Enterobactin vanadium complex

It may be there to poison predators.614 The vanadium-accumulating species also synthesize several complex, yellow catechol-type chelating agents (somewhat similar to enterobactin Fig. 16-1) which presumably complex V(V) and perhaps also reduce it to V(III).615 Vanadium is also accumulated by other marine organisms and by the mushroom Amanita muscaria. 

Three other metals, namely, copper, vanadium, and molybdenium, possess appreciable affinities for siderophores. It is possible that siderophores or siderophore-like molecules are involved in the microbial transport of these metals. Copper(II) forms stable complexes with hydroxamate siderophores (for instance, schizokinen, desferriox-amine B. and desfeirithiocin) and catechol siderophores (for instance, enterobactin). However, copper(II), unlike iron(III), also possesses a high affinity for amino acids and small peptides, and this property renders it unlikely that copper uptake is dependent on siderophore-medi-ated transport. 

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