1] Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands [2].
Nat Chem. 2013 Nov;5(11):945-51. doi: 10.1038/nchem.1752. Epub 2013 Sep 22.
In processive catalysis, a catalyst binds to a substrate and remains bound as it performs several consecutive reactions, as exemplified by DNA polymerases. Processivity is essential in nature and is often mediated by a clamp-like structure that physically tethers the catalyst to its (polymeric) template. In the case of the bacteriophage T4 replisome, a dedicated clamp protein acts as a processivity mediator by encircling DNA and subsequently recruiting its polymerase. Here we use this DNA-binding protein to construct a biohybrid catalyst. Conjugation of the clamp protein to a chemical catalyst with sequence-specific oxidation behaviour formed a catalytic clamp that can be loaded onto a DNA plasmid. The catalytic activity of the biohybrid catalyst was visualized using a procedure based on an atomic force microscopy method that detects and spatially locates oxidized sites in DNA. Varying the experimental conditions enabled switching between processive and distributive catalysis and influencing the sliding direction of this rotaxane-like catalyst.
在连续催化中，催化剂与底物结合，并在进行几个连续反应时保持结合，例如 DNA 聚合酶。连续催化在自然界中至关重要，通常由一种类似夹子的结构介导，该结构将催化剂物理地固定在其（聚合）模板上。在噬菌体 T4 复制体的情况下，专门的夹子蛋白通过环绕 DNA 并随后招募其聚合酶来充当连续催化的介质。在这里，我们使用这种 DNA 结合蛋白来构建生物杂交催化剂。将夹子蛋白与具有序列特异性氧化行为的化学催化剂连接形成催化夹子，该夹子可以加载到 DNA 质粒上。使用基于原子力显微镜方法的程序可视化生物杂交催化剂的催化活性，该程序可检测和定位 DNA 中的氧化位点。改变实验条件可以在连续催化和分布催化之间切换，并影响这种轮烷状催化剂的滑动方向。
