Biophysical and in vitro absorption studies of iron chelating peptide from barley proteins

Isothermal titration calorimetry (ITC) and tandem mass spectrometry (MS/MS) were used to study the interaction between Fe2+ and the heptapeptide (SVNVPLY) from barley protein hydrolysate under physiological pH. The peptide showed an ability to form complexes with Fe2+ spontaneously, with a binding constant reaching 107 L mol−1. Two peptide binding sites were identified and amino acid residues like Leu, Val, Pro and Tyr have been recognized as critical for iron coordination. The capacity for the heptapeptide and its shorter tripeptide analogue (VPL) to improve iron absorption was studied in vitro using Caco-2 cells. The cell uptake increased 4 times for the Fe2+-SVNVPLY complex after pepsin-pancreatin digestion compared to the iron sulfate salt. The ferritin formation in the Caco-2 cells was also significantly enhanced when iron was chelated to the peptides. This research suggests a potential application of barley peptides as dietary supplements to improve iron absorption.