IRON-BINDING AND AUTOREDUCTION BY CITRATE - ARE THESE INVOLVED IN SIGNALING BY IRON REGULATORY PROTEIN-1

Ferric ions bind to citrate and undergo an autoreduction to form a fer rous-citrate complex, greatly increasing the redox activity of the iro n complex. Ferrous ions and citrate are also essential for the enzymic activity of aconitase. Aconitase, with its iron-sulphur cluster has a versatile structure which allows it to act as an iron regulatory prot ein (IRP-1). The purpose of this study was to see whether iron binding , and its autoreduction by citrate, could play a physiological signall ing role in iron regulation. Significant amounts of ferrous ions were associated with citrate, when measured using ferrozine, however, these did not appear to activate iron-requiring aconitase.