Siderophore properties

A number of catechols of lower molecular weight, which have siderophoric properties, have been isolated. Examples are shown in Figure 46. All organisms synthesizing enterobactin also form 2,3-dihydroxybenzoylserine, while a number of related species are also present. One of these, itoic acid, from Bacillus subtilis was the first phenolate siderophoric ligand to be isolated.1185... 

Chattaraj PK, Parr RG (1993) Density Functional Theory of Chemical Hardness. 80 11-26 Cheh AM, Neilands JP (1976) The j -Aminoevulinate Dehydratases Molecular and Environmental Properties. 29 123-169 Chimiak A, Neilands JB (1984) Lysine Analogues of Siderophores. 58 89-96 Christensen JJ, see Izatt RM (1973) 16 161-189... 

The Ee " chelating properties of exochelin MN (17) were investigated in detail (pK values, chelation constants, redox equilibria, etc.) (87). In one publication (128) siderophores from Mycobacterium tuberculosis otherwise referred to as carboxymycobactins (see below Sect. 2.8) were also named exochelins. 

Boukhalfa H, Reilly SD, Michalczyk R, Iyer S, Neu P (2006) Iron (III) Coordination Properties of a Pyoverdin Siderophore Produced by Pseudomonas putida ATCC 33015. Inorg Chem 45 5607... 

Demange P, Wendenbaum S, Linget C, Bateman A, MacLeod J, Dell A, Albrecht AM, Abdallah MA (1989) Pseudomonas Siderophores Structure and Physicochemical Properties of Pyoverdins and Related Peptides. Second Forum on Peptides 174 95... 

Dhungana S, Miller MJ, Dong L, Ratledge C, Crumbliss AL (2003) Iron Chelation Properties of an Extracellular Siderophore Exochelin MN. J Am Chem Soc 125 7654... 

Jalal MAF, Love SK, van der Hehn D (1986) Siderophore Mediated Iron(III) Uptake in Gliocladium virens. 1. Properties of cw-Fusarinine, trani-Fusarinine, Dimerum Acid, and their Ferric Complexes. J Inorg Biochem 28 417... 

Kameyama T, Takahashi A, Kurasawa S, Ishizuka M, Okami Y, Takeuchi T, Umezawa H (1987) Bisucaberin, a New Siderophore, Sensitizing Tumor Cells to Macrophage-mediated Cytolysis. I. Taxonomy of the Producing Organism, Isolation and Biological Properties. J Antibiotics 40 1664... 

The physical and coordination chemistry of hydroxamate-based iron chelators, their thermodynamic, kinetic, structural, spectroscopic and surface properties, have been extensively reviewed Therefore, only selective aspects that are relevant for the design of biomimetic siderophore analogs will be discussed. 

The high efficiency and selectivity of the natural siderophores in binding iron(lll) inspired attempts to develop siderophore analogs with improved iron-scavenging properties amenable for chelation therapy. A most pertinent example is desferrioxamine B (DFO), where low patient compliance generates the need for developing oral means of administration for... 

Kraemer, S.M. Hering, J.G. (1997) Influence of solution saturation state on the kinetics of ligand-controlled dissolution of oxide phases. Geochim. Cosmochim. Acta 61 2855-2866 Kraemer, S.M., Xu, J., Raymond, K.N. Spo-sito, G. (2002) Adsorption of Pb(II) and Eu(III) by oxide minerals in the presence of natural and synthetic hydroxamate sidero-phores. Environ. Sd. Technol. 36 1287-1291 Kraemer, S.M. Cheah, S.-F. Zapf, R. Xu, J. Raymond, KN. Sposito, G. (1999) Effect of hydroxamate siderophores on Fe release and Pb(II) adsorption by goefhite. Geochim. Cosmochim. Acta 63 3003—3008 Kratohvil, S. Matijevic, E. (1987) Preparation and properties of coated uniform colloidal partides. I. Aluminum (hydrous) oxide on hematite, diromia, and titania. Adv Ceram. Mater. 2 798-803... 

Bacterial siderophores are another class of widespread toxins produced by bacteria. On land, mycobactins and exophilins are the best-known representatives. Those found in the sea, aquachelins, marinobactins, anguibactin, vulnibactin, and aerobactin (Table 12.3.1) are amphiphilic. This is a property that has received great attention for drug delivery problems and in relation to recognition processes (Testa 2000), devising efBcient algorithms for computer calculation (Fisher 2000). 

Investigations of the kinetics of the reaction of these new siderophores with iron-saturated transferrin showed a rapid formation of a ternary complex with transferrin, followed by a slow step in which the ferric siderophore was released from the apoprotein. Weitl et al.257 have evaluated the ferric-chelating properties of several of these siderophores and found the following order of effectiveness for removing iron from transferrin enterobactin > MECAMS > MECAM > LICAMS > DFOA > TRIM-CAMS. 

Ligand 3.147 is part of the class of siderands (synthetic siderophores), and displays further useful properties such as stability towards oxidation of the catechol binding sites and hydrolysis resistance. This represents one of the few examples where man-made molecules are more effective than their natural precursors. 

Amidocryptands were until recently unknown in anion circles [39-41,54-56], However, Raymond and coworkers previously synthesized catechol-based amidocryptands as models for siderophores [57], The appeal of polyamide cryptands over polyamines is related to their solution properties, namely the former class of ligands is less susceptible... 

The general properties of siderophores have been described extensively (2), and up-to-date lists of the individual compounds, their sources from aerobic and facultative aerobic species, and their properties have been published (3,4, 5). (Porphyrin Products, P. O. Box 31, Logan, UT 84321, sell a limited number of siderophores.) The earlier literature on iron assimilation by microbes, including enteric species, may be found elsewhere (6,7). For information on the chemical constitution and physiological role of the outer membrane of enteric bacteria, the reader is referred to Nakae and Nikaido (8). 

Figure 13. Schematic of the organization and properties of siderophore receptors in Escherichia coli K-12.

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