Ying Ma, Liu‐Ping Fan, Issoufou Amadou, Xiang‐Rong ChengABSTRACT
Iron homeostasis is closely related to immune function, yet the structural basis of food‐derived peptides that modulate this iron‐immune crosstalk remains unclear. This study investigated the structure‐function relationship of Colla Corii Asini (Ejiao) peptides fractionated by immobilized metal affinity chromatography (IMAC‐Fe 2+ ). The strongly iron‐chelating fraction (F2) exhibited a capacity of 34.57 ± 0.59 µg Fe 2+ /mg peptide, which was 10.7‐fold higher than the weakly chelating fraction (F1). Sequence analysis revealed that F2 was characterized by a high abundance of acidic amino acids (42.87 ± 1.76%) and a recurrent E‐Xn‐P motif, which may represent an important structural feature associated with Fe 2+ coordination. In cyclophosphamide‐induced immunosuppressed mice, F2 significantly outperformed the weak‐chelating fraction (F1) in restoring immune function, including increasing splenic CD3 + T cells and mucosal IgA levels. Mechanistically, F2 restored systemic iron homeostasis by normalizing hepatic transferrin and hepcidin levels. These findings characterize F2 as a structurally distinct peptide fraction with potential functional‐food relevance for regulating the iron‐immune axis.