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Synthesis and Iron‐Binding Properties of Protochelin, the Tris (catecholamide) Siderophore of Azotobacter vinelandii
Author(s) -
Dubme AnneKathrin,
Hider Robert Charles,
Khodr Hicham Hussein
Publication year - 1997
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19971300726
Subject(s) - azotobacter vinelandii , chemistry , siderophore , molybdate , tris , protonation , hydroxide , inorganic chemistry , dissolution , ferric , aqueous solution , stability constants of complexes , nuclear chemistry , medicinal chemistry , organic chemistry , nitrogen , biochemistry , nitrogenase , ion , nitrogen fixation , gene
Abstract Protochelin, the tris(catecholamide) siderophore recently identified in the culture medium of A. vinelandii , can be synthesised by coupling of suitably protected azotochelin and aminochelin derivatives in preparative yields, Based on the ligand protonation constants of p K 1 = 6.67, p K 2 = 8.09 and p K 3 = 9.68, the proton‐independent stability constant for ferric protochelin could be estimated to be 10 44.6 . The solubilisation of Fe III hydroxide by protochelin has been investigated spectrophotometrically in aqueous solution at pH = 7. Since the production of protochelin by A. vinelandii depends on high molybdate levels in the growth medium, the studies have been carried out in the presence as well as in the absence of an equimolar amount of molybdate. Although the protochelin promoted dissolution of Fe III hydroxide is delayed significantly in presence of molybdate, the effect is far less pronounced than the one observed for azotochelin, the bis(catecholamide) siderophore of A. vinelandii.