Catecholates, siderophores

TRENSerCAM (20) TRENGIuCAM (21) TRENLysCAM (22) Fig. 10. TREN family of catechol siderophore mimics. 

The exchange of iron from transferrin to desferrioxamine B (4), some catecholate siderophores, and some hydroxypyridinone-based siderophore mimics has been investigated (139,189,190). Turcot et al. found that at concentrations similar to those that would be observed in biological settings or clinical treatments,... 

For other catecholate siderophores see di-/tri-aminoalkane (Sect. 3.2) and citric acid (Sect. 4.3) derivatives below for a review see (38). 

For other catecholate siderophores, see the peptide-based siderophores above (Sect. 2.7) and the citric acid derivatives below (Sect. 4.3) for a review on syntheses, see (24), for a general review, 38). 

Achromobactin (60, Fig. 18) is produced by Erwinia chrysanthemi in addition to chrysobactin (see above under the catecholate siderophores, Sect. 2.7). It has two chiral centers, a L-Dab unit and the central citric acid C-atom (not determined) (249). Recently, achromobactin was also found to be produced by Pseudomonas syringae (30b), a very versatile bacterial species (see pyoverdin, Sect. 2.1, and yersiniabactin. Sect. 5). 

Barelmann I, Meyer JM, Taraz K, Budzikiewicz H (1996) Cepaciachelin, a New Catecholate Siderophore from Burkholderia Pseudomonas) cepacia. Z Naturforsch 51c 627... 

Budzikiewicz H (2004) Siderophores of the Pseudomonadaceae sensu stricto (Fluorescent and Non-fluorescent Pseudomonas spp.). Progr Chem Org Nat Prod 87 81 Budzikiewicz H (2004) Bacterial Catecholate Siderophores. Mini-Rev Org Chem 1 163 Budzikiewicz H (2005) Bacterial Citrate Siderophores. Mini-Rev Org Chem 3 119 Budzikiewicz H (2006) Bacterial Aromatic Sulfonates - a Bucherer Reaction in Nature Mini-Rev Org Chem 3 93... 

Budzikiewicz H, Bossenkamp A, Taraz K, Pandey A, Meyer JM (1997) Corynebactin, a Cyclic Catecholate Siderophore from Corynebacterium glutamicum ATCC 14067 (Brevi-bacterium sp. DSM 20411). Z Naturforsch 52c 551... 

May JJ, Wendrich TM, Mahariel MA (2001) The dhb Operon of Bacillus subtilis Encodes the Biosynthetic Template for the Catecholic Siderophore 2,3-Dihydroxybenzoate-glycine-threonine Trimeric Ester Bacillibactin. J Biol Chem 276 7209... 

Muller SI, Valdebenito M, Hantke K (2009) Sahnochelin, the Long-overlooked Catecholate Siderophore of Salmonella. Biometals 22 691... 

Tindale AE, Mehrotra M, Ottem D, Page WJ (2000) Dual Regulation of Catecholate Siderophore Biosynthesis in Azotobacter vinelandii by Iron and Oxidative Stress. Microbiology 146 1617... 

Yamamoto S, Okujo N, Fujita Y, Saito M, Yoshida T, Shinoda S (1993) Structures of Two Polyamine-containing Catecholate Siderophores from Vibrio fluvialis. J Biochem 113 538... 

In contrast to the tris-catecholate siderophores, which form charged iron(III) complexes, the hydroxamate-based ferri-siderophore complexes are electrically neutral, which may influence their transport through biological membranes. 

The emphasis on the study of hemoproteins and the iron-sulfur proteins often distracts attention from other iron proteins where the iron is bound directly by the protein. A number of these proteins involve dimeric iron centres in which there is a bridging oxo group. These are found in hemerythrin (Section 62.1.12.3.7), the ribonucleotide reductases, uteroferrin and purple acid phosphatase. Another feature is the existence of a number of proteins in which the iron is bound by tyrosine ligands, such as the catechol dioxygenases (Section 62.1.12.10.1), uteroferrin and purple acid phosphatase, while a tyrosine radical is involved in ribonucleotide reductase. The catecholate siderophores also involve phenolic ligands (Section 62.1.11). Other relevant examples are transferrin and ferritin (Section 62.1.11). These iron proteins also often involve carboxylate and phosphate ligands. These proteins will be discussed in this section except for those relevant to other sections, as noted above. 

Catecholate Siderophores. Simple Catechol Complexes. As noted earlier, the common siderophore for enteric bacteria is the tricatechol, enterobactin (Figure 4). In order to perfect synthetic and... 

In contrast to the hydroxamate siderophores, little or nothing is known about the stability constant for the catechol siderophore, entero-bactin. Prior to determining the formation constant of enterobactin (for which hydrolysis of the ligand presents special problems), the reaction of catechol itself with ferric ion has been investigated (31). 

The obvious method of choice is to model novel structures on natural hydroxamate and catechol siderophores which possess extremely high affinities for iron(III) [35], Hydroxamates possess many advantages for iron(III) chelation, as was outlined in the section on bidentate ligands. However, they tend to possess a low oral activity. Nevertheless, a number have been investigated, including rhodotorulic acid [36], synthetic hexadentate [37] and polymeric hydroxamates [38]. None has proved superior to DFO (Structure 2, Scheme IB). 

---