Transferrin is a glycoprotein with a relative mass of about 80,000 Da
containing two high affinity binding sites. Plasma transferrin is
involved in transporting iron from the alimentary tract to the tissues
of the body. Its extremely high binding affinity (10
22 dm
3mol
-1) means
that it can also outcompete many microorganisms for iron, acting as a
bacteriostat.
The two metal-binding sites on transferrin are similar but not
identical and function independently. In the absence of iron
transferrin is capable of binding other metal ions such as aluminium,
chromium, cobalt, copper, manganese, vanadium as well as plutonium and
europium. Similar proteins are found in milk (lactoferrin) and eggs
(ovotransferrin).
