Johnston Esther M, Dell'Acqua Simone, Ramos Susana, Pauleta Sofia R, Moura Isabel, Solomon Edward I
Department of Chemistry, Stanford University , Stanford, California 94305-5080, United States.
J Am Chem Soc. 2014 Jan 15;136(2):614-7. doi: 10.1021/ja411500p. Epub 2014 Jan 7.
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.
已发现N2OR的四核铜活性位点有两种结构形式，即4CuS Cu(Z)*形式和4Cu2S Cu(Z)形式。电子顺磁共振（EPR）、共振拉曼光谱和磁圆二色光谱（MCD）已被用于确定在不同还原剂条件下这些位点的氧化还原状态，结果表明Cu(Z)*位点可达到单空穴和完全还原的氧化还原状态，而Cu(Z)位点可达到双空穴和单空穴氧化还原状态。处于这些氧化还原状态的Cu(Z)和Cu(Z)*的N2OR单周转反应以及不同比例Cu(Z)和Cu(Z)*的稳态周转测定表明，只有完全还原的Cu(Z)*在与N2O的快速周转中具有催化活性。
