Identification of iron-chelating peptides from Pacific cod skin gelatin and the possible binding mode

Abstract

Pacific cod skin gelatin was hydrolyzed under optimized conditions (trypsin, 240min) to generate iron-chelating peptides. Gelatin tryptic hydrolysates were purified by immobilized metal affinity chromatography and reversed phase high performance liquid chromatography. Three novel iron-chelating peptides identified by LC-HRMS/MS were GPAGPHGPPGKDGR, AGPHGPPGKDGR and AGPAGPAGAR, which exhibited high affinity to ferrous ions. The iron-peptide complexation, investigated by ESI-MS and FTIR spectroscopy, showed that the three peptides bound with iron mainly at the ratio of 1:1. Among the groups of the three peptides, the amino and carboxylate terminal groups and peptide bond from peptide backbone, as well as the amino and imine from arginine side chain were involved in the complexation. Moreover, several amino acid side chain groups of GPAGPHGPPGKDGR and AGPHGPPGKDGR, including amino (Lys), imine (His) and carboxylate (Asp), supplied additional iron binding sites. This study suggests a potential application of gelatin-derived peptides as novel carriers to combat iron deficiency.