title: Oxinobactin and sulfoxinobactin, abiotic siderophore analogues to enterobactin involving 8-hydroxyquinoline subunits: thermodynamic and structural studies.
abstract: The synthesis of two new iron chelators built on the tris-l-serine trilactone scaffold of enterobactin and bearing a 8-hydroxyquinoline (oxinobactin) or 8-hydroxyquinoline-5-sulfonate (sulfoxinobactin) unit has been described. The X-ray structure of the ferric oxinobactin has been determined, exhibiting a slightly distorted octahedral environment for Fe(III) and a Δ configuration. The Fe(III) chelating properties have been examined by potentiometric and spectrophotometric titrations in methanol-water 80/20% w/w solvent for oxinobactin and in water for sulfoxinobactin. They reveal the extraordinarily complexing ability (pFe(III) values) of oxinobactin over the p[H] range 2-9, the pFe value at p[H] 7.4 being 32.8. This was supported by spectrophotometric competition showing that oxinobactin removes Fe(III) from ferric enterobactin at p[H] 7.4. In contrast, the Fe(III) affinity of sulfoxinobactin was largely lower as compared to oxinobactin but similar to that of the ligand O-TRENSOX having a TREN backbone. These results are discussed in relation to the predisposition by the trilactone scaffold of the chelating units. Some comparisons are also made with other quinoline-based ligands and hydroxypyridinonate ligand (hopobactin).
authors.affiliation: Université Joseph Fourier-Grenoble I , Département de Chimie Moléculaire, Laboratoire de Chimie Inorganique Rédox, UMR-5250, ICMG FR-2607, CNRS, BP 53, F-38041 Grenoble Cedex, France.
authors.forename: Amaury
authors.initials: A
authors.lastname: du Moulinet d'Hardemare
authors.forename: Gisèle
authors.initials: G
authors.lastname: Gellon
authors.forename: Christian
authors.initials: C
authors.lastname: Philouze
authors.forename: Guy
authors.initials: G
authors.lastname: Serratrice
mesh_terms: D018360:Crystallography, X-Ray; D004758:Enterobactin / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D015125:Oxyquinoline / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D013438:Sulfhydryl Compounds; C540156:oxinobactin; D004758:Enterobactin; D015125:Oxyquinoline