Modeling the Resting State of Oxalate Oxidase and Oxalate Decarboxylase Enzymes
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- 作者：Marciela Scarpellini ; Jessica Gä ; tjens ; Ola J. Martin ; Jeff W. Kampf ; Suzanne E. Sherman ; Vincent L. Pecoraro
- 刊名：Inorganic Chemistry
- 出版年：2008
- 出版时间：May 5, 2008
- 年：2008
- 卷：47
- 期：9
- 页码：3584 - 3593
- 全文大小：3353K
- 年卷期：v.47,no.9(May 5, 2008)
- ISSN：1520-510X
文摘
In view of the biological and commercial interest in models for Oxalate Decarboxylases (OxDC) and Oxalate Oxidases (OxOx), we have synthesized and characterized three new MnII complexes (1−3) employing N3O-donor amino-carboxylate ligands (TCMA, 1,4,7-triazacyclononane-N-acetic acid; KiPr2TCMA, potassium 1,4-diisopropyl-1,4,7-triazacyclononane-N-acetate; and KBPZG, potassium N,N-bis(3,5-dimethylpyrazolyl methyl)glycinate). These complexes were characterized by several techniques including X-ray crystallographic analysis, X-band electron paramagnetic resonance (EPR), electrospray ionization mass spectrometry (ESI-MS), and cyclic voltammetry. The crystal structures of 1 and 3 revealed that both form infinite polymeric chains of MnII complexes linked by the pendant carboxylate arms of the TCMA− and the BPZG− ligands in a syn-antipattern. Complex 2 crystallizes as a mononuclear MnII cation, six-coordinate in a distorted octahedral geometry. Although complexes 1 and 3 crystallize as polymeric chains, all compounds present the same N3O-donor set atoms around the metal center as observed in the crystallographically characterized OxDC and OxOx. Moreover, complex 2 also contains two water molecules coordinated to the Mn center as observed in the active site of OxDC and OxOx. ESI-MS spectrometry, combined with EPR, were useful techniques to establish that complexes 1−3 are present as mononuclear MnII species in solution. Finally, complexes 1−3 are able to model the resting state active sites, with special attention focused on complex 2 which provides the first exact first coordination sphere ligand structural model for the resting states of both OxDC and OxOx.