Transferrin (TF)

Transferrin is a blood plasma protein for iron ion delivery that, in humans, is encoded by the TF gene. Transferrin is a glycoprotein that binds iron very tightly but reversibly. Although iron bound to transferrin is less than 0.1% (4 mg) of the total body iron, it is the most important iron pool, with the highest rate of turnover (25 mg/24 h). Transferrin has a molecular weight of around 80 kiloDaltons and contains 2 specific high-affinity Fe(III) binding sites.

The affinity of transferrin for Fe(III) is extremely high (1023 M-1 at pH 7.4)[citation needed] but decreases progressively with decreasing pH below neutrality.In humans, transferrin consists of a poly peptide chain containing 679 amino acids. It is a complex composed of alpha helices and beta sheets to form two domains.