Abstract by Ryan Smith
Chemistry and Biochemistry
Effect of chelation by Calcein on iron release into the Labile Iron Pool
Free iron in cells can react with O2 to produce superoxide, peroxide and hydroxyl radicals known as Reactive Oxygen Species (ROS). Remarkably, the cell has a free iron pool known as the Labile Iron Pool (LIP) that supplies iron to requiring enzymes. Measurements of the LIP range between 0.1 – 10 micromolar and are often measured via a fluorescence assay known as the Calcein Assay. Calcein is added to cells and binds Fe2+, quenching fluorescence. Then a specific Fe2+ chelator is added, and the increase of fluorescence is attributed to cytosolic Fe2+. We propose that if ferritin releases Fe2+ during this cellular assay, the LIP will show an artificially high iron content. I report in vitro reactions of Calcein and ferritin in the presence of physiologically relevant reducing agents to determine how much iron is released from ferritin under conditions similar to the cellular assay.