Structural dependence of Mn complexation by siderophores: Donor group dependence on complex stability and reactivity
Structural dependence of Mn complexation by siderophores: Donor group dependence on complex stability and reactivity
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DOI：
10.1016/j.gca.2012.04.006
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发表时间：
2012-07-01
影响因子：
5
通讯作者：
Duckworth, Owen W.
中科院分区：
文献类型：
--
作者：
Harrington, James M.;Parker, Dorothy L.;Duckworth, Owen W.
铁载体传统上被认为只参与铁（III）的生物地球化学循环。然而，这种模式忽略了铁载体在其他微量金属（如Mn、Co、Mo和v）循环中可能发挥的不同作用。最近的研究表明，铁载体与Mn（III）形成的配合物具有高稳定常数，在某些情况下高于相应的Fe（III）配合物。在此，我们报道了用x射线光谱技术对溶解的铁(III)-和Mn(III)-铁载体配合物和两种pyoverdin型铁载体进行结构分析。此外，Mn(III)-pyoverdin（PaA）和Mn(III)-rhizoferrin配合物的稳定性常数分别为log beta(111) = 47.5 +/- 0.3和log beta(110) = 29.8 +/- 0.3。Fe(III)-和Mn(III)-配合物与各种铁载体的热力学稳定性和溶液结构的比较证明了供体基团身份、铁载体结构和配合物形成强度之间的关系。与Fe（III）相比，Rhizoferrin和两种混合片段pyoverdins结合对Mn（III）的亲和力更高，这可能是因为结合片段的组成使它们能够更好地适应Jahn-Teller畸变。相比之下，铁（III）与含有羟基和儿茶酚酸基团的铁载体形成相对稳定的配合物，更刚性的供体基团形成五元螯合环。(C) 2012 Elsevier Ltd.版权所有。
Siderophores traditionally have been viewed as solely being involved in the biogeochemical cycling of Fe(III). This paradigm, however, ignores the diverse roles siderophores may play in the cycling of other trace metals, such as Mn, Co, Mo, and V. Recent work has shown that siderophores form complexes with high stability constants with Mn(III), which are in some cases higher than that of the corresponding Fe(III) complex. Herein, we report on a structural analysis of the dissolved Fe(III)- and Mn(III)-siderophore complexes of rhizoferrin and two pyoverdin-type siderophores using X-ray spectroscopic techniques. Additionally, the stability constants of the Mn(III)-pyoverdin(PaA) and Mn(III)-rhizoferrin complexes have been quantified as log beta(111) = 47.5 +/- 0.3 and log beta(110) = 29.8 +/- 0.3, respectively. Comparisons of thermodynamic stability and solution structures of Fe(III)- and Mn(III)-complexes with a variety of siderophores demonstrate the relationship between donor group identity, siderophore structure, and strength of complex formation. Rhizoferrin and two mixed-moiety pyoverdins bind with a higher affinity for Mn(III) than Fe(III), possibly because of binding moiety composition which makes them better able to accommodate Jahn-Teller distortion. In contrast, Fe(III) forms complexes of higher relative stability with siderophores that contain hydroxamate and catecholate moieties, more rigid donor groups that form five-membered chelate rings. (C) 2012 Elsevier Ltd. All rights reserved.