Department of Biochemistry, 1462 Boyce Hall, University of California, Riverside, California 92521, USA.
J Am Chem Soc. 2011 Aug 24;133(33):12934-6. doi: 10.1021/ja205073j. Epub 2011 Aug 3.
Carbon monoxide dehydrogenase from Oligotropha carboxidovorans catalyzes the aerobic oxidation of carbon monoxide to carbon dioxide, providing the organism both a carbon source and energy for growth. The active site of the native enzyme is a unique binuclear molybdenum- and copper-containing center. Here we show that silver can be substituted for copper in the active site to yield a functional enzyme. The characteristic hyperfine coupling of the I = ½ nucleus of Ag is evident in the EPR signal of the binuclear active site observed upon reduction with CO, indicating both the incorporation of silver into the active site and, remarkably, retention of the catalytic activity. The silver-substituted enzyme is reduced by CO with an observed limiting rate constant of 8.1 s(-1), which can be compared with the value of 51 s(-1) for the wild-type enzyme. Steady-state kinetics for the Ag-substituted enzyme yielded k(cat) = 8.2 s(-1) and K(m) = 2.95 μM at pH 7.2.
来源于寡养单胞菌的一氧化碳脱氢酶能够催化一氧化碳的有氧氧化为二氧化碳，为该生物体提供碳源和生长所需的能量。天然酶的活性部位是一个独特的双核含钼和铜的中心。在这里，我们发现银可以取代活性部位的铜来生成有功能的酶。在与 CO 还原时观察到的双核活性部位的 EPR 信号中，Ag 的 I = ½ 核的特征超精细耦合很明显，这表明银被掺入到活性部位，而且令人惊讶的是，保持了催化活性。银取代的酶与 CO 还原的观察到的限速常数为 8.1 s(-1)，这可以与野生型酶的 51 s(-1)值进行比较。银取代酶的稳态动力学在 pH 7.2 时得到 k(cat) = 8.2 s(-1)和 K(m) = 2.95 μM。
