Iron binding to apoferritin: A fluorescence spectroscopy study

Abstract

Iron is stored in animal tissues in the ferric state as the micellar core of ferritin; however it appears that a prerequisite for both iron uptake and mobilization is its reduction to the ferrous state [l] . The currently accepted models of iron incorporation into apoferritin assume binding as Fe’+ and a subsequent oxidation catalysed by the protein [2]. While the catalytic action of apoferritin is well documented, no information is available regarding the metal binding step. Fluorescence spectroscopy seemed a very useful tool to investigate this aspect of the problem. In fact binding of the ferrous salt to the protein can be inferred from the quenching of the intrinsic fluorescence of apoferritin. During the course of the study information was also obtained on the structure of apoferritin and its isolated subunits with respect to the nature of the environment of the fluorescent residues.