Küpper Frithjof C, Carrano Carl J, Kuhn Jens-Uwe, Butler Alison
Departments of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA.
Inorg Chem. 2006 Jul 24;45(15):6028-33. doi: 10.1021/ic0604967.
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.
铁载体气杆菌素复合物的紫外光解导致气杆菌素中心柠檬酸部分的α-羟基羧酸基团脱羧。光氧化配体的结构测定表明，脱羧发生在柠檬酸部分，形成3-酮戊二酸部分。质子和碳-13核磁共振确定了脱辅基光产物的酮式和烯醇式互变异构体的存在，其中烯醇式在水中占主导。光产物保留了与铁（III）配位的能力。气杆菌素光产物的配体质子化常数、铁（III）-配体复合物的pKa以及铁（III）稳定性常数的值均与气杆菌素的相近。圆二色光谱表明，气杆菌素及其光产物的铁复合物的手性相似。与气杆菌素一样，光产物促进了源细菌嗜盐弧菌DS40M5对铁的摄取。
