Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA.
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Angew Chem Int Ed Engl. 2023 May 8;62(20):e202215719. doi: 10.1002/anie.202215719. Epub 2023 Apr 4.
While native CO -reducing enzymes display remarkable catalytic efficiency and product selectivity, few artificial biocatalysts have been engineered to allow understanding how the native enzymes work. To address this issue, we report cobalt porphyrin substituted myoglobin (CoMb) as a homogeneous catalyst for photo-driven CO to CO conversion in water. The activity and product selectivity were optimized by varying pH and concentrations of the enzyme and the photosensitizer. Up to 2000 TON(CO) was attained at low enzyme concentrations with low product selectivity (15 %), while a product selectivity of 74 % was reached by increasing the enzyme loading but with a compromised TON(CO). The efficiency of CO generation and overall TON(CO) were further improved by introducing positively charged residues (Lys or Arg) near the active stie of CoMb, which demonstrates the value of tuning the enzyme secondary coordination sphere to enhance the CO -reducing performance of a protein-based photocatalytic system.
虽然天然的一氧化碳还原酶具有显著的催化效率和产物选择性，但很少有经过工程设计的人工生物催化剂能够让我们了解天然酶的工作原理。为了解决这个问题，我们报告了钴卟啉取代肌红蛋白（CoMb）作为一种均相催化剂，可在水中光驱动 CO 转化为 CO。通过改变酶和光敏剂的 pH 值和浓度来优化其活性和产物选择性。在低酶浓度下，可获得高达 2000 TON(CO)的产率和低产物选择性（15%），而通过增加酶负载量可获得 74%的产物选择性，但 TON(CO)会受到影响。通过在 CoMb 的活性位点附近引入正电荷残基（Lys 或 Arg），进一步提高了 CO 的生成效率和整体 TON(CO)，这表明调节酶的二级配位环境对于提高基于蛋白质的光催化体系的 CO 还原性能具有重要价值。
