Determination of the Active Form of the Tetranuclear Copper Sulfur Cluster in Nitrous Oxide Reductase

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• 作者：Esther M. Johnston ; Simone Dell’Acqua ; Susana Ramos ; Sofia R. Pauleta ; Isabel Moura ; Edward I. Solomon
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：January 15, 2014
• 年：2014
• 卷：136
• 期：2
• 页码：614-617
• 全文大小：230K
• ISSN：1520-5126

文摘

N₂OR has been found to have two structural forms of its tetranuclear copper active site, the 4CuS Cu_Z* form and the 4Cu2S Cu_Z form. EPR, resonance Raman, and MCD spectroscopies have been used to determine the redox states of these sites under different reductant conditions, showing that the Cu_Z* site accesses the 1-hole and fully reduced redox states, while the Cu_Z site accesses the 2-hole and 1-hole redox states. Single-turnover reactions of N₂OR for Cu_Z and Cu_Z* poised in these redox states and steady-state turnover assays with different proportions of Cu_Z and Cu_Z* show that only fully reduced Cu_Z* is catalytically competent in rapid turnover with N₂O.