Pseudobactin
Pseudobactin is a microbial siderophore produced by a strain of Pseudomonas. The ferrated compound was crystallized (C42H57N12O16Fe·13H2O) and structure determined by x-ray diffraction. The iron-binding ligands are a hydroxymate moiety from N d-hydroxyornithine, an a-hydroxy acid from B-hydroxyaspartic acid, an o-dihydroxy aromatic group (catechol) from the quinoline derivative.
Highlighting Features
Show central Fe and nearest neighbors: 6 OThis model shows the near-perfect octahedral coordination of the central Fe atom, with six oxygens as the apices of the octahedron. The symmetry of the central Fe atom with its nearest neighbors is one of the key factors in chelate stability. In spacefilling mode, this model show that the central Fe atom is nearly completely concealed by coordinating oxygens. No coordination by additional water (H2O) or hydroxide (OH-) is permitted in this structure, which adds to the stability of this chelate.
The quinoline moiety gives unferrated pseudobactin a fluorescent yellow-green color. Upon addition of ferric salts and formation of ferric pseudobactin, the color of the compound is reddish brown.
M. Teintze, MB Hossain, CL Barnes, J Leong, and D. van der Helm. 1981. Structure of ferric pseudobactin, a siderophore from a plant growth promoting Pseudomonas. Biochem. 20:6446-6457.