Kinetics of Iron-Siderophore Systems

Additional relevant details of the kinetics and mechanisms of iron chelation reactions may be found in other recent reviews (10,22,134,160,161). 

The kinetics and mechanism of iron-siderophore complex formation are influenced by the oxidation state and composition of the first coordination shell of iron. The iron sequestration 

These general comments regarding iron sequestration kinetics can be placed in the context of the Eigen-Wilkins mechanism for complexation (135). Initial complex formation proceeds by way of the formation of an encounter complex, Fe(H20)g+ L, 

Charge density is known to influence water exchange rates at a metal center (160). Since OH- is a stronger donor than OH2, this 

The implications of these mechanistic studies for our understanding of environmental iron sequestration by siderophores is as follows. The hydroxyl containing aqua ferric ions will tend to form ferri-siderophore complexes more rapidly than the hexaaqua ion and ferrous ion will be sequestered more rapidly than the ferric ion. However, once in a siderophore binding site the ferrous ion will be air oxidized to the ferric ion, due to the negative redox potentials (see Section III.D). This also means that Fe dissolution from rocks will be influenced by mineral composition (other donors in the first coordination shell) as well as surface reductases in contact with the rock, and of course surface area (4,13). 

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