3.3 Summary of Section 3

1. E. coli has a remarkable method of obtaining iron from its environment, which involves the use of very powerful iron chelators, called siderophores.

2. One siderophore in particular, enterobactin, forms an extremely stable complex with iron(III).

3. The high stability of this complex is due partly to the rigid, preorganised structure of the ligand, and partly to the iron(III) being the correct size and charge to be chelated effectively by enterobactin.

4. Enzymes called esterases are able to catalyse the hydrolysis of the iron(III)–enterobactin complex and so release iron.