Identification and characteristics of iron-chelating peptides from soybean protein hydrolysates using IMAC-Fe3+.

The iron-chelating peptides from soybean protein hydrolysates (SPH) were investigated using immobilized metal affinity chromatography (IMAC). The results demonstrated that SPH could absorb on the IMAC-Fe(3+) column, while the capability of the binding iron was different in SPH (10-30 kDa), SPH (3-10 kDa), and SPH (1-3 kDa). The highest binding amount on the column occurred with SPH (10-30 kDa). With the IMAC method, the iron-chelating peptides were shown to be formed at pH lower than 5.5, and they were not affected by NaCL with the concentration between 0.1 mol/L and 1 mol/L, while the iron-chelating peptides could be partially disrupted by 0.02 mol/L Na(2)HPO(4) at pH 8.0. Furthermore, the iron-chelating peptides were identified with reversed phase (RP)-HPLC, SDS-PAGE, and MALDI-TOF MS/MS. The binding characteristics of the SPH on IMAC-Fe(3+) and the sequences of the iron-chelating peptides revealed that binding sites between SPH and iron might be the carboxyl groups of Glu and Asp residues.