In silico screening of a new calcium-binding nonapeptide from Hericium erinaceus and characterization of its calcium chelate

• Docking was used to screen Ca-binding peptides (CBP) from Hericium erinaceus (HE) • Calcium sensing receptor (CaSR) and Ca 2+ were used as targets in the screening • COO-, N-H, C-N and C=O groups were involved in the formation of WYEEGTDKA-Ca • WYEEGTDKA-Ca was tolerant to high temperature and simulated digestion in vitro • WYEEGTDKA-Ca exhibited promoting effects on calcium absorption Peptide-Ca chelates have emerged as promising calcium supplements in recent years. Hericium erinaceus (HE) derived calcium-binding peptides (CBP) have been prepared by our group previously. However, the amino acid (AA) sequences of these peptides are not yet clear, and which peptides have a higher affinity for Ca 2+ require investigation. In the present study, the most effective CBP from HE were screened based on molecular docking and in silico prediction. The nonapeptide-Ca chelate derived from HE was prepared, and its microstructure, binding mechanism, stability and promoting effect on calcium absorption were evaluated. The result showed that, following purification by ultrafiltration and anion-exchange chromatography, the F 33 sub-fraction with the highest calcium-binding rate (CBR) was obtained. The nonapeptide WYEEGTDKA identified in F 33 was selected. The peptide exhibited the highest affinity for Ca 2+ and calcium sensing receptor (CaSR) and had good water-solubility, no toxicity and less cleavage sites by digestive enzymes. Characterization results indicated that WYEEGTDKA-Ca consisted of compact plates and regular spherical structures. After chelation, the endogenous fluorescence of WYEEGTDKA was reduced, and its secondary structure (α-Helix and β-Sheet) was altered. The W, E, T, D, K and A residues were involved in the chelation, providing -COO-, N-H, and C=O groups to form ionic or coordinate bonds with Ca 2+ . WYEEGTDKA-Ca demonstrated good heat stability and sensitivity to low pH. WYEEGTDKA-Ca retained most of the calcium during stimulated digestion. WYEEGTDKA-Ca exhibited better promoting effects on calcium absorption compared to casein phosphopeptides-Ca (CPP). Thus, WYEEGTDKA-Ca was a promising calcium supplement derived from HE. Hericium erinaceus (HE) protein was hydrolyzed to obtain HE protein hydrolysates with calcium-binding ability. The hydrolysates were separated by ultrafiltration and anion-exchange chromatography to obtain sub-fractions with potent calcium-binding abilities. The amino acid sequences of these sub-fractions were identified by LC-EIS-MS/MS. The identified peptides were further screened by molecular docking based on the binding energy scores of peptide-Ca 2+ and peptide-CaSR, leading to the selection of WYEEGTDKA. WYEEGTDKA-Ca chelate was prepared. The microstructure, particle size, zeta potential, binding mechanisms, stability, and calcium absorption-promoting effects of the WYEEGTDKA-Ca were subsequently analyzed. In this study, traditional methods coupled with bioinformatics tools were applied in the screening of CBP, broadening the research methodologies in this field. This study provides a theoretical basis for the research and development of HE peptide-Ca chelates.