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Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium

Abstract

The calcium-chelating peptide is considered to have the ability to improve calcium absorption. In this study, Pacific cod skin gelatin hydrolysates treated by trypsin for 120 min exhibited higher calcium-chelating activity. Sequential chromatography, involving hydroxyapatite affinity chromatography and reversed phase high performance liquid chromatography, was used for the purification of calcium-chelating peptides. Two novel peptides with the typical characteristic of collagen were sequenced as GDKGESGEAGER and GEKGEGGHR based on LC-HRMS/MS, which showed high affinity to calcium. The calcium-peptide complexation was further characterized by ESI-MS (MS and MS/MS) and FTIR spectroscopy. Results showed that the complexation of the two peptides with calcium was conducted mainly at the ratio of 1:1. The amino terminal group and peptide bond of the peptide backbone as well as the amino of lysine side chain and the carboxylate of glutamate side chain were the possible calcium binding sites for the two peptides. Meanwhile, several amino acid side chain groups, including the hydroxyl (Ser) and carboxylate (Asp) of GDKGESGEAGER and the imine (His) of GEKGEGGHR, were crucial in the complexation. The arginine residue in GEKGEGGHR also participated in the calcium coordination. Additionaly, several active fragments with calcium-chelating activity were obtained by MS/MS spectra, including GDKGESGEAGE, GEAGER, GEK, EKG and KGE. This study suggests that gelatin-derived peptides have the potential to be used as a calcium-chelating ingredient to combat calcium deficiency.

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Publication details

The article was received on 08 Jul 2017, accepted on 06 Oct 2017 and first published on 09 Oct 2017


Article type: Paper
DOI: 10.1039/C7FO01014A
Citation: Food Funct., 2017, Accepted Manuscript
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    Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium

    W. Wu, B. Li, H. Hou, H. Zhang and X. Zhao, Food Funct., 2017, Accepted Manuscript , DOI: 10.1039/C7FO01014A

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