Sensitivity of β-casein phosphopeptide-iron complex to digestive enzymes in ligated segment of rat duodenum

Abstract

Binding iron to the phosphorylated β(1-25) peptide derived from β-casein improves iron bioavailability in the rat. The aim of the present work was to learn how injected β(1-25) and iron-β(1-25) complex behave in the duodenum of rats using the technique of intestinal ligation in situ and reversed-phase (RP)-high performance liquid chromatography-electrospray mass spectrometry analysis of the lumen contents. The results demonstrate that β(1-25) is sensitive to digestive enzymes including proteases/peptidases and phosphatases during duodenal transit. The lumen contents of rats perfused with iron free β(1-25) contained all peptidic sequences derived from β(1-25). In contrast, the phosphorylated part of β(1-25) [i.e., β(15-24)] was not detected in lumen of rats perfused with iron-β(1-25) complex.