title: Photoreactivity of iron(III)-aerobactin: photoproduct structure and iron(III) coordination.
abstract: UV photolysis of the ferric aerobactin complex results in decarboxylation of the alpha-hydroxy carboxylic acid group of the central citrate moiety of aerobactin. The structure determination of the photooxidized ligand shows that decarboxylation occurs at the citrate moiety forming a 3-ketoglutarate moiety. Proton and carbon-13 NMR establish the presence of keto and enol tautomers of the apo-photoproduct, with the enol form prevailing in water. The photoproduct retains the ability to coordinate iron(III). The values of the ligand protonation constants, the pKa of the Fe(III)-ligand complex, and the Fe(III) stability constant of the photoproduct of aerobactin are all close to those of aerobactin. CD spectroscopy suggests that the chirality of the ferric complexes of aerobactin and its photoproduct are similar. Like aerobactin, the photoproduct promotes iron acquisition by the source bacterium, Vibrio sp. DS40M5.
authors.affiliation: Departments of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA.
authors.forename: Frithjof C
authors.initials: FC
authors.lastname: Küpper
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Carrano
authors.forename: Jens-Uwe
authors.initials: JU
authors.lastname: Kuhn
authors.forename: Alison
authors.initials: A
authors.lastname: Butler
mesh_terms: D002244:Carbon / Q000737:chemistry; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D006877:Hydroxamic Acids / Q000737:chemistry*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry*; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics; D014733:Vibrio / Q000378:metabolism
chemical_list: D006877:Hydroxamic Acids; D008024:Ligands; D008670:Metals; D011522:Protons; C031819:aerobactin; D002244:Carbon; D007501:Iron; D010100:Oxygen