Abstract
Summary: The reaction of αs1- and β-casein with ferrous ions and O2has been studied. It has been found that phosphoseryl residues present in these proteins rapidly catalyse the oxidation of iron from the ferrous to the ferric state with the formation of stable ferric-phosphoprotein complexes and the consumption of the theoretical amount of O2. When, however, the phosphoseryl residues occurred in groups, the formation of ferric complexes was accompanied by uptakes of O2in quantities significantly in excess of that required for the oxidation of ferrous to ferric iron.The significance of these findings is discussed in relation to hypotheses which have been advanced concerning the possible biological function of phosphoprotein.