Spectroscopic Characterization of the Active FeIIIFeIII and FeIIIFeII Forms of a Purple Acid Phosphatase Model System
Spectroscopic Characterization of the Active FeIIIFeIII and FeIIIFeII Forms of a Purple Acid Phosphatase Model System
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DOI：
10.1021/ic301347t
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发表时间：
2012-11-19
影响因子：
4.6
通讯作者：
Zajaczkowski-Fischer, Marta
中科院分区：
文献类型：
--
作者：
Comba, Peter;Gahan, Lawrence R.;Zajaczkowski-Fischer, Marta
设计并合成了两个新的双核配体(H3L2和HL3)，它们是一个著名的双核配体(HL1)的衍生物，其中两个双甲基甲胺连接到一个桥联酚，在两个吡啶基团上带有氢键供体基团。这些配体的设计表明，它们将导致具有稳定磷酸酯底物的潜力的双核配合物作为单齿而不是桥联配体。报道了二铁配合物[Fe-2(III)(H_2L_2)(OH)(4+)和[Fe-2(III)(L-3)(OH)(OH)(2)](4+)](4+)，用分光光度滴定、紫外-可见光谱、红外光谱、核磁共振、电子顺磁共振和穆斯堡尔谱对其进行了表征。除了部分还原的异价配合物[(FeFeII)-Fe-III(L-3)(OH)(OH2)(2)](3+)外，还研究了二铁体系的磷酸酶活性，结果表明，这些络合物能催化活性磷酸二酯底物BDNPP和相应的磷酸单酯底物DNPP(二硝基苯磷酸)。结果表明，二次相互作用确实导致了磷酸酶活性的提高和磷酸单酯酶催化剂的活性。有趣的是，基于HL3的络合物的异价形式比二铁络合物更有效，这也被讨论过。
Two new dinucleating ligands (H3L2 and HL3), derivatives of a well-known dinucleating ligand (HL1) with two bis-picolylamine sites connected to a bridging phenolate, with hydrogen-bonding donor groups at two of the pyridine moieties were designed and synthesized. Design of these ligands suggests that they will lead to dinuclear complexes with potential to stabilize phosphoester substrates as monodentate rather than bridging ligands. We report the diferric complexes [Fe-2(III)(H2L2)(OH)(4+) and [Fe-2(III)(L-3)(OH)(OH2)(2)](4+), which have been characterized by spectrophotometric titrations, UV-vis, IR, NMR, EPR, and Mossbauer spectroscopy. The phosphatase activity of the diferric systems, in addition to the partially reduced heterovalent [(FeFeII)-Fe-III(L-3)(OH)(OH2)(2)](3+) complex, has been investigated, and the complexes are shown to catalytically hydrolyze the activated phosphodiester substrate BDNPP (bis-dinitrophenylphosphate) as well as the corresponding phosphomonoester substrate DNPP (dinitrophenylphosphate). The results indicate that indeed the secondary interactions lead to an increase of the phosphatase activity and to active phosphomonoesterase catalysts. Interestingly, the heterovalent form of the HL3-based complex is more efficient than the diferric complex, and this is also discussed.