A new iron-binding protein isolated from intestinal mucosa.

A new iron-binding protein contained in guinea pig intestinal mucosa has been purified to homogeneity. The protein has a molecular weight of 78,000 in a nondissociating system and 43,000 in SDS-gel electrophoresis. It binds approximately 2 moles of iron per mole with a formation constant of 10(19) at pH 7. It is distinguished from transferrin and lactoferrin by differences on DEAE-Sephadex chromatography and spectroscopy and by its failure to cross-react with antisera to these other iron-binding proteins.