title: Modeling the resting state of oxalate oxidase and oxalate decarboxylase enzymes.
abstract: 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 Mn (II) complexes ( 1- 3) employing N3O-donor amino-carboxylate ligands (TCMA, 1,4,7-triazacyclononane- N-acetic acid; K (i) Pr 2TCMA, 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 Mn (II) complexes linked by the pendant carboxylate arms of the TCMA (-) and the BPZG (-) ligands in a syn-antipattern. Complex 2 crystallizes as a mononuclear Mn (II) 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 Mn (II) 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.
authors.affiliation: Willard H. Dow Laboratories, Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, MI 48109, USA.
authors.forename: Marciela
authors.initials: M
authors.lastname: Scarpellini
authors.forename: Jessica
authors.initials: J
authors.lastname: Gätjens
authors.forename: Ola J
authors.initials: OJ
authors.lastname: Martin
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Kampf
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Sherman
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Pecoraro
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology; D001665:Binding Sites; D002262:Carboxy-Lyases / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D006571:Heterocyclic Compounds / Q000737:chemistry; D001467:Hordeum / Q000201:enzymology; D008345:Manganese / Q000737:chemistry; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry; D010088:Oxidoreductases / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D020124:Thermotoga maritima / Q000201:enzymology
chemical_list: D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D008345:Manganese; C075712:1,4,7-triazacyclononane; D010088:Oxidoreductases; C020598:oxalate oxidase; D002262:Carboxy-Lyases; C021915:oxalate decarboxylase