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| == Function == | | == Function == |
| [https://www.uniprot.org/uniprot/A0A077JBW9_9SPHN A0A077JBW9_9SPHN] | | [https://www.uniprot.org/uniprot/A0A077JBW9_9SPHN A0A077JBW9_9SPHN] |
| <div style="background-color:#fffaf0;">
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| == Publication Abstract from PubMed ==
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| A novel phosphotriesterase was recently discovered and purified from Sphingobium sp. TCM1 (Sb-PTE) and shown to catalyze the hydrolysis of a broad spectrum of organophosphate esters with a catalytic efficiency that exceeds 106 M-1 s-1 for the hydrolysis of triphenyl phosphate. The enzyme was crystallized and the three-dimensional structure determined to a resolution of 2.1 A using single-wavelength anomalous diffraction (Protein Data Bank entry 5HRM ). The enzyme adopts a seven-bladed beta-propeller protein fold, and three disulfide bonds were identified between Cys-146 and Cys-242, Cys-411 and Cys-443, and Cys-542 and Cys-559. The active site of Sb-PTE contains a binuclear manganese center that is nearly identical to that of the structurally unrelated phosphotriesterase from Pseudomonas diminuta (Pd-PTE). The two metal ions in the active site are bridged to one another by Glu-201 and a water molecule. The alpha-metal ion is further coordinated to the protein by interactions with His-389, His-475, and Glu-407, whereas the beta-metal ion is further liganded to His-317 and His-258. Computational docking of mimics of the proposed pentavalent reaction intermediates for the hydrolysis of organophosphates was used to provide a model for the binding of chiral substrates in the active site of Sb-PTE. The most striking difference in the catalytic properties of Sb-PTE, relative to those of Pd-PTE, is the enhanced rate of hydrolysis of organophosphate esters with substantially weaker leaving groups. The structural basis for this difference in the catalytic properties between Sb-PTE and Pd-PTE, despite the nearly identical binuclear metal centers for the activation of the substrate and nucleophilic water molecule, is at present unclear.
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| Structure of a Novel Phosphotriesterase from Sphingobium sp. TCM1: A Familiar Binuclear Metal Center Embedded in a Seven-Bladed beta-Propeller Protein Fold.,Mabanglo MF, Xiang DF, Bigley AN, Raushel FM Biochemistry. 2016 Jul 8. PMID:27353520<ref>PMID:27353520</ref>
| | ==See Also== |
| | | *[[Phosphotriesterase 3D structures|Phosphotriesterase 3D structures]] |
| From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| </div>
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| <div class="pdbe-citations 5hrm" style="background-color:#fffaf0;"></div>
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| == References == | |
| <references/>
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| __TOC__ | | __TOC__ |
| </StructureSection> | | </StructureSection> |